Measurement of the semileptonic tt-bar gamma production cross section in pp collisions at sqrt(s) = 8 TeV

TL;DR

This paper reports a measurement of the cross section for top quark-antiquark pairs produced with a photon in proton-proton collisions at 8 TeV, using CMS data, and finds results consistent with theoretical predictions.

Contribution

First measurement of tt-bar plus photon production cross section in proton-proton collisions at 8 TeV with CMS data.

Findings

Fiducial cross section measured as 127 +/- 27 fb.

Results agree with theoretical predictions.

Analysis performed in semileptonic decay channel.

Abstract

A measurement of the cross section for top quark-antiquark (tt-bar) pairs produced in association with a photon in proton-proton collisions at sqrt(s) = 8 TeV is presented. The analysis uses data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.7 inverse femtobarns. The signal is defined as the production of a tt-bar pair in association with a photon having a transverse energy larger than 25 GeV and an absolute pseudorapidity smaller than 1.44. The measurement is performed in the fiducial phase space corresponding to the semileptonic decay chain of the tt-bar pair, and the cross section is measured relative to the inclusive tt-bar pair production cross section. The fiducial cross section for associated tt-bar pair and photon production is found to be 127 +/- 27 (stat + syst) fb per semileptonic final state. The measured value is in agreement with the theoretical prediction.

Figures

Equations

$${\chi }^2({\mathrm{SF}}_{\text{ttbar}\text{+}\gamma },{\mathrm{SF}}_{\text{cmsSymbolFace}V\text{+}\gamma },{\mathrm{SF}}_{\text{jet}\to \gamma })=\frac{({\pi }_{\text{Pe}\gamma }^{\text{data}}-{\pi }_{\text{Pe}\gamma }^{\text{MC}}{)}^2}{{\sigma }_{{\pi }_{\text{Pe}\gamma }}^2}+\frac{({\pi }_{\text{ttbar}}^{\text{data}}-{\pi }_{\text{ttbar}}^{\text{MC}}{)}^2}{{\sigma }_{{\pi }_{\text{ttbar}}}^2}+\frac{(N^{\text{data}}-N^{\text{MC}}{)}^2}{{\sigma }_N^2},$$

$${\sigma }_{\text{ttbar}\text{+}\gamma }^{\text{fid.}}=\frac{N_{\text{ttbar}\text{+}\gamma }}{{ϵ}^{\text{ttbar}\text{+}\gamma }L},{\sigma }_{\text{ttbar}\text{+}\gamma }=\frac{N_{\text{ttbar}\text{+}\gamma }}{A^{\text{ttbar}\text{+}\gamma }{ϵ}^{\text{ttbar}\text{+}\gamma }L}=\frac{{\sigma }_{\text{ttbar}\text{+}\gamma }^{\text{fid.}}}{A^{\text{ttbar}\text{+}\gamma }},$$

$$R=\frac{{\sigma }_{\text{ttbar}\text{+}\gamma }^{\text{fid}}}{{\sigma }_{\text{ttbar}}}=\frac{N_{\text{ttbar}\text{+}\gamma }}{{ϵ}^{\text{ttbar}\text{+}\gamma }}\frac{{ϵ}_{\text{top}}^{\text{ttbar}}{A}_{\text{top}}^{\text{ttbar}}}{N_{\text{ttbar}}},$$

Full text

0.1 Introduction

As the heaviest elementary particle in the standard model (SM), the top quark has the potential to provide insights into physics beyond the SM (BSM). Many BSM models introduce changes within the top quark sector [1, 2], which can be constrained by precise measurements of the cross sections and properties of top quark production channels  [3]. By measuring the associated production cross section of a top quark-antiquark pair and a photon ($\ttbar\text{+}\gamma$), the coupling of the top quark and the photon is probed [4, 5]. Any deviation of the measured cross section value from the SM prediction would be an indication of BSM physics, such as the production of an exotic quark with electric charge of $-$4/3, or a top quark with an anomalous electric dipole moment [6, 7].

As the top quark predominantly decays to a W boson and a b quark, the $\ttbar\text{+}\gamma$ production can be identified by the presence of a photon candidate and the decay products of a pair of top quarks, namely two jets from the hadronization of two b quarks, and the decay products of a pair of W bosons. In this analysis, events are selected in which one W boson decays leptonically, resulting in an electron or muon and a corresponding neutrino $\nu$, and the other W boson decays hadronically. Examples of two Feynman diagrams for the $\ttbar\text{+}\gamma$ process in the semileptonic final states are shown in Fig. 1. In the signal definition we include possible contributions from $\PW\to\tau\nu_{\tau}$, where the $\tau$ lepton decays further into an electron or a muon. The presence of a charged lepton from the W boson decay significantly improves the power to reject dominant backgrounds from multijet processes and allows for efficient triggering of signal events using single-lepton triggers.

Measurements of the production cross section of $\ttbar\text{+}\gamma$ have been performed by the CDF Collaboration at the Tevatron using $\Pp\PAp$ collisions at $\sqrt{s}=1.96\TeV$ [8], and by the ATLAS Collaboration at the LHC using $\Pp\Pp$ collisions at $\sqrt{s}=7\TeV$ [9] and $\sqrt{s}=8\TeV$ [10]. These results are in agreement with the SM predictions within uncertainties [11].

In this paper, the measurement of the $\ttbar\text{+}\gamma$ production cross section in $\Pp\Pp$ collisions at $\sqrt{s}=8\TeV$ is presented. The analysis is based on a data sample corresponding to an integrated luminosity of $19.7\fbinv$, recorded with the CMS detector in 2012. The measurement of the $\ttbar\text{+}\gamma$ production cross section in the semileptonic decay channel is performed relative to the \ttbarproduction cross section. The $\ttbar\text{+}\gamma$ cross section is measured in a fiducial kinematic region defined by the presence of exactly one charged lepton and corresponding neutrino, at least three jets, and a photon within the selection requirements.

0.2 The CMS detector

The central feature of the CMS apparatus is a superconducting solenoid of 6\unitm internal diameter, providing a magnetic field of 3.8\unitT. Within the solenoid volume are a silicon pixel and strip tracker, a lead tungstate crystal electromagnetic calorimeter (ECAL), and a brass and scintillator hadron calorimeter, each composed of a barrel and two endcap sections. Forward calorimeters extend the pseudorapidity $\eta$ coverage provided by the barrel and endcap detectors. Muons are detected in gas-ionization chambers embedded in the steel flux-return yoke outside the solenoid. In the barrel section of the ECAL, an energy resolution of about 1% is achieved for unconverted or late-converting photons in the tens of\GeVenergy range, relevant to this analysis. The remaining barrel photons have a resolution of about 1.3% up to $\abs{\eta}=1$, rising to about 2.5% at $\abs{\eta}=1.4$. In the endcaps, the resolution of unconverted or late-converting photons is about 2.5%, while the remaining endcap photons have a resolution between 3 and 4% [12]. A more detailed description of the CMS detector, together with a definition of the coordinate system used and the relevant kinematic variables, can be found in Ref. [13].

0.3 Signal and background modeling

The signal process produces events in which a pair of top quarks is produced in association with a photon. This process includes photons radiated from the top quarks as well as from initial state partons or the decay products of the top quarks. The simulation of the $\ttbar\text{+}\gamma$ signal process is performed in the region with photons having transverse momentum (\pt) of at least 13\GeVand $\abs{\eta}<3.0$, as well as having a separation from all other generated particles of at least $\Delta R>0.3$, where $\Delta R=\sqrt{\smash[b]{(\Delta\phi)^{2}+(\Delta\eta)^{2}}}$, and $\Delta\phi$ and $\Delta\eta$ are the differences in the azimuthal angle (in radians) and pseudorapidity, respectively, between the generated particles and the photon. For the purpose of this analysis, nonprompt photons originating from jets are not included in the definition of the $\ttbar\text{+}\gamma$ signal process.

The $\ttbar\text{+}\gamma$ signal process is simulated at leading order (LO) using the \MADGRAPHv5.1.3.30 generator [14]. The dominant backgrounds, $\ttbar$, $\cmsSymbolFace{V}\text{+jets}$, and $\cmsSymbolFace{V}\text{+}\gamma$ (where $\cmsSymbolFace{V}=\PW$, $\cPZ$), are also simulated using the \MADGRAPHgenerator. Single top quark production is simulated at next-to-leading order (NLO) using the \POWHEGv1.0 r1380 event generator [15, 16, 17, 18]. In order to avoid any overlap between the simulation of the $\ttbar\text{+}\gamma$ signal and the inclusive \ttbarprocess, events that fall under the $\ttbar\text{+}\gamma$ signal definition are removed from \ttbarsimulation. Overlap between $\cmsSymbolFace{V}\text{+}\gamma$ and $\cmsSymbolFace{V}\text{+jets}$ simulation is also taken into account by removing events from $\cmsSymbolFace{V}\text{+jets}$ samples, which are accounted for in the $\cmsSymbolFace{V}\text{+}\gamma$ simulation. Approximately 1% of events from \ttbarsimulation and approximately 3% of $\cmsSymbolFace{V}\text{+jets}$ events are removed through this procedure.

The parton showering and hadronization for all simulated samples are handled by \PYTHIAv6.426 [19], with the decays of $\tau$ leptons modeled with \TAUOLAv27.121.5 [20]. The CTEQ6L1 and CTEQ6M [21] parton distribution functions (PDFs) are used for samples simulated at LO and NLO, respectively. A top quark mass $m_{\cPqt}=172.5\GeV$ is used in the simulation. The response of the full CMS detector is simulated with \GEANTfourv9.4 [22, 23], followed by a detailed trigger simulation and event reconstruction. The \PYTHIAevent generator is used to simulate the presence of additional $\Pp\Pp$ interactions in the same and nearby bunch crossings (“pileup”). Simulated events are reweighted to correct for differences between the number of pileup interactions observed from data and the number produced in the simulation.

A cross section of $244.9\pm 1.4\stat^{+6.3}_{-5.5}\syst\pm 6.4\lum$\unitpb is used to normalize the \ttbarbackground [24]. The next-to-next-to-leading-order (NNLO) SM prediction is calculated with fewz v3.1 [25, 26] for the $\cmsSymbolFace{V}\text{+jets}$ backgrounds. The $\PW\text{+}\gamma$ and $\Z\text{+}\gamma$ simulations are normalized to their NLO predictions, calculated with \MCFMv6.6 [27]. Values of 553.9\unitpb for the leptonic decay of the W+gamma process and 159.1\unitpb for the leptonic decay of the Z+gamma process are used. The single top quark samples are normalized to their approximate NNLO predictions [28, 29].

0.4 Event reconstruction and selection

The final state of the signal process in the semileptonic decay channel consists of a high-\ptcharged lepton, momentum imbalance due to the presence of a neutrino, jets originating from both the $\cPqb$ quarks and from the decay of a W boson, and an energetic photon. Events with either a high-\ptelectron or muon are initially selected through a single-lepton trigger. Events in the $\Pe\text{+jets}$ final state must pass a trigger requiring an electron with $\pt>27$\GeVwithin $\abs{\eta}<2.5$ and a relative isolation of less than 0.2, where the relative isolation is defined as the sum of the \ptof all particles, excluding the lepton, within a cone around the lepton of $\Delta R=0.3$, divided by the \ptof the lepton. The $\Pgm\text{+jets}$ final state requires a single-muon trigger selecting a muon with $\pt>24$\GeVwithin $\abs{\eta}<2.1$ and relative isolation less than 0.3 within $\Delta R=0.4$. Events are additionally required to have a well reconstructed primary vertex [30], chosen as the one having the largest sum $\pt^{2}$ of the tracks associated with it.

The particle-flow (PF) algorithm is used to reconstruct individual particles in the event [31]. The PF objects include electrons, muons, charged and neutral hadrons, photons, and an imbalance of the transverse momentum. The following describes the selection of reconstructed objects that are used in the analysis.

Electrons are reconstructed from energy deposits in the ECAL matched to a track from the tracker [32]. Electrons are required to have $\pt>35$\GeVand $\abs{\eta}<2.5$. excluding the transition region between the barrel and endcap of the ECAL, $1.44<\abs{\eta}<1.57$. Electrons from the decay of the top quark are expected to be isolated from other activity in the detector and thus have a requirement that the relative isolation must be less than 0.1. Selected electrons are required to be originating from the primary vertex, and are rejected if identified as likely having originated from a converted photon. Additionally, a multivariate-based identification is applied to reduce the contribution from nonprompt or misidentified electrons. Electrons that fail the above criteria, but pass looser identification requirements ($\pt>20\GeV$, $\abs{\eta}<2.5$, and a relative isolation less than 0.2 within a cone of size $\Delta R=0.3$) are considered to be “loose” electrons. The presence of loose electrons can then be used to reject events from the dilepton final state.

Muons are reconstructed based on measurements from both the tracker and muon systems. Selected muons are required to have $\pt>26\GeV$ and $\abs{\eta}<2.1$. A requirement on relative isolation less than 0.2 within a cone of $\Delta R=0.4$ is applied. Loose muons are defined as failing the tight requirements but passing a selection in which the \ptthreshold is lowered to 10\GeVand $\abs{\eta}<2.5$, with the same requirement on the relative isolation as the tight selection.

Jets are reconstructed from PF candidates clustered using the anti-$\kt$ algorithm with a distance parameter of 0.5 [33, 34]. Jets must have $\pt>30\GeV$ and $\abs{\eta}<2.4$. To remove the contribution to the jet energy from pileup interaction, charged hadrons candidates associated with other vertices are not included in the clustering, and an offset correction to the energy is applied for the contribution of neutral hadrons that would fall within the jet area. Additionally, corrections for the jet energy scale and resolution are applied in simulation, to account for imperfect measurements of the energy of the jet in the detector [35].

Jets are identified as originating from the hadronization of b quarks (b tagged) using the combined secondary vertex algorithm, which combines secondary vertex and track-based lifetime information to provide a discriminant between jets originating from the fragmentation of b quarks and light quarks or gluons. The b tagging algorithm has an efficiency of approximately 70%, while having a probability of incorrectly b tagging a light jet of only 1.4% [36, 37].

Photons are reconstructed as energy deposits in the ECAL that are not matched to track seeds in the pixel detector [12]. The photon is required to have $\pt>25\GeV$ and $\abs{\eta}<1.44$ (ECAL barrel). A selection based on the shape of the shower caused by the photon in the ECAL is applied using the $\sigma_{\eta\eta}$ variable, which measures the lateral spread of energy in the $\eta$ space [12]. Selected photons are required to have $\sigma_{\eta\eta}<0.012$. This is used to distinguish genuine photons from hadronic activity that can be reconstructed as a photon, as the latter will tend to produce a wider energy spread in $\eta$, leading to a larger value of $\sigma_{\eta\eta}$. As photons can convert into a pair of electrons before reaching the calorimeter, photon showers along $\phi$ can be larger compared to that of an electron. Thus, the isolation is defined differently for photons than it was for leptons, in order to account for a possible energy leakage along $\phi$. A characteristic photon energy deposition profile, or “footprint”, is used to restrict the area used to calculate isolation of the photon candidate. The charged-hadron isolation variable for photons is defined as the sum of the \ptof all charged hadrons spatially separated from the photon candidate by $\Delta R=0.3$, but not falling within the photon footprint. The charged-hadron isolation is required not to exceed 5\GeVfor selected photons, to help distinguish prompt photons from nonprompt photons produced from hadronic activity.

The missing transverse momentum (\ptmiss) is defined as the magnitude of the vector sum of the momenta of all reconstructed PF candidates in the event, projected on the plane perpendicular to the beams.

The final event selection is divided in two steps: a preselection designed to select events with the same topology as top quark pairs (referred to as the “top quark selection”), and a “photon selection”. The top quark selection requires:

• •

exactly one lepton passing the selection requirements (either an electron or muon);

• •

no other lepton candidates passing loose selection criteria;

• •

at least 3 jets, with at least one of these jets passing the b tagging requirement; and

• •

$\ptmiss>20\GeV$.

The photon selection requires that events pass the top quark selection and additionally have at least one photon passing the identification and isolation requirements described above.

0.5 Analysis strategy

After the photon selection is applied, over half of the events in simulation originate from background processes, and not $\ttbar\text{+}\gamma$ production. The two largest backgrounds are from \ttbarevents that have a nonprompt photon coming from jets in the event and from $\cmsSymbolFace{V}\text{+}\gamma$ events. There is not a single variable that can sufficiently discriminate both of these backgrounds from the $\ttbar\text{+}\gamma$ signal. The $\cmsSymbolFace{V}\text{+}\gamma$ background can be differentiated from $\ttbar\text{+}\gamma$ events by attempting to reconstruct a top quark in the event. However, \ttbarevents are very similar to the signal in this respect. Alternatively, the nonprompt photon from the \ttbarbackground will tend to be less isolated than the photons from the $\ttbar\text{+}\gamma$ signal, but the photon isolation variable does not have discrimination power to distinguish the $\cmsSymbolFace{V}\text{+}\gamma$ background from $\ttbar\text{+}\gamma$ events. In order to be able to distinguish both \ttbarand $\cmsSymbolFace{V}\text{+}\gamma$ background events, both of these methods are used and the results are combined to measure the $\ttbar\text{+}\gamma$ yield observed in data.

The fraction of events passing the photon selection containing top quark pairs, referred to as the “top quark purity”, can be measured by reconstructing the hadronically decaying top quark in the event. The $M_{3}$ variable, defined as the invariant mass of the three-jet combination that gives the highest vector sum of individual jet transverse momenta, is used for this purpose. Section 0.7 describes the fit to the distribution of the $M_{3}$ variable, used to distinguish top quark pair events from other backgrounds.

Section 0.8 describes the measurement of the “photon purity”, defined as the fraction of reconstructed photons in the selection region, which come from genuine, isolated photons as opposed to misidentified photons originating from jets. A fit to the photon isolation is used to measure this quantity, which can discriminate between the genuine photons expected from signal and the nonprompt photons from the \ttbarbackground.

The fits for extracting the top quark and photon purity are performed sequentially, and then the values are used in a likelihood function, from which a fit is performed to extract the number of events that originate from the $\ttbar\text{+}\gamma$ signal process. The likelihood fit and extraction of the number of $\ttbar\text{+}\gamma$ events are described in Section 0.9.

0.6 Multijet and Z+jets background estimation

The quantum chromodynamics (QCD) multijet process is not adequately modeled by simulation, so a data-based approach is applied to measure the shape and normalization of this background component. The shape of the QCD multijet background is taken from a sideband region in data. The sideband region is defined by inverting the lepton relative isolation requirement, selecting leptons with a relative isolation greater than 0.25. Additionally, in the $\Pe\text{+jets}$ final state the requirement on the multivariate-based electron identification is inverted, selecting electrons that would typically be identified as misidentified or nonprompt. This control region is dominated by QCD multijet events, with only minor contributions from other processes such as \ttbarand $\PW\text{+jets}$. The small contribution in the control region from other processes is subtracted using simulation to provide shapes of the variable distributions used in the analysis.

The normalization of the QCD multijet background is measured through a binned maximum-likelihood fit to the \ptmissdistribution after the standard top quark selection is applied. The distribution of \ptmissis softer in the QCD multijet background than the other processes considered, and thus provides some discriminating power for this background. For the purposes of the fit, the selection requirement on \ptmissis removed, in order to improve the discriminating power of the fit by bringing in more multijet events into the fit region. Two distributions are used in the fit, one for the multijet background and one for the contribution from all other processes. The distribution for the multijet background is taken from the shape found in the sideband control region, while the second distribution is taken from the sum of all simulated events (which does not include the QCD background component). The fit is performed separately in the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final states, and the results are used to scale the QCD multijet background distributions later in the analysis.

The normalization and modeling of the $\Z\text{+jets}$ background distribution is taken from simulation, but the normalization is corrected by applying a scale factor derived from a fit to data. In order to check the normalization, the selection is modified, selecting same-flavor dilepton events, while keeping all other top quark selection requirements in place. A binned maximum-likelihood fit is performed to the dilepton invariant mass for events passing this modified selection. The fit is performed using two normalized distributions (templates) from simulation, a $\Z\text{+jets}$ template and a background template, which predominantly contains \ttbarevents. Scale factors for the normalization of the $\Z\text{+jets}$ background are derived from the fit and applied to the simulation.

0.7 Estimate of top quark pair production

The number of events containing top quark pairs, both after the top quark selection and for events passing the photon selection, are extracted through a binned maximum-likelihood fit to the distribution of the $M_{3}$ variable. In events with semileptonic decays of the top quark pair, the $M_{3}$ variable provides a simple reconstruction of the hadronically decaying top quark, and has a distribution peaking at the mass of the top quark. Other processes have a wider $M_{3}$ distribution.

Two separate fits are performed to the $M_{3}$ distribution. The first fit is performed after the top quark selection, to extract the total number of \ttbarevents passing the selection, $N_{\ttbar}$. The second fit is performed for events passing the photon selection in order to measure the top quark purity.

0.7.1 Measurement of the \ttbaryield

The fit to the $M_{3}$ distribution for events passing the top quark selection is used to extract the total number of top quark pairs, used for measuring the \ttbarcomponent of the cross section ratio. The fit uses three templates: associated to top quark events (taken from \ttbarand $\ttbar\text{+}\gamma$ simulation), $\PW\text{+jets}$, and other background processes. The template for the other background processes is a combination of the data-based QCD multijet background and all other simulated samples. In the fit, the normalizations of the top quark and $\PW\text{+jets}$ templates are allowed to float, while the normalizations of the other backgrounds templates are kept fixed. The QCD multijet background is normalized to the fit to the \ptmissdistribution, while other simulated samples are scaled to their theoretical cross sections. From the fit, $162168\pm 1565\ \text{(stat)}$ and $219128\pm 1869\ \text{(stat)}$ \ttbarevents are observed in the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final states, respectively, consistent with the expected total number of \ttbarevents. The fit results are used to scale the normalization of the \ttbarand $\PW\text{+jets}$ contributions in the rest of the analysis.

0.7.2 Measurement of the top quark purity

After the photon selection, a fit to the $M_{3}$ distribution is used to measure the top quark purity. The fit uses three templates: associated to top quark events, $\PW\text{+}\gamma$ events, and the sum of all other processes. In the fit, the normalizations of the top quark and $\PW\text{+}\gamma$ templates are varied, while the templates of all other processes remain fixed. The top quark template contains simulated events for both $\ttbar\text{+}\gamma$ and \ttbarsamples. Figure 2 shows the normalized $M_{3}$ distributions for $\ttbar\text{+}\gamma$, \ttbar, $\PW\text{+}\gamma$, and other background processes. The backgrounds from non-top quark processes have a wider distribution in this variable, while the $\ttbar\text{+}\gamma$ and \ttbarprocesses peak near the top quark mass with a tail caused by events with an incorrect assignment of the jets. The relative contributions of the $\ttbar\text{+}\gamma$ and \ttbarsamples to the top quark template are computed from the expected yields from simulation, though this does not change the shape of the top quark template as the two distributions are compatible. After the photon selection is applied, the distribution of the $M_{3}$ variable in many of the background processes begins to suffer from fluctuations caused by the limited number of simulated events. Because the photon selection does not change the shape of the $M_{3}$ distribution, the problem is solved by taking the shapes for the non-\ttbarprocesses from the events after the top quark selection, while retaining the normalization of the samples observed after the photon selection is applied.

Figure 3 shows the distribution of the $M_{3}$ variable in data and simulation, scaled to the result of the fit. From the fit result, the top quark purity is measured to be $0.70\pm 0.08\stat$ and $0.68\pm 0.06\stat$ in the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ channels, respectively. These are consistent with the expected values from simulation of $0.70\pm 0.03\stat$ in the $\Pe\text{+jets}$ final state and $0.72\pm 0.02\stat$ in the $\Pgm\text{+jets}$ final state, where the uncertainties are due to the limited number of simulated events.

0.8 Photon purity measurement

Events are sorted into one of three categories based on the origin of their reconstructed photons. Genuine photons are those which are promptly produced, originating from nonhadronic sources. Misidentified photons can come from misreconstructed electrons, for which the track from the electron is not correctly reconstructed or properly matched to the energy cluster in the calorimeter, causing the electron to be reconstructed as a photon. Quark or gluon fragmentation and hadronization processes can be misidentified as photons or yield genuine photons, which for both cases are expected to be nonisolated, in contrast with promptly produced photons. The $\ttbar\text{+}\gamma$ signal events predominantly fall within the first category while the latter two categories are mostly composed of background events.

Simulated events can be placed in one of these three categories based on matching between the reconstructed and generated photons. Matching is performed based on the difference between the reconstructed photon and the generated particles in both \ptand the $\eta$-$\phi$ phase space. If a reconstructed photon is matched to a generated photon from a nonhadronic source, it is classified in the first category. Reconstructed photons that are not matched to a generated photon but instead are matched to a generated electron are classified as misidentified electrons, and placed in the second category. All other events, which are not matched to either a generated photon or electron, are considered to be nonprompt photons originating from hadronic activity and placed in the third category.

Photons in the last category, which are produced from hadronic activity, are typically less isolated than genuine photons or misidentified electrons. This difference in the isolation distribution is used to measure the photon purity, defined as the fraction of events with a photon originating from an isolated source (including both genuine photons and misidentified electrons). A binned maximum-likelihood fit to the distribution of the charged-hadron isolation is used to measure the photon purity.

Templates for the shape of the charged-hadron isolation for isolated photons (coming from either genuine photons or misidentified electrons) and nonprompt (nonisolated) photons are taken from data. The shape of the charged-hadron isolation for the isolated photon template is obtained using the random cone isolation method [38]. In this method, the sum of the transverse energy of PF charged-hadron candidates is measured within a cone of size $\Delta R=0.3$ at the same $\eta$ value as the reconstructed photon, but in a random $\phi$ direction. Contributions to the isolation sum from charged hadrons coming from pileup interactions are subtracted from the energy in the cone. This gives an estimate of the isolation of a completely isolated particle. The shape of the charged-hadron isolation for nonprompt photon events is taken from a sideband region. The charged-hadron isolation of events with a photon having $\sigma_{\eta\eta}$ between 0.012 and 0.016 is used to construct the template for nonisolated photons. These events typically have nonprompt, hadronically produced photons. Comparisons of the distributions of the charged-hadron isolation templates for isolated and nonprompt photons extracted from the data-based method and the templates taken from simulation using the generated particle matching are shown in Fig. 4.

In order to reduce the statistical fluctuations in the background template, the selection requirement of the photon charged-hadron isolation being less than 5\GeVis relaxed during the fit. Instead, the fit is performed in the range of charged-hadron isolation less than 20\GeV, with all other photon selection requirements still in place. The distribution suffers from lower statistical precision at higher values of the isolation, so the distribution is rebinned with larger bins for higher isolation values and finer binning for lower values where the statistical precision is better. Figure 5 shows the result of the fit of the photon charged-hadron isolation in a combination of the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final state. The photon purity is measured based on the fraction of events coming from isolated sources after the charged-hadron isolation requirement is put back in place. The photon purity is measured to be $0.57\pm 0.06\stat$ and $0.53\pm 0.06\stat$ in the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final states, respectively. The expected value for the photon purity in simulation, assuming the SM prediction for $\ttbar\text{+}\gamma$ production, is $0.58\pm 0.03$ in the $\Pe\text{+jets}$ final state and $0.57\pm 0.02$ in the $\Pgm\text{+jets}$ final state.

In order to correct the rate of misidentified electrons in simulation, the $\cPZ\to\Pep\Pem$ process is used to measure events in which one of the electrons from the $\cPZ$ boson decay is misidentified as a photon. If the photon originates from a misidentified electron from the $\cPZ$ boson decay, the invariant mass of the combination of the electron and photon in the event will be near the $\cPZ$ boson mass.

Under the nominal event selection described previously, the contribution from $\cPZ$ boson production is highly suppressed and does not provide a large enough sample of events to measure the electron misidentification rate accurately. In order to improve the statistical precision, the event selection is modified by relaxing the requirement of having a b-tagged jet in the event, while keeping all other requirements the same. This enhances the contribution of $\cPZ\to\Pep\Pem$ events. All steps for the multijet estimation and $M_{3}$ fit are repeated for this new selection.

The removal of the b tagging requirement makes the $\cPZ$ boson mass peak much more pronounced in the $\Pe\gamma$ invariant mass distribution. This allows a template fit to be performed, in order to estimate how well the misidentification of an electron as a photon is modeled in simulation. The fit to the $\Pe\gamma$ invariant mass is performed using two templates, both derived from simulation. The first template consists of events with $\cPZ$ bosons in which the reconstructed photon is matched to one of the electrons from the $\cPZ$ boson decay at the generator level. The second template consists of all other simulated samples not included in the previous template and the data-based multijet sample. The result of the fit is shown in Fig. 6. A scale factor of $1.46\pm 0.20\stat$ is found for simulated events with a misidentified electron. This scale factor is applied to all simulated events in which the photon is identified as originating from a misidentified electron.

0.9 The $\ttbar+\gamma$ yield measurement

As previously mentioned, reconstructed photons originate from either a genuine photon, a misidentified electron, or a jet that produces a nonprompt photon. Different processes contribute to each of these three categories in different ways. For example, the $\ttbar\text{+}\gamma$ and $\cmsSymbolFace{V}\text{+}\gamma$ processes predominantly produce genuine photons, while the \ttbarand $\cmsSymbolFace{V}\text{+jets}$ processes contribute to the nonprompt-photon or misidentified-electrons categories. The breakdown of the number of events in the three reconstructed photon categories from each of the different simulated processes as well as the total number of expected and observed events are shown in Tables 0.9 and 0.9 for the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final states, respectively.

The modeling of misidentified electrons has been corrected using the scale factor described in Section 0.8, but the modeling of nonprompt photons from jets remains uncorrected. The normalization of the $\ttbar\text{+jets}$, $\PW\text{+jets}$, $\Z\text{+jets}$, and QCD samples have been cross-checked and corrected as described previously in Sections 0.6 and 0.7. The contribution from single top quark processes is expected to be small and accurately modeled, and is left normalized to the theoretical cross sections. This leaves three major contributing sources, which have so far not been constrained and for which scale factors still need to be measured: $\ttbar\text{+}\gamma$, $\cmsSymbolFace{V}\text{+}\gamma$, and photons originating from jets.

The three remaining scale factors, the scale factor on $\ttbar\text{+}\gamma$ simulation ($\mathrm{SF}_{\ttbar\text{+}\gamma}$), on $\cmsSymbolFace{V}\text{+}\gamma$ simulation ($\mathrm{SF}_{\cmsSymbolFace{V}\text{+}\gamma}$), and on simulation of photons originating from jets ($\mathrm{SF}_{\text{jet}\to\gamma}$), are derived by defining a likelihood function based on the three previously measured quantities: the photon purity, $\pi_{\Pe\gamma}^{\text{data}}$; top quark purity, $\pi_{\ttbar}^{\text{data}}$; and the number of events in data after the photon selection, $N^{\text{data}}$. The likelihood function is defined as $\mathcal{L}(\mathrm{SF}_{\ttbar\text{+}\gamma},\mathrm{SF}_{\cmsSymbolFace{V}\text{+}\gamma},\mathrm{SF}_{\text{jet}\to\gamma})=\re^{-\chi^{2}/2}$ where $\chi^{2}$ is the sum of three terms:

[TABLE]

where $\pi_{\Pe\gamma}^{\text{MC}},\pi_{\ttbar}^{\text{MC}}$, and $N^{\text{MC}}$ are the photon purity, top quark purity, and the number of events expected from simulation, and $\sigma_{\pi_{\Pe\gamma}}$ $\sigma_{\pi_{\ttbar}}$, and $\sigma_{N}$ are the statistical uncertainties in the measured quantities. The value of the photon purity from simulation is taken to be the fraction of events in which the reconstructed photon originates from either a genuine photon or a misidentified electron. Similarly, the top quark purity in simulation is found as the fraction of the total simulated events coming from either the \ttbaror $\ttbar\text{+}\gamma$ processes. Because these three values depend on the relative contribution of events from the different processes, they are functions of the three scale factors, $\mathrm{SF}_{\ttbar\text{+}\gamma}$, $\mathrm{SF}_{\cmsSymbolFace{V}\text{+}\gamma}$, and $\mathrm{SF}_{\text{jet}\to\gamma}$. For example, the photon purity would be increased for larger values of $\mathrm{SF}_{\ttbar\text{+}\gamma}$ or $\mathrm{SF}_{\cmsSymbolFace{V}\text{+}\gamma}$ whereas $\mathrm{SF}_{\text{jet}\to\gamma}$ would increase the number of nonprompt photons and have the inverse effect on the photon purity. Similarly the top quark purity would be increased for larger values of $\mathrm{SF}_{\ttbar\text{+}\gamma}$ or $\mathrm{SF}_{\text{jet}\to\gamma}$ (since \ttbaris the largest contributor of nonprompt photons), whereas $\mathrm{SF}_{\cmsSymbolFace{V}\text{+}\gamma}$ has the inverse effect. The likelihood fit is performed by scanning over the possible combinations of the three scale factors to find the one that results in values of $\pi_{\Pe\gamma}^{\text{MC}},\pi_{\ttbar}^{\text{MC}},$ and $N^{\text{MC}}$, which most closely match the values observed in data, and thus returns the maximum likelihood value.

The likelihood fit is performed in the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final states individually, as well as in a combination of the two channels. The combination is performed by maximizing the product of the likelihood functions from the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final states.

The scale factors obtained in the likelihood fit are applied to the simulation to extract the number of $\ttbar\text{+}\gamma$ events observed, $N_{\ttbar\text{+}\gamma}$. All $\ttbar\text{+}\gamma$ events are scaled by $\mathrm{SF}_{\ttbar\text{+}\gamma}$, and those which fall within the nonprompt-photon category are additionally scaled by $\mathrm{SF}_{\text{jet}\to\gamma}$. Applying the results of the fit in a combination of the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final states, $780\pm 119\stat$ $\ttbar\text{+}\gamma$ events are observed, $338\pm 53\stat$ events and $442\pm 69\stat$ events in the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final states, respectively. The uncertainty comes predominantly from the statistical uncertainty in the results of the likelihood fit.

0.10 Calculation of the cross section ratio

The fiducial $\ttbar\text{+}\gamma$ cross section ($\sigma^{\text{fid.}}_{\ttbar\text{+}\gamma}$) and the inclusive $\ttbar\text{+}\gamma$ cross section ($\sigma_{\ttbar\text{+}\gamma}$) can be calculated based on the equations:

[TABLE]

where $N_{\ttbar\text{+}\gamma}$ is the number of $\ttbar\text{+}\gamma$ events observed, $A^{\ttbar\text{+}\gamma}$ is the acceptance of $\ttbar\text{+}\gamma$ events within the fiducial phase space, $\epsilon^{\ttbar\text{+}\gamma}$ is the efficiency of the $\ttbar\text{+}\gamma$ selection within events in the acceptance region, and $L$ is the integrated luminosity of the data set.

The acceptance is determined at generator level, by requiring generated events to fall within the fiducial phase space defined for the analysis. Events are required to have exactly one generated prompt lepton in the fiducial phase space. For electrons, this requires $\pt>35$\GeVand $\abs{\eta}<2.5$ while not falling in the region $1.44<\abs{\eta}<1.56$. The visible phase space for muons is defined as $\pt>26$\GeVand $\abs{\eta}<2.5$. Events are required to have at least three generated jets with $\pt>30$\GeVand $\abs{\eta}<2.4$. In order to replicate the \ptmissrequirement, the vector sum of the \ptof generated neutrinos is required to be greater than 20\GeV. Lastly, events are required to have a generated photon with $\pt>25$\GeVand $\abs{\eta}<1.44$. The acceptance can be split into two components: the one coming from the branching fraction of $\ttbar\text{+}\gamma$ to the $\Pe\text{+jets}$ or $\Pgm\text{+jets}$ channels, and the one coming from the kinematic phase space requirements. The kinematic acceptance is measured by the number of events passing the kinematic phase space requirements described above divided by the number of events generated in the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final states.

The efficiency is calculated as the ratio of reconstructed events that pass the event selection over the number of events generated in the fiducial phase space. This accounts for the migration of events into and out of the fiducial phase space, and includes the efficiencies of the trigger requirement, object identification and reconstruction, and the event selection. The measured values for the acceptance and efficiency of the $\ttbar\text{+}\gamma$ selection in the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ channels are given in Table 0.10.

In order to reduce the effect of systematic uncertainties that similarly affect all $\ttbar\text{+jets}$ production modes, the ratio of the cross section of fiducial $\ttbar\text{+}\gamma$ production to the inclusive \ttbarproduction cross section is calculated as

[TABLE]

where $N_{\ttbar}$ is the number of \ttbarevents passing the top quark selection, and $\epsilon^{\ttbar}_{\text{top}}$ and $A^{\ttbar}_{\text{top}}$ are the efficiency and acceptance of top quark selection for \ttbarevents. The value of $\epsilon^{\ttbar}_{\text{top}}\,A^{\ttbar}_{\text{top}}$ is determined from simulation to be $0.034$ in the $\Pe\text{+jets}$ final state and $0.046$ in the $\Pgm\text{+jets}$ final state with negligible statistical uncertainties.

0.11 Sources of systematic uncertainty

The effects of the systematic uncertainties are estimated by varying the simulated samples according to the uncertainty and repeating the measurement. The top quark purity measurement, photon purity measurement, and likelihood fit are repeated for each source of systematic uncertainty and the new value of the cross section ratio is compared to the nominal value. In this way, an estimate of the effect each source of systematic uncertainty has on the final result is found. Table 0.11 lists the uncertainties in decreasing order of their effect on the cross section ratio, as found through the combination of the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final states.

The statistical uncertainty in the number of signal events found after maximizing the likelihood fit described in Section 0.9, dominates the determination of the cross section for $\ttbar\text{+}\gamma$. It includes the uncertainties in the measurement of the photon purity, top quark purity after photon selection, and the statistical uncertainty from the observed number of events in data. The contribution from each of these three portions is estimated individually by performing the likelihood fit in which the uncertainties in these parameters are set to zero one at a time. This effectively fixes the value to the measured value. The change in the $\mathrm{SF}_{\ttbar\text{+}\gamma}$ uncertainty (which is roughly 14% in the standard likelihood fit) can be attributed to the fixed parameter. The uncertainty is dominated by the top quark purity and photon purity uncertainties, which contribute 10% and 9%, respectively. The statistical uncertainty caused by the limited number of events in data is approximately 4.8%.

The uncertainties in the energy of reconstructed objects in the event are taken into account by scaling the energies of reconstructed objects in simulation up and down by the uncertainties in their corrections. The uncertainties in the jet energy scale (JES) and jet energy resolution (JER) [35] are applied to the reconstructed jets and the effect is propagated to the calculation of \ptmiss. Similarly the uncertainty due to the photon energy is found by scaling the energy of reconstructed photons up and down by 1%, and the measurement is repeated [12]. The uncertainty due to the lepton energy scale is found by varying the \ptof the electrons and muons in the event by 1% in the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final states, respectively [32, 39].

A 50% uncertainty is assigned to the normalization of the data-based multijet sample derived from the fit to the \ptmissdistributions. Additionally, a 20% normalization uncertainty is applied to the backgrounds that are fixed to their theoretical cross sections in the $M_{3}$ fit (described in Section 0.7). The systematic uncertainty due to the scale factor for $\Z\text{+jets}$ simulation (described in Section 0.6) is applied by adjusting the scale factor up and down by its uncertainty.

The uncertainty in the efficiency of the b tagging algorithm is taken into account by varying the b tagging scale factors up and down by their uncertainties [37]. Differences between the distribution of the \ptof the top quarks in data and simulation are taken into account by applying a reweighting based on the \ptof the generated top quarks and treating the difference from the nominal sample as a systematic uncertainty (“top quark \ptreweighting”) [40]. The uncertainty in the pileup correction is found by recalculating the pileup distribution in data with a plus and minus 5% change to the total inelastic proton-proton cross section [41], and using these new distributions to reweight the simulation.

The uncertainty in the factorization and renormalization scales is taken into account by simulating the $\ttbar\text{+}\gamma$ and $\ttbar\text{+jets}$ processes with the scales doubled and halved compared to the nominal value of $\mu_{\mathrm{F}}=\mu_{\mathrm{R}}=Q=\sqrt{\smash[b]{m^{2}_{\cPqt}+\Sigma\pt^{2}}}$ (where the sum is taken over all final state partons). The uncertainty in the matching of partons at ME level to the parton shower (PS) is found by simulating $\ttbar\text{+}\gamma$ and $\ttbar\text{+jets}$ processes with the threshold used for matching doubled and halved from the nominal value of 20\GeV. The uncertainty arising from the choice of the top quark mass used in simulation is measured by simulating the samples with a value of $m_{\PQt}$ varied up and down by 1\GeVfrom its central value of $m_{\PQt}=172.5$\GeV.

0.12 Results

The ratio of the fiducial cross section of $\ttbar\text{+}\gamma$ to \ttbarproduction is found to be $R=(5.7\pm 1.8)\times 10^{-4}\,(\text{stat+syst})$ in the $\Pe\text{+jets}$ final state and $R=(4.7\pm 1.3)\times 10^{-4}\,(\text{stat+syst})$ in the $\Pgm\text{+jets}$ final state. The value of the fiducial $\ttbar\text{+}\gamma$ cross section can be extracted from the cross section ratio using the measured \ttbarcross section of $244.9\pm 1.4\stat^{+6.3}_{-5.5}\syst\pm 6.4\lum$\unitpb [24]. Multiplying the cross section ratio by the measured \ttbarcross section results in values for the $\ttbar\text{+}\gamma$ fiducial cross section of $138\pm 45\,(\text{stat+syst})$\unitfb in the $\Pe\text{+jets}$ final state and $115\pm 32\,(\text{stat+syst})$\unitfb in the $\Pgm\text{+jets}$ final state.

The value of the cross section times the branching fraction in the lepton+jets final states can be extrapolated from the fiducial cross section by dividing by the kinematic acceptance. The kinematic acceptances (as given in Section 0.10) are found to be $0.2380\pm 0.0014$ and $0.2551\pm 0.0014$ in the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final states. This gives a cross section times branching fraction of $\sigma_{\ttbar\text{+}\gamma}\,\mathcal{B}=582\pm 187$\unitfb in the $\Pe\text{+jets}$ final state and $453\pm 124$\unitfb in the $\Pgm\text{+jets}$ final state. These values are in agreement with theoretical prediction of $592\pm 71(\text{scales})\pm 30\,(\text{PDFs})$\unitfb for the cross section times branching fraction of each of the semileptonic final states [42].

The combination of the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ channels results in a cross section ratio per semileptonic final state of $(5.2\pm 1.1)\times 10^{-4}\,(\text{stat+syst})$. This results in a value of $127\pm 27\,(\text{stat+syst})$\unitfb for the fiducial $\ttbar\text{+}\gamma$ cross section. When extrapolated to the cross section times branching fraction by dividing by the kinematic acceptance, the result is $\sigma_{\ttbar\text{+}\gamma}\,\mathcal{B}=515\pm 108$\unitfb per lepton+jets final state, in good agreement with the theoretical prediction. Table 0.12 summarizes the measured ratios and cross sections for the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final states as well as the combination.

The distributions of the transverse momentum and absolute value of the pseudorapidity of the photon candidate are shown in Figs. 7 and 8, scaled to the results of the likelihood fit. While the statistical precision of this analysis currently limits the ability to perform a differential measurement of the $\ttbar\text{+}\gamma$ cross section, there is the potential to measure the differential cross section in the future in both of these variables.

0.13 Summary

The results of a measurement of the production of a top quark-antiquark (\ttbar) pair produced in association with a photon have been presented. The measurement is performed using 19.7\fbinvof data collected by the CMS detector at a center-of-mass energy of 8\TeV. The analysis has been performed in the semileptonic $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ decay channels.

The ratio of the $\ttbar\text{+}\gamma$ to \ttbarproduction cross sections has been measured to be $R={\sigma_{\ttbar\text{+}\gamma}/\sigma_{\ttbar}}={(5.2\pm 1.1)\times 10^{-4}}$. By multiplying the measured ratio by the previously measured value of the \ttbarcross section, the fiducial cross section for $\ttbar\text{+}\gamma$ production of $127\pm 27$\unitfb has been found for events in the $\Pe\text{+jets}$ and $\Pgm\text{+jets}$ final states. The measured values are in agreement with the theoretical predictions.

Acknowledgements.

We congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC and thank the technical and administrative staffs at CERN and at other CMS institutes for their contributions to the success of the CMS effort. In addition, we gratefully acknowledge the computing centres and personnel of the Worldwide LHC Computing Grid for delivering so effectively the computing infrastructure essential to our analyses. Finally, we acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies: BMWFW and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); SENESCYT (Ecuador); MoER, ERC IUT, and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); BUAP, CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS, RFBR and RAEP (Russia); MESTD (Serbia); SEIDI, CPAN, PCTI and FEDER (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie programme and the European Research Council and Horizon 2020 Grant, contract No. 675440 (European Union); the Leventis Foundation; the A. P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Council of Science and Industrial Research, India; the HOMING PLUS programme of the Foundation for Polish Science, cofinanced from European Union, Regional Development Fund, the Mobility Plus programme of the Ministry of Science and Higher Education, the National Science Center (Poland), contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, and 2015/19/B/ST2/02861, Sonata-bis 2012/07/E/ST2/01406; the National Priorities Research Program by Qatar National Research Fund; the Programa Clarín-COFUND del Principado de Asturias; the Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF; the Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University and the Chulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand); and the Welch Foundation, contract C-1845.

.14 The CMS Collaboration

**Yerevan Physics Institute, Yerevan, Armenia

** A.M. Sirunyan, A. Tumasyan \cmsinstskip**Institut für Hochenergiephysik, Wien, Austria

** W. Adam, E. Asilar, T. Bergauer, J. Brandstetter, E. Brondolin, M. Dragicevic, J. Erö, M. Flechl, M. Friedl, R. Frühwirth\cmsAuthorMark1, V.M. Ghete, C. Hartl, N. Hörmann, J. Hrubec, M. Jeitler\cmsAuthorMark1, A. König, I. Krätschmer, D. Liko, T. Matsushita, I. Mikulec, D. Rabady, N. Rad, B. Rahbaran, H. Rohringer, J. Schieck\cmsAuthorMark1, J. Strauss, W. Waltenberger, C.-E. Wulz\cmsAuthorMark1 \cmsinstskip**Institute for Nuclear Problems, Minsk, Belarus

** O. Dvornikov, V. Makarenko, V. Mossolov, J. Suarez Gonzalez, V. Zykunov \cmsinstskip**National Centre for Particle and High Energy Physics, Minsk, Belarus

** N. Shumeiko \cmsinstskip**Universiteit Antwerpen, Antwerpen, Belgium

** S. Alderweireldt, E.A. De Wolf, X. Janssen, J. Lauwers, M. Van De Klundert, H. Van Haevermaet, P. Van Mechelen, N. Van Remortel, A. Van Spilbeeck \cmsinstskip**Vrije Universiteit Brussel, Brussel, Belgium

** S. Abu Zeid, F. Blekman, J. D’Hondt, N. Daci, I. De Bruyn, K. Deroover, S. Lowette, S. Moortgat, L. Moreels, A. Olbrechts, Q. Python, K. Skovpen, S. Tavernier, W. Van Doninck, P. Van Mulders, I. Van Parijs \cmsinstskip**Université Libre de Bruxelles, Bruxelles, Belgium

** H. Brun, B. Clerbaux, G. De Lentdecker, H. Delannoy, G. Fasanella, L. Favart, R. Goldouzian, A. Grebenyuk, G. Karapostoli, T. Lenzi, A. Léonard, J. Luetic, T. Maerschalk, A. Marinov, A. Randle-conde, T. Seva, C. Vander Velde, P. Vanlaer, D. Vannerom, R. Yonamine, F. Zenoni, F. Zhang\cmsAuthorMark2 \cmsinstskip**Ghent University, Ghent, Belgium

** A. Cimmino, T. Cornelis, D. Dobur, A. Fagot, M. Gul, I. Khvastunov, D. Poyraz, S. Salva, R. Schöfbeck, M. Tytgat, W. Van Driessche, E. Yazgan, N. Zaganidis \cmsinstskip**Université Catholique de Louvain, Louvain-la-Neuve, Belgium

** H. Bakhshiansohi, C. Beluffi\cmsAuthorMark3, O. Bondu, S. Brochet, G. Bruno, A. Caudron, S. De Visscher, C. Delaere, M. Delcourt, B. Francois, A. Giammanco, A. Jafari, M. Komm, G. Krintiras, V. Lemaitre, A. Magitteri, A. Mertens, M. Musich, K. Piotrzkowski, L. Quertenmont, M. Selvaggi, M. Vidal Marono, S. Wertz \cmsinstskip**Université de Mons, Mons, Belgium

** N. Beliy \cmsinstskip**Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil

** W.L. Aldá Júnior, F.L. Alves, G.A. Alves, L. Brito, C. Hensel, A. Moraes, M.E. Pol, P. Rebello Teles \cmsinstskip**Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil

** E. Belchior Batista Das Chagas, W. Carvalho, J. Chinellato\cmsAuthorMark4, A. Custódio, E.M. Da Costa, G.G. Da Silveira\cmsAuthorMark5, D. De Jesus Damiao, C. De Oliveira Martins, S. Fonseca De Souza, L.M. Huertas Guativa, H. Malbouisson, D. Matos Figueiredo, C. Mora Herrera, L. Mundim, H. Nogima, W.L. Prado Da Silva, A. Santoro, A. Sznajder, E.J. Tonelli Manganote\cmsAuthorMark4, F. Torres Da Silva De Araujo, A. Vilela Pereira \cmsinstskip**Universidade Estadual Paulista a,  Universidade Federal do ABC b,  São Paulo, Brazil

** S. Ahujaa, C.A. Bernardesa, S. Dograa, T.R. Fernandez Perez Tomeia, E.M. Gregoresb, P.G. Mercadanteb, C.S. Moona, S.F. Novaesa, Sandra S. Padulaa, D. Romero Abadb, J.C. Ruiz Vargasa \cmsinstskip**Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria

** A. Aleksandrov, R. Hadjiiska, P. Iaydjiev, M. Rodozov, S. Stoykova, G. Sultanov, M. Vutova \cmsinstskip**University of Sofia, Sofia, Bulgaria

** A. Dimitrov, I. Glushkov, L. Litov, B. Pavlov, P. Petkov \cmsinstskip**Beihang University, Beijing, China

** W. Fang\cmsAuthorMark6 \cmsinstskip**Institute of High Energy Physics, Beijing, China

** M. Ahmad, J.G. Bian, G.M. Chen, H.S. Chen, M. Chen, Y. Chen\cmsAuthorMark7, T. Cheng, C.H. Jiang, D. Leggat, Z. Liu, F. Romeo, M. Ruan, S.M. Shaheen, A. Spiezia, J. Tao, C. Wang, Z. Wang, H. Zhang, J. Zhao \cmsinstskip**State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China

** Y. Ban, G. Chen, Q. Li, S. Liu, Y. Mao, S.J. Qian, D. Wang, Z. Xu \cmsinstskip**Universidad de Los Andes, Bogota, Colombia

** C. Avila, A. Cabrera, L.F. Chaparro Sierra, C. Florez, J.P. Gomez, C.F. González Hernández, J.D. Ruiz Alvarez, J.C. Sanabria \cmsinstskip**University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, Split, Croatia

** N. Godinovic, D. Lelas, I. Puljak, P.M. Ribeiro Cipriano, T. Sculac \cmsinstskip**University of Split, Faculty of Science, Split, Croatia

** Z. Antunovic, M. Kovac \cmsinstskip**Institute Rudjer Boskovic, Zagreb, Croatia

** V. Brigljevic, D. Ferencek, K. Kadija, B. Mesic, T. Susa \cmsinstskip**University of Cyprus, Nicosia, Cyprus

** A. Attikis, G. Mavromanolakis, J. Mousa, C. Nicolaou, F. Ptochos, P.A. Razis, H. Rykaczewski, D. Tsiakkouri \cmsinstskip**Charles University, Prague, Czech Republic

** M. Finger\cmsAuthorMark8, M. Finger Jr.\cmsAuthorMark8 \cmsinstskip**Universidad San Francisco de Quito, Quito, Ecuador

** E. Carrera Jarrin \cmsinstskip**Academy of Scientific Research and Technology of the Arab Republic of Egypt, Egyptian Network of High Energy Physics, Cairo, Egypt

** E. El-khateeb\cmsAuthorMark9, S. Elgammal\cmsAuthorMark10, A. Mohamed\cmsAuthorMark11 \cmsinstskip**National Institute of Chemical Physics and Biophysics, Tallinn, Estonia

** M. Kadastik, L. Perrini, M. Raidal, A. Tiko, C. Veelken \cmsinstskip**Department of Physics, University of Helsinki, Helsinki, Finland

** P. Eerola, J. Pekkanen, M. Voutilainen \cmsinstskip**Helsinki Institute of Physics, Helsinki, Finland

** J. Härkönen, T. Järvinen, V. Karimäki, R. Kinnunen, T. Lampén, K. Lassila-Perini, S. Lehti, T. Lindén, P. Luukka, J. Tuominiemi, E. Tuovinen, L. Wendland \cmsinstskip**Lappeenranta University of Technology, Lappeenranta, Finland

** J. Talvitie, T. Tuuva \cmsinstskip**IRFU, CEA, Université Paris-Saclay, Gif-sur-Yvette, France

** M. Besancon, F. Couderc, M. Dejardin, D. Denegri, B. Fabbro, J.L. Faure, C. Favaro, F. Ferri, S. Ganjour, S. Ghosh, A. Givernaud, P. Gras, G. Hamel de Monchenault, P. Jarry, I. Kucher, E. Locci, M. Machet, J. Malcles, J. Rander, A. Rosowsky, M. Titov \cmsinstskip**Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Université Paris-Saclay, Palaiseau, France

** A. Abdulsalam, I. Antropov, S. Baffioni, F. Beaudette, P. Busson, L. Cadamuro, E. Chapon, C. Charlot, O. Davignon, R. Granier de Cassagnac, M. Jo, S. Lisniak, P. Miné, M. Nguyen, C. Ochando, G. Ortona, P. Paganini, P. Pigard, S. Regnard, R. Salerno, Y. Sirois, A.G. Stahl Leiton, T. Strebler, Y. Yilmaz, A. Zabi, A. Zghiche \cmsinstskip**Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France

** J.-L. Agram\cmsAuthorMark12, J. Andrea, A. Aubin, D. Bloch, J.-M. Brom, M. Buttignol, E.C. Chabert, N. Chanon, C. Collard, E. Conte\cmsAuthorMark12, X. Coubez, J.-C. Fontaine\cmsAuthorMark12, D. Gelé, U. Goerlach, A.-C. Le Bihan, P. Van Hove \cmsinstskip**Centre de Calcul de l’Institut National de Physique Nucleaire et de Physique des Particules, CNRS/IN2P3, Villeurbanne, France

** S. Gadrat \cmsinstskip**Université de Lyon, Université Claude Bernard Lyon 1,  CNRS-IN2P3, Institut de Physique Nucléaire de Lyon, Villeurbanne, France

** S. Beauceron, C. Bernet, G. Boudoul, C.A. Carrillo Montoya, R. Chierici, D. Contardo, B. Courbon, P. Depasse, H. El Mamouni, J. Fay, S. Gascon, M. Gouzevitch, G. Grenier, B. Ille, F. Lagarde, I.B. Laktineh, M. Lethuillier, L. Mirabito, A.L. Pequegnot, S. Perries, A. Popov\cmsAuthorMark13, D. Sabes, V. Sordini, M. Vander Donckt, P. Verdier, S. Viret \cmsinstskip**Georgian Technical University, Tbilisi, Georgia

** A. Khvedelidze\cmsAuthorMark8 \cmsinstskip**Tbilisi State University, Tbilisi, Georgia

** D. Lomidze \cmsinstskip**RWTH Aachen University, I. Physikalisches Institut, Aachen, Germany

** C. Autermann, S. Beranek, L. Feld, M.K. Kiesel, K. Klein, M. Lipinski, M. Preuten, C. Schomakers, J. Schulz, T. Verlage \cmsinstskip**RWTH Aachen University, III. Physikalisches Institut A,  Aachen, Germany

** A. Albert, M. Brodski, E. Dietz-Laursonn, D. Duchardt, M. Endres, M. Erdmann, S. Erdweg, T. Esch, R. Fischer, A. Güth, M. Hamer, T. Hebbeker, C. Heidemann, K. Hoepfner, S. Knutzen, M. Merschmeyer, A. Meyer, P. Millet, S. Mukherjee, M. Olschewski, K. Padeken, T. Pook, M. Radziej, H. Reithler, M. Rieger, F. Scheuch, L. Sonnenschein, D. Teyssier, S. Thüer \cmsinstskip**RWTH Aachen University, III. Physikalisches Institut B,  Aachen, Germany

** V. Cherepanov, G. Flügge, B. Kargoll, T. Kress, A. Künsken, J. Lingemann, T. Müller, A. Nehrkorn, A. Nowack, C. Pistone, O. Pooth, A. Stahl\cmsAuthorMark14 \cmsinstskip**Deutsches Elektronen-Synchrotron, Hamburg, Germany

** M. Aldaya Martin, T. Arndt, C. Asawatangtrakuldee, K. Beernaert, O. Behnke, U. Behrens, A.A. Bin Anuar, K. Borras\cmsAuthorMark15, A. Campbell, P. Connor, C. Contreras-Campana, F. Costanza, C. Diez Pardos, G. Dolinska, G. Eckerlin, D. Eckstein, T. Eichhorn, E. Eren, E. Gallo\cmsAuthorMark16, J. Garay Garcia, A. Geiser, A. Gizhko, J.M. Grados Luyando, A. Grohsjean, P. Gunnellini, A. Harb, J. Hauk, M. Hempel\cmsAuthorMark17, H. Jung, A. Kalogeropoulos, O. Karacheban\cmsAuthorMark17, M. Kasemann, J. Keaveney, C. Kleinwort, I. Korol, D. Krücker, W. Lange, A. Lelek, T. Lenz, J. Leonard, K. Lipka, A. Lobanov, W. Lohmann\cmsAuthorMark17, R. Mankel, I.-A. Melzer-Pellmann, A.B. Meyer, G. Mittag, J. Mnich, A. Mussgiller, D. Pitzl, R. Placakyte, A. Raspereza, B. Roland, M.Ö. Sahin, P. Saxena, T. Schoerner-Sadenius, S. Spannagel, N. Stefaniuk, G.P. Van Onsem, R. Walsh, C. Wissing \cmsinstskip**University of Hamburg, Hamburg, Germany

** V. Blobel, M. Centis Vignali, A.R. Draeger, T. Dreyer, E. Garutti, D. Gonzalez, J. Haller, M. Hoffmann, A. Junkes, R. Klanner, R. Kogler, N. Kovalchuk, T. Lapsien, I. Marchesini, D. Marconi, M. Meyer, M. Niedziela, D. Nowatschin, F. Pantaleo\cmsAuthorMark14, T. Peiffer, A. Perieanu, C. Scharf, P. Schleper, A. Schmidt, S. Schumann, J. Schwandt, H. Stadie, G. Steinbrück, F.M. Stober, M. Stöver, H. Tholen, D. Troendle, E. Usai, L. Vanelderen, A. Vanhoefer, B. Vormwald \cmsinstskip**Institut für Experimentelle Kernphysik, Karlsruhe, Germany

** M. Akbiyik, C. Barth, S. Baur, C. Baus, J. Berger, E. Butz, R. Caspart, T. Chwalek, F. Colombo, W. De Boer, A. Dierlamm, S. Fink, B. Freund, R. Friese, M. Giffels, A. Gilbert, P. Goldenzweig, D. Haitz, F. Hartmann\cmsAuthorMark14, S.M. Heindl, U. Husemann, I. Katkov\cmsAuthorMark13, S. Kudella, H. Mildner, M.U. Mozer, Th. Müller, M. Plagge, G. Quast, K. Rabbertz, S. Röcker, F. Roscher, M. Schröder, I. Shvetsov, G. Sieber, H.J. Simonis, R. Ulrich, S. Wayand, M. Weber, T. Weiler, S. Williamson, C. Wöhrmann, R. Wolf \cmsinstskip**Institute of Nuclear and Particle Physics (INPP),  NCSR Demokritos, Aghia Paraskevi, Greece

** G. Anagnostou, G. Daskalakis, T. Geralis, V.A. Giakoumopoulou, A. Kyriakis, D. Loukas, I. Topsis-Giotis \cmsinstskip**National and Kapodistrian University of Athens, Athens, Greece

** S. Kesisoglou, A. Panagiotou, N. Saoulidou, E. Tziaferi \cmsinstskip**University of Ioánnina, Ioánnina, Greece

** I. Evangelou, G. Flouris, C. Foudas, P. Kokkas, N. Loukas, N. Manthos, I. Papadopoulos, E. Paradas \cmsinstskip**MTA-ELTE Lendület CMS Particle and Nuclear Physics Group, Eötvös Loránd University, Budapest, Hungary

** N. Filipovic, G. Pasztor \cmsinstskip**Wigner Research Centre for Physics, Budapest, Hungary

** G. Bencze, C. Hajdu, D. Horvath\cmsAuthorMark18, F. Sikler, V. Veszpremi, G. Vesztergombi\cmsAuthorMark19, A.J. Zsigmond \cmsinstskip**Institute of Nuclear Research ATOMKI, Debrecen, Hungary

** N. Beni, S. Czellar, J. Karancsi\cmsAuthorMark20, A. Makovec, J. Molnar, Z. Szillasi \cmsinstskip**Institute of Physics, University of Debrecen, Debrecen, Hungary

** M. Bartók\cmsAuthorMark19, P. Raics, Z.L. Trocsanyi, B. Ujvari \cmsinstskip**Indian Institute of Science (IISc),  Bangalore, India

** J.R. Komaragiri \cmsinstskip**National Institute of Science Education and Research, Bhubaneswar, India

** S. Bahinipati\cmsAuthorMark21, S. Bhowmik\cmsAuthorMark22, S. Choudhury\cmsAuthorMark23, P. Mal, K. Mandal, A. Nayak\cmsAuthorMark24, D.K. Sahoo\cmsAuthorMark21, N. Sahoo, S.K. Swain \cmsinstskip**Panjab University, Chandigarh, India

** S. Bansal, S.B. Beri, V. Bhatnagar, U. Bhawandeep, R. Chawla, A.K. Kalsi, A. Kaur, M. Kaur, R. Kumar, P. Kumari, A. Mehta, M. Mittal, J.B. Singh, G. Walia \cmsinstskip**University of Delhi, Delhi, India

** Ashok Kumar, A. Bhardwaj, B.C. Choudhary, R.B. Garg, S. Keshri, S. Malhotra, M. Naimuddin, K. Ranjan, R. Sharma, V. Sharma \cmsinstskip**Saha Institute of Nuclear Physics, HBNI, Kolkata, India

** R. Bhattacharya, S. Bhattacharya, K. Chatterjee, S. Dey, S. Dutt, S. Dutta, S. Ghosh, N. Majumdar, A. Modak, K. Mondal, S. Mukhopadhyay, S. Nandan, A. Purohit, A. Roy, D. Roy, S. Roy Chowdhury, S. Sarkar, M. Sharan, S. Thakur \cmsinstskip**Indian Institute of Technology Madras, Madras, India

** P.K. Behera \cmsinstskip**Bhabha Atomic Research Centre, Mumbai, India

** R. Chudasama, D. Dutta, V. Jha, V. Kumar, A.K. Mohanty\cmsAuthorMark14, P.K. Netrakanti, L.M. Pant, P. Shukla, A. Topkar \cmsinstskip**Tata Institute of Fundamental Research-A, Mumbai, India

** T. Aziz, S. Dugad, G. Kole, B. Mahakud, S. Mitra, G.B. Mohanty, B. Parida, N. Sur, B. Sutar \cmsinstskip**Tata Institute of Fundamental Research-B, Mumbai, India

** S. Banerjee, R.K. Dewanjee, S. Ganguly, M. Guchait, Sa. Jain, S. Kumar, M. Maity\cmsAuthorMark22, G. Majumder, K. Mazumdar, T. Sarkar\cmsAuthorMark22, N. Wickramage\cmsAuthorMark25 \cmsinstskip**Indian Institute of Science Education and Research (IISER),  Pune, India

** S. Chauhan, S. Dube, V. Hegde, A. Kapoor, K. Kothekar, S. Pandey, A. Rane, S. Sharma \cmsinstskip**Institute for Research in Fundamental Sciences (IPM),  Tehran, Iran

** S. Chenarani\cmsAuthorMark26, E. Eskandari Tadavani, S.M. Etesami\cmsAuthorMark26, M. Khakzad, M. Mohammadi Najafabadi, M. Naseri, S. Paktinat Mehdiabadi\cmsAuthorMark27, F. Rezaei Hosseinabadi, B. Safarzadeh\cmsAuthorMark28, M. Zeinali \cmsinstskip**University College Dublin, Dublin, Ireland

** M. Felcini, M. Grunewald \cmsinstskip**INFN Sezione di Bari a, Università di Bari b, Politecnico di Bari c,  Bari, Italy

** M. Abbresciaa**,b, C. Calabriaa**,b, C. Caputoa**,b, A. Colaleoa, D. Creanzaa**,c, L. Cristellaa**,b, N. De Filippisa**,c, M. De Palmaa**,b, L. Fiorea, G. Iasellia**,c, G. Maggia**,c, M. Maggia, G. Minielloa**,b, S. Mya**,b, S. Nuzzoa**,b, A. Pompilia**,b, G. Pugliesea**,c, R. Radognaa**,b, A. Ranieria, G. Selvaggia**,b, A. Sharmaa, L. Silvestrisa**,\cmsAuthorMark14, R. Vendittia**,b, P. Verwilligena \cmsinstskip**INFN Sezione di Bologna a, Università di Bologna b,  Bologna, Italy

** G. Abbiendia, C. Battilana, D. Bonacorsia**,b, S. Braibant-Giacomellia**,b, L. Brigliadoria**,b, R. Campaninia**,b, P. Capiluppia**,b, A. Castroa**,b, F.R. Cavalloa, S.S. Chhibraa**,b, G. Codispotia**,b, M. Cuffiania**,b, G.M. Dallavallea, F. Fabbria, A. Fanfania**,b, D. Fasanellaa**,b, P. Giacomellia, C. Grandia, L. Guiduccia**,b, S. Marcellinia, G. Masettia, A. Montanaria, F.L. Navarriaa**,b, A. Perrottaa, A.M. Rossia**,b, T. Rovellia**,b, G.P. Sirolia**,b, N. Tosia**,b,\cmsAuthorMark14 \cmsinstskip**INFN Sezione di Catania a, Università di Catania b,  Catania, Italy

** S. Albergoa**,b, S. Costaa**,b, A. Di Mattiaa, F. Giordano*a**,b, R. Potenzaa**,b, A. Tricomia**,b, C. Tuvea**,*b \cmsinstskip**INFN Sezione di Firenze a, Università di Firenze b,  Firenze, Italy

** G. Barbaglia, V. Ciullia**,b, C. Civininia, R. D’Alessandroa**,b, E. Focardia**,b, P. Lenzia**,b, M. Meschinia, S. Paolettia, L. Russoa**,\cmsAuthorMark29, G. Sguazzonia, D. Stroma, L. Viliania**,b,\cmsAuthorMark14 \cmsinstskip**INFN Laboratori Nazionali di Frascati, Frascati, Italy

** L. Benussi, S. Bianco, F. Fabbri, D. Piccolo, F. Primavera\cmsAuthorMark14 \cmsinstskip**INFN Sezione di Genova a, Università di Genova b,  Genova, Italy

** V. Calvellia**,b, F. Ferroa, M.R. Mongea**,b, E. Robuttia, S. Tosi*a**,*b \cmsinstskip**INFN Sezione di Milano-Bicocca a, Università di Milano-Bicocca b,  Milano, Italy

** L. Brianzaa**,b,\cmsAuthorMark14, F. Brivioa**,b, V. Ciriolo, M.E. Dinardoa**,b, S. Fiorendia**,b,\cmsAuthorMark14, S. Gennaia, A. Ghezzia**,b, P. Govonia**,b, M. Malbertia**,b, S. Malvezzia, R.A. Manzonia**,b, D. Menascea, L. Moronia, M. Paganonia**,b, D. Pedrinia, S. Pigazzini*a**,b, S. Ragazzia**,b, T. Tabarelli de Fatisa**,*b \cmsinstskip**INFN Sezione di Napoli a, Università di Napoli ’Federico II’ b, Napoli, Italy, Università della Basilicata c, Potenza, Italy, Università G. Marconi d, Roma, Italy

** S. Buontempoa, N. Cavalloa**,c, G. De Nardo, S. Di Guidaa**,d,\cmsAuthorMark14, M. Espositoa**,b, F. Fabozzia**,c, F. Fiengaa**,b, A.O.M. Iorioa**,b, G. Lanzaa, L. Listaa, S. Meolaa**,d,\cmsAuthorMark14, P. Paoluccia**,\cmsAuthorMark14, C. Sciaccaa**,b, F. Thyssena \cmsinstskip**INFN Sezione di Padova a, Università di Padova b, Padova, Italy, Università di Trento c, Trento, Italy

** P. Azzia**,\cmsAuthorMark14, N. Bacchettaa, L. Benatoa**,b, D. Biselloa**,b, A. Bolettia**,b, R. Carlina**,b, A. Carvalho Antunes De Oliveiraa**,b, P. Checchiaa, M. Dall’Ossoa**,b, P. De Castro Manzanoa, T. Dorigoa, F. Fanzagoa, F. Gasparinia**,b, F. Gonellaa, S. Lacapraraa, M. Margonia**,b, A.T. Meneguzzoa**,b, J. Pazzinia**,b, N. Pozzobona**,b, P. Ronchesea**,b, F. Simonettoa**,b, E. Torassaa, S. Venturaa, M. Zanetti*a**,b, P. Zottoa**,b, G. Zumerlea**,*b \cmsinstskip**INFN Sezione di Pavia a, Università di Pavia b,  Pavia, Italy

** A. Braghieria, F. Fallavollitaa**,b, A. Magnania**,b, P. Montagnaa**,b, S.P. Rattia**,b, V. Rea, C. Riccardia**,b, P. Salvinia, I. Vai*a**,b, P. Vituloa**,*b \cmsinstskip**INFN Sezione di Perugia a, Università di Perugia b,  Perugia, Italy

** L. Alunni Solestizia**,b, G.M. Bileia, D. Ciangottinia**,b, L. Fanòa**,b, P. Laricciaa**,b, R. Leonardia**,b, G. Mantovania**,b, V. Mariania**,b, M. Menichellia, A. Sahaa, A. Santocchia*a**,*b \cmsinstskip**INFN Sezione di Pisa a, Università di Pisa b, Scuola Normale Superiore di Pisa c,  Pisa, Italy

** K. Androsova**,\cmsAuthorMark29, P. Azzurria**,\cmsAuthorMark14, G. Bagliesia, J. Bernardinia, T. Boccalia, R. Castaldia, M.A. Cioccia**,\cmsAuthorMark29, R. Dell’Orsoa, S. Donatoa**,c, G. Fedi, A. Giassia, M.T. Grippoa**,\cmsAuthorMark29, F. Ligabuea**,c, T. Lomtadzea, L. Martinia**,b, A. Messineoa**,b, F. Pallaa, A. Rizzia**,b, A. Savoy-Navarroa**,\cmsAuthorMark30, P. Spagnoloa, R. Tenchinia, G. Tonellia**,b, A. Venturia, P.G. Verdinia \cmsinstskip**INFN Sezione di Roma a, Sapienza Università di Roma b,  Rome, Italy

** L. Baronea**,b, F. Cavallaria, M. Cipriania**,b, D. Del Rea**,b,\cmsAuthorMark14, M. Diemoza, S. Gellia**,b, E. Longoa**,b, F. Margarolia**,b, B. Marzocchia**,b, P. Meridiania, G. Organtinia**,b, R. Paramattia, F. Preiatoa**,b, S. Rahatloua**,b, C. Rovellia, F. Santanastasio*a**,*b \cmsinstskip**INFN Sezione di Torino a, Università di Torino b, Torino, Italy, Università del Piemonte Orientale c, Novara, Italy

** N. Amapanea**,b, R. Arcidiaconoa**,c,\cmsAuthorMark14, S. Argiroa**,b, M. Arneodoa**,c, N. Bartosika, R. Bellana**,b, C. Biinoa, N. Cartigliaa, F. Cennaa**,b, M. Costaa**,b, R. Covarellia**,b, A. Deganoa**,b, N. Demariaa, L. Fincoa**,b, B. Kiania**,b, C. Mariottia, S. Masellia, E. Migliorea**,b, V. Monacoa**,b, E. Monteila**,b, M. Montenoa, M.M. Obertinoa**,b, L. Pachera**,b, N. Pastronea, M. Pelliccionia, G.L. Pinna Angionia**,b, F. Raveraa**,b, A. Romeroa**,b, M. Ruspaa**,c, R. Sacchia**,b, K. Shchelinaa**,b, V. Solaa, A. Solanoa**,b, A. Staianoa, P. Traczyk*a**,*b \cmsinstskip**INFN Sezione di Trieste a, Università di Trieste b,  Trieste, Italy

** S. Belfortea, M. Casarsaa, F. Cossuttia, G. Della Riccaa**,b, A. Zanettia \cmsinstskip**Kyungpook National University, Daegu, Korea

** D.H. Kim, G.N. Kim, M.S. Kim, S. Lee, S.W. Lee, Y.D. Oh, S. Sekmen, D.C. Son, Y.C. Yang \cmsinstskip**Chonbuk National University, Jeonju, Korea

** A. Lee \cmsinstskip**Chonnam National University, Institute for Universe and Elementary Particles, Kwangju, Korea

** H. Kim \cmsinstskip**Hanyang University, Seoul, Korea

** J.A. Brochero Cifuentes, T.J. Kim \cmsinstskip**Korea University, Seoul, Korea

** S. Cho, S. Choi, Y. Go, D. Gyun, S. Ha, B. Hong, Y. Jo, Y. Kim, K. Lee, K.S. Lee, S. Lee, J. Lim, S.K. Park, Y. Roh \cmsinstskip**Seoul National University, Seoul, Korea

** J. Almond, J. Kim, H. Lee, S.B. Oh, B.C. Radburn-Smith, S.h. Seo, U.K. Yang, H.D. Yoo, G.B. Yu \cmsinstskip**University of Seoul, Seoul, Korea

** M. Choi, H. Kim, J.H. Kim, J.S.H. Lee, I.C. Park, G. Ryu, M.S. Ryu \cmsinstskip**Sungkyunkwan University, Suwon, Korea

** Y. Choi, J. Goh, C. Hwang, J. Lee, I. Yu \cmsinstskip**Vilnius University, Vilnius, Lithuania

** V. Dudenas, A. Juodagalvis, J. Vaitkus \cmsinstskip**National Centre for Particle Physics, Universiti Malaya, Kuala Lumpur, Malaysia

** I. Ahmed, Z.A. Ibrahim, M.A.B. Md Ali\cmsAuthorMark31, F. Mohamad Idris\cmsAuthorMark32, W.A.T. Wan Abdullah, M.N. Yusli, Z. Zolkapli \cmsinstskip**Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico

** H. Castilla-Valdez, E. De La Cruz-Burelo, I. Heredia-De La Cruz\cmsAuthorMark33, A. Hernandez-Almada, R. Lopez-Fernandez, R. Magaña Villalba, J. Mejia Guisao, A. Sanchez-Hernandez \cmsinstskip**Universidad Iberoamericana, Mexico City, Mexico

** S. Carrillo Moreno, C. Oropeza Barrera, F. Vazquez Valencia \cmsinstskip**Benemerita Universidad Autonoma de Puebla, Puebla, Mexico

** S. Carpinteyro, I. Pedraza, H.A. Salazar Ibarguen, C. Uribe Estrada \cmsinstskip**Universidad Autónoma de San Luis Potosí,  San Luis Potosí,  Mexico

** A. Morelos Pineda \cmsinstskip**University of Auckland, Auckland, New Zealand

** D. Krofcheck \cmsinstskip**University of Canterbury, Christchurch, New Zealand

** P.H. Butler \cmsinstskip**National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan

** A. Ahmad, M. Ahmad, Q. Hassan, H.R. Hoorani, W.A. Khan, A. Saddique, M.A. Shah, M. Shoaib, M. Waqas \cmsinstskip**National Centre for Nuclear Research, Swierk, Poland

** H. Bialkowska, M. Bluj, B. Boimska, T. Frueboes, M. Górski, M. Kazana, K. Nawrocki, K. Romanowska-Rybinska, M. Szleper, P. Zalewski \cmsinstskip**Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland

** K. Bunkowski, A. Byszuk\cmsAuthorMark34, K. Doroba, A. Kalinowski, M. Konecki, J. Krolikowski, M. Misiura, M. Olszewski, M. Walczak \cmsinstskip**Laboratório de Instrumentação e Física Experimental de Partículas, Lisboa, Portugal

** P. Bargassa, C. Beirão Da Cruz E Silva, B. Calpas, A. Di Francesco, P. Faccioli, P.G. Ferreira Parracho, M. Gallinaro, J. Hollar, N. Leonardo, L. Lloret Iglesias, M.V. Nemallapudi, J. Rodrigues Antunes, J. Seixas, O. Toldaiev, D. Vadruccio, J. Varela \cmsinstskip**Joint Institute for Nuclear Research, Dubna, Russia

** S. Afanasiev, P. Bunin, M. Gavrilenko, I. Golutvin, I. Gorbunov, A. Kamenev, V. Karjavin, A. Lanev, A. Malakhov, V. Matveev\cmsAuthorMark35*,*\cmsAuthorMark36, V. Palichik, V. Perelygin, S. Shmatov, S. Shulha, N. Skatchkov, V. Smirnov, N. Voytishin, A. Zarubin \cmsinstskip**Petersburg Nuclear Physics Institute, Gatchina (St. Petersburg),  Russia

** L. Chtchipounov, V. Golovtsov, Y. Ivanov, V. Kim\cmsAuthorMark37, E. Kuznetsova\cmsAuthorMark38, V. Murzin, V. Oreshkin, V. Sulimov, A. Vorobyev \cmsinstskip**Institute for Nuclear Research, Moscow, Russia

** Yu. Andreev, A. Dermenev, S. Gninenko, N. Golubev, A. Karneyeu, M. Kirsanov, N. Krasnikov, A. Pashenkov, D. Tlisov, A. Toropin \cmsinstskip**Institute for Theoretical and Experimental Physics, Moscow, Russia

** V. Epshteyn, V. Gavrilov, N. Lychkovskaya, V. Popov, I. Pozdnyakov, G. Safronov, A. Spiridonov, M. Toms, E. Vlasov, A. Zhokin \cmsinstskip**Moscow Institute of Physics and Technology, Moscow, Russia

** T. Aushev, A. Bylinkin\cmsAuthorMark36 \cmsinstskip**National Research Nuclear University ’Moscow Engineering Physics Institute’ (MEPhI),  Moscow, Russia

** R. Chistov\cmsAuthorMark39, M. Danilov\cmsAuthorMark39, V. Rusinov \cmsinstskip**P.N. Lebedev Physical Institute, Moscow, Russia

** V. Andreev, M. Azarkin\cmsAuthorMark36, I. Dremin\cmsAuthorMark36, M. Kirakosyan, A. Leonidov\cmsAuthorMark36, A. Terkulov \cmsinstskip**Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia

** A. Baskakov, A. Belyaev, E. Boos, V. Bunichev, M. Dubinin\cmsAuthorMark40, L. Dudko, V. Klyukhin, O. Kodolova, N. Korneeva, I. Lokhtin, I. Miagkov, S. Obraztsov, M. Perfilov, V. Savrin, P. Volkov \cmsinstskip**Novosibirsk State University (NSU),  Novosibirsk, Russia

** V. Blinov\cmsAuthorMark41, Y.Skovpen\cmsAuthorMark41, D. Shtol\cmsAuthorMark41 \cmsinstskip**State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, Russia

** I. Azhgirey, I. Bayshev, S. Bitioukov, D. Elumakhov, V. Kachanov, A. Kalinin, D. Konstantinov, V. Krychkine, V. Petrov, R. Ryutin, A. Sobol, S. Troshin, N. Tyurin, A. Uzunian, A. Volkov \cmsinstskip**University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia

** P. Adzic\cmsAuthorMark42, P. Cirkovic, D. Devetak, M. Dordevic, J. Milosevic, V. Rekovic \cmsinstskip**Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT),  Madrid, Spain

** J. Alcaraz Maestre, M. Barrio Luna, E. Calvo, M. Cerrada, M. Chamizo Llatas, N. Colino, B. De La Cruz, A. Delgado Peris, A. Escalante Del Valle, C. Fernandez Bedoya, J.P. Fernández Ramos, J. Flix, M.C. Fouz, P. Garcia-Abia, O. Gonzalez Lopez, S. Goy Lopez, J.M. Hernandez, M.I. Josa, E. Navarro De Martino, A. Pérez-Calero Yzquierdo, J. Puerta Pelayo, A. Quintario Olmeda, I. Redondo, L. Romero, M.S. Soares \cmsinstskip**Universidad Autónoma de Madrid, Madrid, Spain

** J.F. de Trocóniz, M. Missiroli, D. Moran \cmsinstskip**Universidad de Oviedo, Oviedo, Spain

** J. Cuevas, J. Fernandez Menendez, I. Gonzalez Caballero, J.R. González Fernández, E. Palencia Cortezon, S. Sanchez Cruz, I. Suárez Andrés, P. Vischia, J.M. Vizan Garcia \cmsinstskip**Instituto de Física de Cantabria (IFCA),  CSIC-Universidad de Cantabria, Santander, Spain

** I.J. Cabrillo, A. Calderon, E. Curras, M. Fernandez, J. Garcia-Ferrero, G. Gomez, A. Lopez Virto, J. Marco, C. Martinez Rivero, F. Matorras, J. Piedra Gomez, T. Rodrigo, A. Ruiz-Jimeno, L. Scodellaro, N. Trevisani, I. Vila, R. Vilar Cortabitarte \cmsinstskip**CERN, European Organization for Nuclear Research, Geneva, Switzerland

** D. Abbaneo, E. Auffray, G. Auzinger, P. Baillon, A.H. Ball, D. Barney, P. Bloch, A. Bocci, C. Botta, T. Camporesi, R. Castello, M. Cepeda, G. Cerminara, Y. Chen, D. d’Enterria, A. Dabrowski, V. Daponte, A. David, M. De Gruttola, A. De Roeck, E. Di Marco\cmsAuthorMark43, M. Dobson, B. Dorney, T. du Pree, D. Duggan, M. Dünser, N. Dupont, A. Elliott-Peisert, P. Everaerts, S. Fartoukh, G. Franzoni, J. Fulcher, W. Funk, D. Gigi, K. Gill, M. Girone, F. Glege, D. Gulhan, S. Gundacker, M. Guthoff, P. Harris, J. Hegeman, V. Innocente, P. Janot, J. Kieseler, H. Kirschenmann, V. Knünz, A. Kornmayer\cmsAuthorMark14, M.J. Kortelainen, K. Kousouris, M. Krammer\cmsAuthorMark1, C. Lange, P. Lecoq, C. Lourenço, M.T. Lucchini, L. Malgeri, M. Mannelli, A. Martelli, F. Meijers, J.A. Merlin, S. Mersi, E. Meschi, P. Milenovic\cmsAuthorMark44, F. Moortgat, S. Morovic, M. Mulders, H. Neugebauer, S. Orfanelli, L. Orsini, L. Pape, E. Perez, M. Peruzzi, A. Petrilli, G. Petrucciani, A. Pfeiffer, M. Pierini, A. Racz, T. Reis, G. Rolandi\cmsAuthorMark45, M. Rovere, H. Sakulin, J.B. Sauvan, C. Schäfer, C. Schwick, M. Seidel, A. Sharma, P. Silva, P. Sphicas\cmsAuthorMark46, J. Steggemann, M. Stoye, Y. Takahashi, M. Tosi, D. Treille, A. Triossi, A. Tsirou, V. Veckalns\cmsAuthorMark47, G.I. Veres\cmsAuthorMark19, M. Verweij, N. Wardle, H.K. Wöhri, A. Zagozdzinska\cmsAuthorMark34, W.D. Zeuner \cmsinstskip**Paul Scherrer Institut, Villigen, Switzerland

** W. Bertl, K. Deiters, W. Erdmann, R. Horisberger, Q. Ingram, H.C. Kaestli, D. Kotlinski, U. Langenegger, T. Rohe, S.A. Wiederkehr \cmsinstskip**Institute for Particle Physics, ETH Zurich, Zurich, Switzerland

** F. Bachmair, L. Bäni, L. Bianchini, B. Casal, G. Dissertori, M. Dittmar, M. Donegà, C. Grab, C. Heidegger, D. Hits, J. Hoss, G. Kasieczka, W. Lustermann, B. Mangano, M. Marionneau, P. Martinez Ruiz del Arbol, M. Masciovecchio, M.T. Meinhard, D. Meister, F. Micheli, P. Musella, F. Nessi-Tedaldi, F. Pandolfi, J. Pata, F. Pauss, G. Perrin, L. Perrozzi, M. Quittnat, M. Rossini, M. Schönenberger, A. Starodumov\cmsAuthorMark48, V.R. Tavolaro, K. Theofilatos, R. Wallny \cmsinstskip**Universität Zürich, Zurich, Switzerland

** T.K. Aarrestad, C. Amsler\cmsAuthorMark49, L. Caminada, M.F. Canelli, A. De Cosa, C. Galloni, A. Hinzmann, T. Hreus, B. Kilminster, J. Ngadiuba, D. Pinna, G. Rauco, P. Robmann, D. Salerno, C. Seitz, Y. Yang, A. Zucchetta \cmsinstskip**National Central University, Chung-Li, Taiwan

** V. Candelise, T.H. Doan, Sh. Jain, R. Khurana, M. Konyushikhin, C.M. Kuo, W. Lin, A. Pozdnyakov, S.S. Yu \cmsinstskip**National Taiwan University (NTU),  Taipei, Taiwan

** Arun Kumar, P. Chang, Y.H. Chang, Y. Chao, K.F. Chen, P.H. Chen, F. Fiori, W.-S. Hou, Y. Hsiung, Y.F. Liu, R.-S. Lu, M. Miñano Moya, E. Paganis, A. Psallidas, J.f. Tsai \cmsinstskip**Chulalongkorn University, Faculty of Science, Department of Physics, Bangkok, Thailand

** B. Asavapibhop, G. Singh, N. Srimanobhas, N. Suwonjandee \cmsinstskip**Cukurova University, Physics Department, Science and Art Faculty, Adana, Turkey

** A. Adiguzel, S. Cerci\cmsAuthorMark50, S. Damarseckin, Z.S. Demiroglu, C. Dozen, I. Dumanoglu, S. Girgis, G. Gokbulut, Y. Guler, I. Hos\cmsAuthorMark51, E.E. Kangal\cmsAuthorMark52, O. Kara, U. Kiminsu, M. Oglakci, G. Onengut\cmsAuthorMark53, K. Ozdemir\cmsAuthorMark54, D. Sunar Cerci\cmsAuthorMark50, B. Tali\cmsAuthorMark50, H. Topakli\cmsAuthorMark55, S. Turkcapar, I.S. Zorbakir, C. Zorbilmez \cmsinstskip**Middle East Technical University, Physics Department, Ankara, Turkey

** B. Bilin, S. Bilmis, B. Isildak\cmsAuthorMark56, G. Karapinar\cmsAuthorMark57, M. Yalvac, M. Zeyrek \cmsinstskip**Bogazici University, Istanbul, Turkey

** E. Gülmez, M. Kaya\cmsAuthorMark58, O. Kaya\cmsAuthorMark59, E.A. Yetkin\cmsAuthorMark60, T. Yetkin\cmsAuthorMark61 \cmsinstskip**Istanbul Technical University, Istanbul, Turkey

** A. Cakir, K. Cankocak, S. Sen\cmsAuthorMark62 \cmsinstskip**Institute for Scintillation Materials of National Academy of Science of Ukraine, Kharkov, Ukraine

** B. Grynyov \cmsinstskip**National Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, Ukraine

** L. Levchuk, P. Sorokin \cmsinstskip**University of Bristol, Bristol, United Kingdom

** R. Aggleton, F. Ball, L. Beck, J.J. Brooke, D. Burns, E. Clement, D. Cussans, H. Flacher, J. Goldstein, M. Grimes, G.P. Heath, H.F. Heath, J. Jacob, L. Kreczko, C. Lucas, D.M. Newbold\cmsAuthorMark63, S. Paramesvaran, A. Poll, T. Sakuma, S. Seif El Nasr-storey, D. Smith, V.J. Smith \cmsinstskip**Rutherford Appleton Laboratory, Didcot, United Kingdom

** K.W. Bell, A. Belyaev\cmsAuthorMark64, C. Brew, R.M. Brown, L. Calligaris, D. Cieri, D.J.A. Cockerill, J.A. Coughlan, K. Harder, S. Harper, E. Olaiya, D. Petyt, C.H. Shepherd-Themistocleous, A. Thea, I.R. Tomalin, T. Williams \cmsinstskip**Imperial College, London, United Kingdom

** M. Baber, R. Bainbridge, O. Buchmuller, A. Bundock, D. Burton, S. Casasso, M. Citron, D. Colling, L. Corpe, P. Dauncey, G. Davies, A. De Wit, M. Della Negra, R. Di Maria, P. Dunne, A. Elwood, D. Futyan, Y. Haddad, G. Hall, G. Iles, T. James, R. Lane, C. Laner, R. Lucas\cmsAuthorMark63, L. Lyons, A.-M. Magnan, S. Malik, L. Mastrolorenzo, J. Nash, A. Nikitenko\cmsAuthorMark48, J. Pela, B. Penning, M. Pesaresi, D.M. Raymond, A. Richards, A. Rose, E. Scott, C. Seez, S. Summers, A. Tapper, K. Uchida, M. Vazquez Acosta\cmsAuthorMark65, T. Virdee\cmsAuthorMark14, J. Wright, S.C. Zenz \cmsinstskip**Brunel University, Uxbridge, United Kingdom

** J.E. Cole, P.R. Hobson, A. Khan, P. Kyberd, I.D. Reid, P. Symonds, L. Teodorescu, M. Turner \cmsinstskip**Baylor University, Waco, USA

** A. Borzou, K. Call, J. Dittmann, K. Hatakeyama, H. Liu, N. Pastika \cmsinstskip**Catholic University of America, Washington, USA

** R. Bartek, A. Dominguez \cmsinstskip**The University of Alabama, Tuscaloosa, USA

** A. Buccilli, S.I. Cooper, C. Henderson, P. Rumerio, C. West \cmsinstskip**Boston University, Boston, USA

** D. Arcaro, A. Avetisyan, T. Bose, D. Gastler, D. Rankin, C. Richardson, J. Rohlf, L. Sulak, D. Zou \cmsinstskip**Brown University, Providence, USA

** G. Benelli, D. Cutts, A. Garabedian, J. Hakala, U. Heintz, J.M. Hogan, O. Jesus, K.H.M. Kwok, E. Laird, G. Landsberg, Z. Mao, M. Narain, S. Piperov, S. Sagir, E. Spencer, R. Syarif \cmsinstskip**University of California, Davis, Davis, USA

** R. Breedon, D. Burns, M. Calderon De La Barca Sanchez, S. Chauhan, M. Chertok, J. Conway, R. Conway, P.T. Cox, R. Erbacher, C. Flores, G. Funk, M. Gardner, W. Ko, R. Lander, C. Mclean, M. Mulhearn, D. Pellett, J. Pilot, S. Shalhout, M. Shi, J. Smith, M. Squires, D. Stolp, K. Tos, M. Tripathi \cmsinstskip**University of California, Los Angeles, USA

** M. Bachtis, C. Bravo, R. Cousins, A. Dasgupta, A. Florent, J. Hauser, M. Ignatenko, N. Mccoll, D. Saltzberg, C. Schnaible, V. Valuev, M. Weber \cmsinstskip**University of California, Riverside, Riverside, USA

** E. Bouvier, K. Burt, R. Clare, J. Ellison, J.W. Gary, S.M.A. Ghiasi Shirazi, G. Hanson, J. Heilman, P. Jandir, E. Kennedy, F. Lacroix, O.R. Long, M. Olmedo Negrete, M.I. Paneva, A. Shrinivas, W. Si, H. Wei, S. Wimpenny, B. R. Yates \cmsinstskip**University of California, San Diego, La Jolla, USA

** J.G. Branson, G.B. Cerati, S. Cittolin, M. Derdzinski, R. Gerosa, A. Holzner, D. Klein, V. Krutelyov, J. Letts, I. Macneill, D. Olivito, S. Padhi, M. Pieri, M. Sani, V. Sharma, S. Simon, M. Tadel, A. Vartak, S. Wasserbaech\cmsAuthorMark66, C. Welke, J. Wood, F. Würthwein, A. Yagil, G. Zevi Della Porta \cmsinstskip**University of California, Santa Barbara - Department of Physics, Santa Barbara, USA

** N. Amin, R. Bhandari, J. Bradmiller-Feld, C. Campagnari, A. Dishaw, V. Dutta, M. Franco Sevilla, C. George, F. Golf, L. Gouskos, J. Gran, R. Heller, J. Incandela, S.D. Mullin, A. Ovcharova, H. Qu, J. Richman, D. Stuart, I. Suarez, J. Yoo \cmsinstskip**California Institute of Technology, Pasadena, USA

** D. Anderson, J. Bendavid, A. Bornheim, J. Bunn, J. Duarte, J.M. Lawhorn, A. Mott, H.B. Newman, C. Pena, M. Spiropulu, J.R. Vlimant, S. Xie, R.Y. Zhu \cmsinstskip**Carnegie Mellon University, Pittsburgh, USA

** M.B. Andrews, T. Ferguson, M. Paulini, J. Russ, M. Sun, H. Vogel, I. Vorobiev, M. Weinberg \cmsinstskip**University of Colorado Boulder, Boulder, USA

** J.P. Cumalat, W.T. Ford, F. Jensen, A. Johnson, M. Krohn, S. Leontsinis, T. Mulholland, K. Stenson, S.R. Wagner \cmsinstskip**Cornell University, Ithaca, USA

** J. Alexander, J. Chaves, J. Chu, S. Dittmer, K. Mcdermott, N. Mirman, G. Nicolas Kaufman, J.R. Patterson, A. Rinkevicius, A. Ryd, L. Skinnari, L. Soffi, S.M. Tan, Z. Tao, J. Thom, J. Tucker, P. Wittich, M. Zientek \cmsinstskip**Fairfield University, Fairfield, USA

** D. Winn \cmsinstskip**Fermi National Accelerator Laboratory, Batavia, USA

** S. Abdullin, M. Albrow, G. Apollinari, A. Apresyan, S. Banerjee, L.A.T. Bauerdick, A. Beretvas, J. Berryhill, P.C. Bhat, G. Bolla, K. Burkett, J.N. Butler, H.W.K. Cheung, F. Chlebana, S. Cihangir${}^{\textrm{\textdagger}}$, M. Cremonesi, V.D. Elvira, I. Fisk, J. Freeman, E. Gottschalk, L. Gray, D. Green, S. Grünendahl, O. Gutsche, D. Hare, R.M. Harris, S. Hasegawa, J. Hirschauer, Z. Hu, B. Jayatilaka, S. Jindariani, M. Johnson, U. Joshi, B. Klima, B. Kreis, S. Lammel, J. Linacre, D. Lincoln, R. Lipton, M. Liu, T. Liu, R. Lopes De Sá, J. Lykken, K. Maeshima, N. Magini, J.M. Marraffino, S. Maruyama, D. Mason, P. McBride, P. Merkel, S. Mrenna, S. Nahn, V. O’Dell, K. Pedro, O. Prokofyev, G. Rakness, L. Ristori, E. Sexton-Kennedy, A. Soha, W.J. Spalding, L. Spiegel, S. Stoynev, J. Strait, N. Strobbe, L. Taylor, S. Tkaczyk, N.V. Tran, L. Uplegger, E.W. Vaandering, C. Vernieri, M. Verzocchi, R. Vidal, M. Wang, H.A. Weber, A. Whitbeck, Y. Wu \cmsinstskip**University of Florida, Gainesville, USA

** D. Acosta, P. Avery, P. Bortignon, D. Bourilkov, A. Brinkerhoff, A. Carnes, M. Carver, D. Curry, S. Das, R.D. Field, I.K. Furic, J. Konigsberg, A. Korytov, J.F. Low, P. Ma, K. Matchev, H. Mei, G. Mitselmakher, D. Rank, L. Shchutska, D. Sperka, L. Thomas, J. Wang, S. Wang, J. Yelton \cmsinstskip**Florida International University, Miami, USA

** S. Linn, P. Markowitz, G. Martinez, J.L. Rodriguez \cmsinstskip**Florida State University, Tallahassee, USA

** A. Ackert, T. Adams, A. Askew, S. Bein, S. Hagopian, V. Hagopian, K.F. Johnson, T. Kolberg, H. Prosper, A. Santra, R. Yohay \cmsinstskip**Florida Institute of Technology, Melbourne, USA

** M.M. Baarmand, V. Bhopatkar, S. Colafranceschi, M. Hohlmann, D. Noonan, T. Roy, F. Yumiceva \cmsinstskip**University of Illinois at Chicago (UIC),  Chicago, USA

** M.R. Adams, L. Apanasevich, D. Berry, R.R. Betts, I. Bucinskaite, R. Cavanaugh, O. Evdokimov, L. Gauthier, C.E. Gerber, D.J. Hofman, K. Jung, I.D. Sandoval Gonzalez, N. Varelas, H. Wang, Z. Wu, M. Zakaria, J. Zhang \cmsinstskip**The University of Iowa, Iowa City, USA

** B. Bilki\cmsAuthorMark67, W. Clarida, K. Dilsiz, S. Durgut, R.P. Gandrajula, M. Haytmyradov, V. Khristenko, J.-P. Merlo, H. Mermerkaya\cmsAuthorMark68, A. Mestvirishvili, A. Moeller, J. Nachtman, H. Ogul, Y. Onel, F. Ozok\cmsAuthorMark69, A. Penzo, C. Snyder, E. Tiras, J. Wetzel, K. Yi \cmsinstskip**Johns Hopkins University, Baltimore, USA

** B. Blumenfeld, A. Cocoros, N. Eminizer, D. Fehling, L. Feng, A.V. Gritsan, P. Maksimovic, J. Roskes, U. Sarica, M. Swartz, M. Xiao, C. You \cmsinstskip**The University of Kansas, Lawrence, USA

** A. Al-bataineh, P. Baringer, A. Bean, S. Boren, J. Bowen, J. Castle, L. Forthomme, R.P. Kenny III, S. Khalil, A. Kropivnitskaya, D. Majumder, W. Mcbrayer, M. Murray, S. Sanders, R. Stringer, J.D. Tapia Takaki, Q. Wang \cmsinstskip**Kansas State University, Manhattan, USA

** A. Ivanov, K. Kaadze, Y. Maravin, A. Mohammadi, L.K. Saini, N. Skhirtladze, S. Toda \cmsinstskip**Lawrence Livermore National Laboratory, Livermore, USA

** F. Rebassoo, D. Wright \cmsinstskip**University of Maryland, College Park, USA

** C. Anelli, A. Baden, O. Baron, A. Belloni, B. Calvert, S.C. Eno, C. Ferraioli, J.A. Gomez, N.J. Hadley, S. Jabeen, G.Y. Jeng, R.G. Kellogg, J. Kunkle, A.C. Mignerey, F. Ricci-Tam, Y.H. Shin, A. Skuja, M.B. Tonjes, S.C. Tonwar \cmsinstskip**Massachusetts Institute of Technology, Cambridge, USA

** D. Abercrombie, B. Allen, A. Apyan, V. Azzolini, R. Barbieri, A. Baty, R. Bi, K. Bierwagen, S. Brandt, W. Busza, I.A. Cali, M. D’Alfonso, Z. Demiragli, G. Gomez Ceballos, M. Goncharov, D. Hsu, Y. Iiyama, G.M. Innocenti, M. Klute, D. Kovalskyi, K. Krajczar, Y.S. Lai, Y.-J. Lee, A. Levin, P.D. Luckey, B. Maier, A.C. Marini, C. Mcginn, C. Mironov, S. Narayanan, X. Niu, C. Paus, C. Roland, G. Roland, J. Salfeld-Nebgen, G.S.F. Stephans, K. Tatar, D. Velicanu, J. Wang, T.W. Wang, B. Wyslouch \cmsinstskip**University of Minnesota, Minneapolis, USA

** A.C. Benvenuti, R.M. Chatterjee, A. Evans, P. Hansen, S. Kalafut, S.C. Kao, Y. Kubota, Z. Lesko, J. Mans, S. Nourbakhsh, N. Ruckstuhl, R. Rusack, N. Tambe, J. Turkewitz \cmsinstskip**University of Mississippi, Oxford, USA

** J.G. Acosta, S. Oliveros \cmsinstskip**University of Nebraska-Lincoln, Lincoln, USA

** E. Avdeeva, K. Bloom, D.R. Claes, C. Fangmeier, R. Gonzalez Suarez, R. Kamalieddin, I. Kravchenko, A. Malta Rodrigues, J. Monroy, J.E. Siado, G.R. Snow, B. Stieger \cmsinstskip**State University of New York at Buffalo, Buffalo, USA

** M. Alyari, J. Dolen, A. Godshalk, C. Harrington, I. Iashvili, J. Kaisen, D. Nguyen, A. Parker, S. Rappoccio, B. Roozbahani \cmsinstskip**Northeastern University, Boston, USA

** G. Alverson, E. Barberis, A. Hortiangtham, A. Massironi, D.M. Morse, D. Nash, T. Orimoto, R. Teixeira De Lima, D. Trocino, R.-J. Wang, D. Wood \cmsinstskip**Northwestern University, Evanston, USA

** S. Bhattacharya, O. Charaf, K.A. Hahn, A. Kumar, N. Mucia, N. Odell, B. Pollack, M.H. Schmitt, K. Sung, M. Trovato, M. Velasco \cmsinstskip**University of Notre Dame, Notre Dame, USA

** N. Dev, M. Hildreth, K. Hurtado Anampa, C. Jessop, D.J. Karmgard, N. Kellams, K. Lannon, N. Marinelli, F. Meng, C. Mueller, Y. Musienko\cmsAuthorMark35, M. Planer, A. Reinsvold, R. Ruchti, N. Rupprecht, G. Smith, S. Taroni, M. Wayne, M. Wolf, A. Woodard \cmsinstskip**The Ohio State University, Columbus, USA

** J. Alimena, L. Antonelli, B. Bylsma, L.S. Durkin, S. Flowers, B. Francis, A. Hart, C. Hill, R. Hughes, W. Ji, B. Liu, W. Luo, D. Puigh, B.L. Winer, H.W. Wulsin \cmsinstskip**Princeton University, Princeton, USA

** S. Cooperstein, O. Driga, P. Elmer, J. Hardenbrook, P. Hebda, D. Lange, J. Luo, D. Marlow, T. Medvedeva, K. Mei, I. Ojalvo, J. Olsen, C. Palmer, P. Piroué, D. Stickland, A. Svyatkovskiy, C. Tully \cmsinstskip**University of Puerto Rico, Mayaguez, USA

** S. Malik \cmsinstskip**Purdue University, West Lafayette, USA

** A. Barker, V.E. Barnes, S. Folgueras, L. Gutay, M.K. Jha, M. Jones, A.W. Jung, A. Khatiwada, D.H. Miller, N. Neumeister, J.F. Schulte, X. Shi, J. Sun, F. Wang, W. Xie \cmsinstskip**Purdue University Northwest, Hammond, USA

** N. Parashar, J. Stupak \cmsinstskip**Rice University, Houston, USA

** A. Adair, B. Akgun, Z. Chen, K.M. Ecklund, F.J.M. Geurts, M. Guilbaud, W. Li, B. Michlin, M. Northup, B.P. Padley, J. Roberts, J. Rorie, Z. Tu, J. Zabel \cmsinstskip**University of Rochester, Rochester, USA

** B. Betchart, A. Bodek, P. de Barbaro, R. Demina, Y.t. Duh, T. Ferbel, M. Galanti, A. Garcia-Bellido, J. Han, O. Hindrichs, A. Khukhunaishvili, K.H. Lo, P. Tan, M. Verzetti \cmsinstskip**Rutgers, The State University of New Jersey, Piscataway, USA

** A. Agapitos, J.P. Chou, Y. Gershtein, T.A. Gómez Espinosa, E. Halkiadakis, M. Heindl, E. Hughes, S. Kaplan, R. Kunnawalkam Elayavalli, S. Kyriacou, A. Lath, K. Nash, M. Osherson, H. Saka, S. Salur, S. Schnetzer, D. Sheffield, S. Somalwar, R. Stone, S. Thomas, P. Thomassen, M. Walker \cmsinstskip**University of Tennessee, Knoxville, USA

** A.G. Delannoy, M. Foerster, J. Heideman, G. Riley, K. Rose, S. Spanier, K. Thapa \cmsinstskip**Texas A&M University, College Station, USA

** O. Bouhali\cmsAuthorMark70, A. Celik, M. Dalchenko, M. De Mattia, A. Delgado, S. Dildick, R. Eusebi, J. Gilmore, T. Huang, E. Juska, T. Kamon\cmsAuthorMark71, R. Mueller, Y. Pakhotin, R. Patel, A. Perloff, L. Perniè, D. Rathjens, A. Safonov, A. Tatarinov, K.A. Ulmer \cmsinstskip**Texas Tech University, Lubbock, USA

** N. Akchurin, J. Damgov, F. De Guio, C. Dragoiu, P.R. Dudero, J. Faulkner, E. Gurpinar, S. Kunori, K. Lamichhane, S.W. Lee, T. Libeiro, T. Peltola, S. Undleeb, I. Volobouev, Z. Wang \cmsinstskip**Vanderbilt University, Nashville, USA

** S. Greene, A. Gurrola, R. Janjam, W. Johns, C. Maguire, A. Melo, H. Ni, P. Sheldon, S. Tuo, J. Velkovska, Q. Xu \cmsinstskip**University of Virginia, Charlottesville, USA

** M.W. Arenton, P. Barria, B. Cox, J. Goodell, R. Hirosky, A. Ledovskoy, H. Li, C. Neu, T. Sinthuprasith, X. Sun, Y. Wang, E. Wolfe, F. Xia \cmsinstskip**Wayne State University, Detroit, USA

** C. Clarke, R. Harr, P.E. Karchin, J. Sturdy \cmsinstskip**University of Wisconsin - Madison, Madison, WI, USA

** D.A. Belknap, J. Buchanan, C. Caillol, S. Dasu, L. Dodd, S. Duric, B. Gomber, M. Grothe, M. Herndon, A. Hervé, P. Klabbers, A. Lanaro, A. Levine, K. Long, R. Loveless, T. Perry, G.A. Pierro, G. Polese, T. Ruggles, A. Savin, N. Smith, W.H. Smith, D. Taylor, N. Woods \cmsinstskip†: Deceased

1:  Also at Vienna University of Technology, Vienna, Austria

2:  Also at State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China

3:  Also at Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS/IN2P3, Strasbourg, France

4:  Also at Universidade Estadual de Campinas, Campinas, Brazil

5:  Also at Universidade Federal de Pelotas, Pelotas, Brazil

6:  Also at Université Libre de Bruxelles, Bruxelles, Belgium

7:  Also at Deutsches Elektronen-Synchrotron, Hamburg, Germany

8:  Also at Joint Institute for Nuclear Research, Dubna, Russia

9:  Now at Ain Shams University, Cairo, Egypt

10: Now at British University in Egypt, Cairo, Egypt

11: Also at Zewail City of Science and Technology, Zewail, Egypt

12: Also at Université de Haute Alsace, Mulhouse, France

13: Also at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia

14: Also at CERN, European Organization for Nuclear Research, Geneva, Switzerland

15: Also at RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany

16: Also at University of Hamburg, Hamburg, Germany

17: Also at Brandenburg University of Technology, Cottbus, Germany

18: Also at Institute of Nuclear Research ATOMKI, Debrecen, Hungary

19: Also at MTA-ELTE Lendület CMS Particle and Nuclear Physics Group, Eötvös Loránd University, Budapest, Hungary

20: Also at Institute of Physics, University of Debrecen, Debrecen, Hungary

21: Also at Indian Institute of Technology Bhubaneswar, Bhubaneswar, India

22: Also at University of Visva-Bharati, Santiniketan, India

23: Also at Indian Institute of Science Education and Research, Bhopal, India

24: Also at Institute of Physics, Bhubaneswar, India

25: Also at University of Ruhuna, Matara, Sri Lanka

26: Also at Isfahan University of Technology, Isfahan, Iran

27: Also at Yazd University, Yazd, Iran

28: Also at Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran

29: Also at Università degli Studi di Siena, Siena, Italy

30: Also at Purdue University, West Lafayette, USA

31: Also at International Islamic University of Malaysia, Kuala Lumpur, Malaysia

32: Also at Malaysian Nuclear Agency, MOSTI, Kajang, Malaysia

33: Also at Consejo Nacional de Ciencia y Tecnología, Mexico city, Mexico

34: Also at Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

35: Also at Institute for Nuclear Research, Moscow, Russia

36: Now at National Research Nuclear University ’Moscow Engineering Physics Institute’ (MEPhI), Moscow, Russia

37: Also at St. Petersburg State Polytechnical University, St. Petersburg, Russia

38: Also at University of Florida, Gainesville, USA

39: Also at P.N. Lebedev Physical Institute, Moscow, Russia

40: Also at California Institute of Technology, Pasadena, USA

41: Also at Budker Institute of Nuclear Physics, Novosibirsk, Russia

42: Also at Faculty of Physics, University of Belgrade, Belgrade, Serbia

43: Also at INFN Sezione di Roma; Sapienza Università di Roma, Rome, Italy

44: Also at University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia

45: Also at Scuola Normale e Sezione dell’INFN, Pisa, Italy

46: Also at National and Kapodistrian University of Athens, Athens, Greece

47: Also at Riga Technical University, Riga, Latvia

48: Also at Institute for Theoretical and Experimental Physics, Moscow, Russia

49: Also at Albert Einstein Center for Fundamental Physics, Bern, Switzerland

50: Also at Adiyaman University, Adiyaman, Turkey

51: Also at Istanbul Aydin University, Istanbul, Turkey

52: Also at Mersin University, Mersin, Turkey

53: Also at Cag University, Mersin, Turkey

54: Also at Piri Reis University, Istanbul, Turkey

55: Also at Gaziosmanpasa University, Tokat, Turkey

56: Also at Ozyegin University, Istanbul, Turkey

57: Also at Izmir Institute of Technology, Izmir, Turkey

58: Also at Marmara University, Istanbul, Turkey

59: Also at Kafkas University, Kars, Turkey

60: Also at Istanbul Bilgi University, Istanbul, Turkey

61: Also at Yildiz Technical University, Istanbul, Turkey

62: Also at Hacettepe University, Ankara, Turkey

63: Also at Rutherford Appleton Laboratory, Didcot, United Kingdom

64: Also at School of Physics and Astronomy, University of Southampton, Southampton, United Kingdom

65: Also at Instituto de Astrofísica de Canarias, La Laguna, Spain

66: Also at Utah Valley University, Orem, USA

67: Also at Argonne National Laboratory, Argonne, USA

68: Also at Erzincan University, Erzincan, Turkey

69: Also at Mimar Sinan University, Istanbul, Istanbul, Turkey

70: Also at Texas A&M University at Qatar, Doha, Qatar

71: Also at Kyungpook National University, Daegu, Korea