Combination and Standar Model Scalar Boson Properties in CMS

TL;DR

This paper presents combined results from CMS on the properties of the Higgs boson, confirming its consistency with the Standard Model and testing various spin-parity hypotheses with extensive data.

Contribution

First combined analysis of CMS data confirming the Higgs boson properties align with the Standard Model predictions and testing alternative spin-parity hypotheses.

Findings

Significance of 6.9 sigma for the boson

Measured mass of 125.8 GeV with uncertainties

No significant deviations from the SM Higgs couplings

Abstract

Combination results of the recently discovered boson are presented using data samples corresponding to integrated luminosities of up to 5.1 $\invfb$ at 7 TeV and up to 12.2 $\invfb$ at 8 TeV of proton-proton collisions collected with CMS experiment at LHC. The significance of the new boson is 6.9 $\sigma$ with mass measured to be 125.8 $\pm$ 0.4 (stat) $\pm$ 0.4 (syst). The event yields obtained by the different analyses targeting specific decay modes and production mechanisms are consistent with those predicted for the stand model (SM) Higgs boson. The best-fit signal strength for all channels combined, expressed in units of the SM Higgs boson cross section, is 0.88 $\pm$ 0.21 at the measured mass. The consistency of the couplins of the observed boson with those expected for the SM Higgs boson is tested in various ways, and no significant deviations are found. Results on the test of different spin-parity hypotheses of the observed boson are also shown, but with updated data samples corresponding to integrated luminosities of 5.1 $\invfb$ at 7 TeV and 19.6 $\invfb$ at 8 TeV in two channels H $\rightarrow$ WW $\rightarrow~2\ell2\nu$ and H $\rightarrow$ ZZ $\rightarrow~4\ell$ separately. Under the assumption that the observed boson has spin 0 and positive parity, the pure scalar hypothesis is found to be consistent with the observed boson when compared to other tested spin-parity hypotheses. The data in the H $\rightarrow$ ZZ $\rightarrow~4\ell$ channel disfavor the pseudo-scalar hypothesis $0^-$ with a CLs value of 0.16$%$, disfavor the pure spin-2 hypothesis of a narrow resonance with the minimal couplings to the vector bosons with a CLs value of 1.5$%$, and disfavor the pure spin-1 hypothesis with even smaller CLs value.