Measurement of the double-differential high-mass Drell-Yan cross section in pp collisions at $\sqrt{s}$ = 8 TeV with the ATLAS detector

TL;DR

This paper reports a precise measurement of the double-differential Drell-Yan cross section at 8 TeV using ATLAS data, providing insights to improve parton distribution functions, especially the photon PDF.

Contribution

It presents the first high-precision double-differential measurement of the Drell-Yan process at high invariant masses, enhancing constraints on parton distribution functions.

Findings

Achieved better than 1% experimental precision at low invariant mass.

Data significantly constrains the photon parton distribution function.

Results agree with NNLO QCD predictions, supporting current theoretical models.

Abstract

This paper presents a measurement of the double-differential cross section for the Drell-Yan $Z/\gamma^{*} \rightarrow \ell^{+} \ell^{-}$ and photon-induced $\gamma\gamma \rightarrow \ell^{+} \ell^{-}$ processes where $\ell$ is an electron or muon. The measurement is performed for invariant masses of the lepton pairs, $m_{\ell\ell}$, between 116 GeV and 1500 GeV, using a sample of 20.3 fb$^{-1}$ of pp collisions data at centre-of-mass energy of $\sqrt{s}$ = 8 TeV collected by the ATLAS detector at the LHC in 2012. The data are presented double differentially in invariant mass and absolute dilepton rapidity as well as in invariant mass and absolute pseudorapidity separation of the lepton pair. The single-differential cross section as a function of $m_{\ell\ell}$ is also reported. The electron and muon channel measurements are combined and a total experimental precision of better than 1% is achieved at low $m_{\ell\ell}$. A comparison to next-to-next-to-leading order perturbative QCD predictions using several recent parton distribution functions and including next-to-leading order electroweak effects indicates the potential of the data to constrain parton distribution functions. In particular, a large impact of the data on the photon PDF is demonstrated.