Determination of the strange quark density of the proton from ATLAS measurements of the W->l nu and Z->ll cross sections

TL;DR

This paper presents a QCD analysis combining ATLAS and HERA data to determine the strange quark density in the proton, revealing a symmetric light quark sea at low x and quantifying the strange-to-down quark ratio.

Contribution

It provides the first direct determination of the strange quark density in the proton using LHC and HERA data, highlighting the symmetry of the light quark sea at low x.

Findings

Strange-to-down sea quark ratio is approximately 1.00 with uncertainties.

ATLAS data supports a symmetric light quark sea at low x.

The analysis constrains the strange quark distribution at Q^2 = 1.9 GeV^2.

Abstract

A QCD analysis is reported of ATLAS data on inclusive W and Z boson production in pp collisions at the LHC, jointly with ep deep inelastic scattering data from HERA. The ATLAS data exhibit sensitivity to the light quark sea composition and magnitude at Bjorken x ~ 0.01. Specifically, the data support the hypothesis of a symmetric composition of the light quark sea at low x. The ratio of the strange-to-down sea quark distributions is determined to be 1.00(+0.25-0.28) at absolute four-momentum transfer squared Q^2 = 1.9 GeV^2 and x = 0.023.