Measurements of vector-boson production in AT- LAS and CMS

Abstract

Vector-boson production in p i p collisions in LHC Run-1 has been extensively studied by ATLAS and CMS. Charged and neutral-current Drell-Yan cross sections are sensitive to the parton distribution functions of the proton and electroweak corrections. The measurements of the neutral-current Drell-Yan process in three distinct kinematic regions, i.e. at the Z boson mass peak, below, and above, are performed. The results are compared to NLO Monte Carlo simulations and to NNLO QCD predictions corrected for NLO EW effects calculated using various parameterisations of the parton distribution functions. An overview of these results is given. The proton-proton collisions at the Large Hadron Collider (LHC) are in fact parton-parton collisions, where the momentum fraction x carried by a parton can be described in terms of Parton Distribution Functions (PDFs). These colliding partons may undergo a hard-scattering process producing, for example, a Z boson in the final state. The production cross section for such a process may be factorised into the hard scattering between the partons and the PDF of each of the interacting partons. Via this hard scatter, one can test perturbative QCD (pQCD). Predictions for such processes are available at next-to-next-to-leading order (NNLO). Drell-Yan (DY) production at the LHC probes the structure of the PDFs over a wide range of x and four-momentum transfer Q 2 . The quark and gluon PDFs may be parameterised by functions that describe their shapes as a function of x. One can then use such processes to feed information into global QCD fits to extract these PDFs. The cross-section measurements available at the LHC have differing sensitivity to the proton’s PDFs and so much may be gained by including, for example, electroweak boson production as such processes are sensitive to both the valence and sea quark distributions. The recent measurements presented at this PANIC Conference included the transverse momentum p ll and invariant mass mll dependence of the production of Z/γ ¤ ! ll, where the lepton can be either an electron or a muon, as well as the charge asymmetry of W ± production. The results from QCD analyses extracting PDF information were also discussed. A subset of this presentation is summarised in these proceedings.