Measurement of the Drell{Yan triple-differential cross-section in pp collisions at ps = 8 TeV with the ATLAS detector

Abstract

This thesis presents the measurement and results of the Z= ! + �� Drell{Yan tripledi erential cross-section, using 20:24 fb��1of ATLAS data recorded in 2012 at a centre-of-mass energy of ps = 8TeV. The triple-differential cross-section is measured as a function of dimuon invariant mass, m , dimuon rapidity, y , and lepton decay angle in the Collins-Soper frame, cos . These dimensions provide sensitivity to the parton composition of the proton through the parton density functions, PDFs, and the weak e ective mixing angle, sin2 e : W , via the forward-backward asymmetry, AFB. The measurement is performed on and around the Z-boson's invariant mass peak, 46 < m < 200 GeV, in a kinematic ducial volume of muon transverse momentum, pT > 20 GeV, and muon pseudo-rapidity j j 2:4. The results are unfolded from the detector level to the Born, bare and dressed levels, where a precision of < 0:6% is reported in the central bins. The data is combined with an electron channel measurement resulting in a combined result with reduced total uncertainty. The combined result is shown to constrain PDF uncertainties and achieve the most constrained sin2 e : W uncertainty yet reported at the LHC.