Using Drell-Yan $A_{FB}$ to constrain PDFs

Abstract

We show that measurements of the forward-backward charge asymmetry ($A_{FB}(M,y)$) of Drell-Yan dilepton events produced at hadron colliders provide a new powerful tool to constrain Parton Distribution Functions (PDFs). PDF uncertainties are the dominant source of systematic error in precision measurements at hadron colliders (e.g. ${\chi }^2$ values of fits to extract ${\sin }^2{\theta }_{eff}^{lept}(M_Z)$ from $A_{FB}(M,y)$ with different PDF replicas can be used to place additional constraints on PDFs.In turn, using these constrained PDFs significantly reduces the PDF errors in precision measurements of electroweak parameters. The measurement of the on-shell ${\sin }^2{\theta }_W=1-M_W^2/M_Z^2$ is equivalent to an indirect measurement of the W mass. The errors in this indirect measurement of the W mass are competitive with direct measurements. For example, with 200 fb${}^{-1}$ at 13 TeV, the expected error in the indirect measurement of the W mass is $\pm$9 MeV.

arXiv comment6 pages, 2 Figures. Presented by A. Bodek at The XXIII International Workshop on Deep Inelastic Scattering and Related Subjects April 27 - May 1, 2015 Southern Methodist University, Dallas, Texas 75275, To be published in Proceedings

References in corpus (6)

• Reweighting NNPDFs: the W lepton asymmetry
• Implications of Hadron Collider Observables on Parton Distribution Function Uncertainties
• PDF reweighting in the Hessian matrix approach
• Bayesian Reweighting for Global Fits
• Measurement of the effective weak mixing angle in $p\bar{p}\to Z/{\gamma }^{\ast }\to e^{+}{e}^{-}$ events
• Indirect measurement of $si{n}^2{\theta }_W$ (M_W) using e+e- pairs in the Z-boson region with $p\bar{p}$ collisions at a center-of-momentum energy of 1.96 TeV