Abstract
Non-perturbative QCD effects from Parton Distribution Functions (PDFs) may be constrained by using high-statistics Large Hadron Collider (LHC) data. Drell-Yan (DY) measurements in the Charged Current (CC) case provide one of the primary means to do this, in the form of the lepton charge asymmetry. We investigate here the impact of measurements in Neutral Current (NC) DY data mapped onto the Forward-Backward Asymmetry (AFB) on PDF determinations, by using the open source fit platform xFitter. We demonstrate the potential impact of AFB data on PDF determinations and perform a thorough analysis of related uncertainties.
Highlights
Non-perturbative QCD effects from Parton Distribution Functions (PDFs) may be constrained by using high-statistics Large Hadron Collider (LHC) data
We conclude this section by noting that, following the observation made in refs. [10, 11], in which detailed comparisons were made between statistical errors and PDF errors for various scenarios with different selection cuts and luminosities, in this paper we have obtained for the first time quantitative results for the reduction of PDF uncertainties from using the AFB asymmetry, and we have identified the charge-weighted sum of u-valence and d-valence PDFs as the distribution which is most sensitive to AFB
High-statistics measurements from the LHC Runs 2, 3 and the HL-LHC stage can be exploited to place constraints on the PDFs
Summary
We describe the implementation of the AFB observable in xFitter [24], the generation of the pseudodata and the fitting procedure. In order to obtain estimates as close as possible to the projected experimental accuracy, we have computed the number of events by convoluting the LO cross section without any acceptance cut with an acceptance times efficiency factor with typical value ∼20% corresponding to realistic detector response [35], and with a mass dependent k-factor reproducing the NNLO QCD corrections [36, 37]. We stress that the latter is used in the evaluation of the number of events in eq (2.1), not in the evaluation of the observable itself. With the goal of an exhaustive analysis over several PDF sets, multiple datafiles have been generated adopting the recent CT14nnlo [3], NNPDF3.1nnlo (Hessian set) [4], ABMP16nnlo [5], HERAPDF2.0nnlo (EIG) [7] and MMHT2014nnlo [6] PDF sets
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