Regular Article - Theoretical Physics

Neutral current forward–backward asymmetry: from to PDF determinations

¹ School of Physics and Astronomy, University of Southampton, Highfield, Southampton, SO17 1BJ, UK
² Particle Physics Department, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, UK
³ Institut für Theoretische Physik, Universität Münster, 48149, Münster, Germany
⁴ Elementaire Deeltjes Fysica, Universiteit Antwerpen, 2020, Antwerpen, Belgium
⁵ Theoretical Physics Department, University of Oxford, Oxford, OX1 3NP, UK

^* e-mail: fiaschi@uni-muenster.de

Received: 28 June 2018
Accepted: 27 July 2018
Published online: 19 August 2018

Abstract

Measurements of the forward–backward asymmetry in neutral-current Drell–Yan di-lepton production have primarily been used for determinations of the weak mixing angle . We observe that, unlike the case of Run-I of the Large Hadron Collider (LHC Run-I), for the first time at the LHC Run-II the reconstructed forward–backward asymmetry has the capability of placing useful constraints on the determination of the parton distribution functions (PDFs). By examining the statistical and the PDF uncertainties on the reconstructed forward–backward asymmetry, we investigate its potential for disentangling the flavour content of quark and antiquark PDFs. Access to the valence/sea u-quark and to the sea up-type antiquark PDFs, in particular, may be gained by the appropriate use of selection cuts in the rapidity of the emerging lepton pair in regions both near the Z-boson peak and away from it, in a manner complementary, though more indirect, to the case of the charged-current asymmetry. We study the extension of these results for the planned high-luminosity (HL) LHC.