Features of W production in p-p, p-Pb and Pb-Pb collisions

TL;DR

This paper analyzes W boson production across various high-energy hadronic collisions, highlighting scaling laws, charge asymmetry, and proposing precision measurements at the LHC to improve understanding of parton distributions.

Contribution

It introduces a simple scaling law for lepton charge asymmetry in different collision systems and compares predictions with existing data, suggesting new precision observables for LHC experiments.

Findings

Good agreement between predictions and existing data

Scaling law for lepton charge asymmetry holds across systems

Proposes new precision observables for LHC

Abstract

We consider the production of inclusive W bosons in variety of high-energy hadronic collisions: p--p, p--$\overline{\rm p}$, p--Pb, and Pb--Pb. In particular, we focus on the resulting distributions of charged leptons from W decay that can be measured with relatively low backgrounds. The leading-order expressions within the collinearly factorized QCD indicate that the center-of-mass energy dependence at forward/backward rapidities should be well approximated by a simple power law. The scaling exponent is related to the small-$x$ behaviour of the quark distributions, which is largely driven by the parton evolution. An interesting consequence is the simple scaling law for the lepton charge asymmetry which relates measurements in different collision systems. The expectations are contrasted with the existing data and a very good overall agreement is found. Finally, we propose precision observables to be measured at the LHC.