Direct measurement of the W production charge asymmetry in pp collisions at square root s=1.96 TeV

Phys Rev Lett. 2009 May 8;102(18):181801. doi: 10.1103/PhysRevLett.102.181801. Epub 2009 May 6.

Abstract

We present the first direct measurement of the W production charge asymmetry as a function of the W boson rapidity yW in pp collisions at sqrt[s]=1.96 TeV. We use a sample of W-->enu events in data from 1 fb-1 of integrated luminosity collected using the CDF II detector. In the region |yW|<3.0, this measurement is capable of constraining the ratio of up- and down-quark momentum distributions in the proton more directly than in previous measurements of the asymmetry that are functions of the charged-lepton pseudorapidity.