The Charge Asymmetry in W-Boson Decays Produced in p-pbar Collisions at sqrt(s) = 1.8 TeV

TL;DR

The [ital W] asymmetry data provide stronger constraints on [ital d]/[ital u] ratio than the recent measurements of [ital F][sub 2][sup [mu][ital n], which are limited by uncertainties originating from deuteron corrections.

Abstract

The charge asymmetry has been measured using $19,039~W$ decays recorded by the CDF detector during the 1992-93 run of the Tevatron Collider. The asymmetry is sensitive to the ratio of $d$ and $u$ quark distributions to $x<0.01$ at $Q^2 \approx M_W^2$, where nonperturbative effects are minimal. It is found that of the two current sets of parton distributions, those of Martin, Roberts and Stirling (MRS) are favored over the sets most recently produced by the CTEQ collaboration. The $W$ asymmetry data provide a stronger constraints on $d/u$ ratio than the recent measurements of $F_2^{μn}/F_2^{μp}$ which are limited by uncertainties originating from deutron corrections.

Figures (3)

• Figure 1: The charge asymmetry before applying any corrections found in each of the detector types (Central EM, Plug EM and Central Muon). Also shown (dashed line) is the effect of allowing the $W$ couplings to go to their 90% C.L. limits.
• Figure 2: The fully corrected charge asymmetry after the data from the various detectors are combined and folded about $y=0$. The error bars along the x-axis show the total systematic errors associated with each bin.
• Figure 3: (a) The $d/u$ ratios for various parton distributions. (b) The $d/u$ ratios of various PDFs after they have been shifted to agree with MRS D$_0^{\prime}$ at x=0.2; those which have the largest average slope predict the largest asymmetry.