Parton Distributions and the LHC: W and Z Production

Abstract

W and Z bosons will be produced copiously at the LHC proton-proton collider. We study the parton distribution dependence of the total production cross sections and rapidity distributions, paying particular attention to the uncertainties arising from uncertainties in the parton distributions themselves. Variations in the gluon, the strong coupling, the sea quarks and the overall normalisation are shown to lead to small but non-negligible variations in the cross section predictions. Ultimately, therefore, the measurement of these cross sections will provide a powerful cross check on our knowledge of parton distributions and their evolution.

Figures (17)

• Figure 1: Values of $x$ and $Q^2$ probed in the production of an object of mass $M$ and rapidity $y$ at the LHC, $\sqrt{s} = 14\; {\rm TeV}$.
• Figure 2: Comparison of the MRST(${q\uparrow}$) and default MRST pdfs at $Q^2 = 10$ and 10$^4$ GeV$^2$.
• Figure 3: Comparison of the MRST(${q\downarrow}$) and default MRST pdfs at $Q^2 = 10$ and 10$^4$ GeV$^2$.
• Figure 4: Comparison of the strange sea from the NLO analysis of CCFR CCFRMM dimuon production with the default MRST (solid line) and a variation of $\pm 10\%$ in the proportion (strange sea)/(total sea) at $Q_0^2 = 1$ GeV$^2$ representing the input to the pdf sets MRST(${s\uparrow}$) and MRST(${s\downarrow}$).
• Figure 5: Parton decomposition of the $W^+$ (solid line) and $W^-$ (dashed line) total cross sections in $p \bar{p}$ and $pp$ collisions. Individual contributions are shown as a percentage of the total cross section in each case. In $p \bar{p}$ collisions the decomposition is the same for $W^+$ and $W^-$.