Rapidity correlations inWγ production at hadron colliders

We study the correlation of photon and charged lepton pseudorapidities, η(γ) and η(l), l=e,μ, in ${\mathit{pp}}^{\left(\mathrm{-}\right)}$→${\mathit{W}}^{\pm }$γ+X→${\mathit{l}}^{\pm }$p${\mathrm{/}}_{\mathit{T}}$γ+X. In the standard model, the Δη(γ,l)=η(γ)-η(l) differential cross section is found to exhibit a pronounced dip at Δη(γ,l)≊∓0.3 (=0) in pp¯(pp) collisions, which originates from the radiation zero present in qq¯’→Wγ. The sensitivity of the Δη(γ,l) distribution to higher order QCD corrections, nonstandard WWγ couplings, the W+ jet ‘‘fake’’ background, and the cuts imposed is explored. At hadron supercolliders, next-to-leading order QCD corrections are found to considerably obscure the radiation zero. The advantages of the Δη(γ,l) distribution over other quantities which are sensitive to the radiation zero are discussed. We conclude that photon-lepton rapidity correlations at the Fermilab Tevatron offer a unique opportunity to search for the standard model radiation zero in hadronic Wγ production.