Rapidity Correlations in $Wγ$ Production at the Tevatron

Abstract

We study the correlation of photon and charged lepton pseudorapidities, $η(γ)$ and $η(\ell)$, $\ell=e,\,μ$, in $p\bar p\rightarrow W^\pmγ+X\rightarrow \ell^\pm p\llap/_Tγ+X$ at the Tevatron. In the Standard Model, the $Δη(γ,\ell)= η(γ) - η(\ell)$ differential cross section is found to exhibit a pronounced dip at $Δη(γ,\ell) \approx \mp 0.4$, which originates from the radiation zero present in $q\bar q'\rightarrow Wγ$. The sensitivity of the $Δη(γ,\ell)$ distribution to higher order QCD corrections, non-standard $WWγ$ couplings, and the cuts imposed is explored. The $Δη(γ,\ell)$ distribution is compared with other quantities which are sensitive to the radiation zero.