$W^+ W^-$ pair production in proton-proton collisions: small missing terms

TL;DR

This paper investigates subleading photon-photon induced processes in $W^+ W^-$ production at proton-proton colliders, revealing their significance at high transverse momenta and invariant masses, which impacts Standard Model tests and new physics searches.

Contribution

It introduces and quantifies previously neglected photon-induced processes, including resolved photons and various elastic-inelastic contributions, in $W^+ W^-$ production calculations.

Findings

Photon-photon processes contribute 1-2% to total cross section.

Their contribution rises to about 10% at high transverse momenta.

Photon-induced processes become comparable to dominant mechanisms at large invariant masses.

Abstract

$W^+ W^-$ production is one of the golden channels for testing the Standard Model as well for searches beyond the Standard Model. We discuss many new subleading processes for inclusive production of $W^+ W^-$ pairs generally not included in the litterature so far. We focus mainly on photon-photon induced processes. We include elastic-elastic, elastic-inelastic, inelastic-elastic and inelastic-inelastic contributions. We also calculate the contributions with resolved photons including the partonic substructure of the virtual photon. Predictions for the total cross section and differential distributions in $W$- boson rapidity and transverse momentum as well as $WW$ invariant mass are presented. The $\gamma \gamma$ components only constitute about 1-2 \% of the inclusive $W^+ W^-$ cross section but increases up to about 10 \% at large $W^{\pm}$ transverse momenta, and are even comparable to the dominant $q \bar q$ component at large $M_{WW}$, i.e. are much larger than the $g g \to W^+ W^-$ one.