Subleading processes in production of $W^+ W^-$ pairs in proton-proton collisions

Abstract

We discuss many new subleading processes for inclusive production of W + W pairs not included in the literature so far. We focus on photon-photon induced processes. We include elastic-elastic, elastic-inelastic, inelastic-elastic and inelastic-inelastic contributions. The inelastic photon distributions in the proton are calculated in two different ways: naive approach used already in the literature and using photon distributions by solving special evolution equation with photon being a parton in the proton. The results strongly depend on the approach used. We calculate also contributions with resolved photons. The diffractive components have similar characteristics as the photon-photon elastic-inelastic and inelastic-elastic mechanisms. The subleading contributions are compared with the well known q¯ q and gg as well as with double-parton scattering contributions. 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 components constitute only about 1-2 % of the inclusive W + W cross section but about 10 % at large W ± transverse momenta, and are even comparable to the dominant q¯ q component at large MWW, i.e. are much larger than the often celebrated gg → W + W component. Its size is comparable to double parton scattering contribution. Only elastic-elastic, elastic-inelastic and inelastic-elastic contributions could be potentially measured to verify our predictions using forward proton detectors.