The role of finite-size effects on the spectrum of equivalent photons in proton–proton collisions at the LHC

Abstract

When computing such cross sections, it has already been shown that finite size effects of colliding protons are important to consider for a realistic estimate of the cross sections. These first results have been essential in understanding the physics case of heavy-ion collisions in the low invariant mass range, where heavy ions collide to form an exclusive final state like a J /Ψ vector meson. In this paper, our purpose is to present some calculations that are valid also for the exclusive production of high masses final states in proton-proton collisions, like the production of a pair of W bosons or the Higgs boson. Therefore, we propose a complete treatment of the finite size effects of incident protons irrespective of the mass range explored in the collision. Our expectations are shown to be in very good agreement with existing experimental data obtained at the LHC.

Exclusive physics at the LHC with SuperChic 2

“…This omits entirely any process-dependence in the survival factor and will not give a reliable estimate for the expected suppression. After an explicit calculation, we find that including only the b t dependence of the photon flux, as in [77], tends to underestimate the survival factor by ∼10-20 % for lepton pair production within the ATLAS event selection. It should be emphasised that this does not correspond to a genuine model dependence: the correct inclusion of the photon q ⊥ dependence as discussed in Sect.…”

“…In the recent work of [75] for example, where the question of constraining the photon PDF in exclusive l + l − and W + W − production is considered, soft survival effects, which as noted above may be particularly important if proton dissociative events are included, are omitted. 3 Another important example of this is in [77], where an evaluation of the survival factor for two-photon induced processes is given, the predictions of which are compared to in the ATLAS data in [74]. While a differential treatment of the survival factor is given, and for example the same qualitative decrease with M X as in Fig.…”

Light-by-light scattering with intact protons at the LHC: from standard model to new physics

“…In our studies, we assumed a survival probability of about 90%. More recent studies [25] show that this might be slightly optimistic and the survival probability at high di-photon masses might be of the order of 60%. In that case, the yield should be reduced accordingly.…”

Photon-initiated production of a dilepton final state at the LHC: Cross section versus forward-backward asymmetry studies

“…Recently, it has been analysed in the context of Higgs boson measurements. In particular, it has been computed for the four-lepton final state as a background to the Higgs production where the Higgs boson decays into a Z-boson pair giving rise ultimately to four leptons in the final state [17]. The PI contribution has been also calculated for two-leptons and two-bosons final states [18][19][20][21][22][23][24][25][26].…”