Abstract
We discuss photon-photon fusion mechanisms of dilepton production in proton-proton collisions with rapidity gap in the main detector and one forward proton in the forward proton detectors. This is relevant for the LHC measurements by ATLAS+AFP and CMS+PPS. Transverse momenta of the intermediate photons are taken into account and photon fluxes are expressed in terms of proton electromagnetic form factors and structure functions. Differential distributions in $\xi_{1/2}$, $M_{ll}$, $Y_{ll}$, $p_{t,ll}$, $M_R$ %pamietac wyjasnic M_R w tekscie are shown and the competition of different mechanisms is discussed. Both double-elastic and single-dissociative processes are included in the analysis. Different parametrizations of the structure functions are used. We discuss also mechanism with one forward $\Delta^+$ isobar, or other proton resonances in the final state. The role of several cuts is studied. We also use SuperChic generator and compare corresponding results to the results of our codes. The soft rapidity gap survival factor is calculated for each contribution separately. The gap survival factor for the single-dissociative mechanism due to minijet emission into the main detector is calculated in addition. It depends on the type of contribution (fully elastic, single dissociation, double dissociation). The soft rapidity gap survival factor for the case of single proton measurement is significantly smaller than that for the inclusive case (no proton measurement). We find only weak dependence on the invariant mass of the dilepton system as well as the lepton pair transverse momentum and sizeable dependence on the pair rapidity. The latter effect is rather difficult to identify experimentally.
Highlights
The production of dilepton pairs via photon-photon fusion was studied both experimentally [1,2] and theoretically [3,4].In [4] we proposed how to include transverse momenta of fusing virtual photons
We discuss photon-photon fusion mechanisms of dilepton production in proton-proton collisions with rapidity gap in the main detector and one forward proton in the forward proton detectors. This is relevant for the LHC measurements by ATLAS þ AFP and CMS þ PPS
In the present paper we have discussed dilepton production via photon-photon fusion with one forward proton, which can be measured in forward detectors such as the AFP for the ATLAS experiment
Summary
The production of dilepton pairs via photon-photon fusion was studied both experimentally [1,2] and theoretically [3,4]. The same processes and a similar formalism were implemented in the recent version of the SUPERCHIC 4 generator [11] This code generates events with four momenta of outgoing particles (leptons, protons, jets). In the present study we shall use the SUPERCHIC 4 code for comparison and in order to estimate the soft rapidity gap survival probability. It is the aim of this paper to investigate what is the influence of the measurement of one proton (limited longitudinal fraction of the outgoing proton) on different leptonic differential distributions, those measured by the ATLAS collaboration. We shall try to include all processes in the state-of-art approach taking into account transverse momenta of intermediate photons
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
