Speaker
Description
We discuss 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 LHC measurements by ATLAS+AFP and CMS+PPS. Transverse momenta of the intermediate photons are included and photon fluxes are expressed in terms of proton electromagnetic form factors and structure functions. Differential distributions in $\xi_{1/2}$, $M_{ll}$, $Y_{ll}$, $p_{t,ll}$ are shown and the competition of different mechanisms is discussed. Both double-elastic and single-dissociative processes are included in the calculation. We discuss also mechanism with one forward $\Delta^+$ isobar, or other proton resonances in the final state not discussed so far in the literature. The role of several cuts is studied. The rapidity gap survival factor is calculated for each contribution separately. 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). The gap survival with and without proton measurement in forward proton detector are compared and the underlying dynamics is discussed. The dependence on the parametrization of the proton structure functions is shown in addition. The gap survival factor for the single-dissociative mechanism due to minijet emission into the main detector are calculated in addition. The corresponding gap survival factor depends on the invariant mass of the dilepton system as well as the mass of the proton remnant and rapidity of the lepton pair.
A. Szczurek, B. Linek and M. {\L}uszczak, a paper in preparation.
| antoni.szczurek@ifj.edu.pl |
