Production of $p\bar{p}$ pairs in UPC at the LHC

Abstract

We discuss production of $p\bar{p}$ pairs in two-photon interactions in heavy-ion collisions. We present predictions for the ultraperipheral, ultrarelativistic, heavy-ion collisions (UPC) ${}^{208}Pb{}^{208}Pb\to$ ${}^{208}Pb{}^{208}Pbp\bar{p}$. The parameters of vertex form factors are adjusted to the Belle data for the $\gamma \gamma \to p\bar{p}$ reaction. To described the Belle data we include the proton-exchange, the $f_2(1270)$ and $f_2(1950)$ $s$-channel exchanges, as well as the hand-bag mechanism. Then, the total cross section and several differential distributions for experimental cuts corresponding to the LHC experiments are presented. The distribution in ${\mathrm{y}}_{diff}$, the rapidity distance between the proton and antiproton, is particularly interesting. We find the total cross sections: 100 $\mu$b for the ALICE cuts, 160 $\mu$b for the ATLAS cuts, 500 $\mu$b for the CMS cuts, and 104 $\mu$b taking into account the LHCb cuts. This opens a possibility to study the $\gamma \gamma \to p\bar{p}$ process in UPC at the LHC.

Comments: 6 pages, 3 figures, presented by P. Lebiedowicz at the XIII Workshop on Particle Correlations and Femtoscopy, 22-26 May 2018, Kraków, Poland