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

TL;DR

This paper predicts proton-antiproton pair production in ultraperipheral heavy-ion collisions at the LHC, using a detailed model fitted to Belle data, and provides cross sections and distributions relevant for experimental studies.

Contribution

It introduces a comprehensive model for $par{p}$ production in UPC, incorporating multiple exchange mechanisms and fitting to Belle data, to predict cross sections at LHC energies.

Findings

Total cross sections range from 100 to 500 μb depending on experimental cuts.

The model successfully describes Belle data for $ o p ar{p}$ reactions.

Predicted distributions can guide future LHC measurements.

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) $^{208}\!Pb \, ^{208}\!Pb \to$ $^{208}\!Pb \, ^{208}\!Pb \,p \bar{p}$. 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.