Study of Central Exclusive Production of $\pi^+\pi^-$, $K^+K^-$ and $p \bar{p}$ Pairs in Proton-Proton Collisions at $\sqrt{s} = 510$ GeV

PAs:    Tomas Truhlar, Wlodek Guryn, Michal Vranovsky, Jaroslav Bielcik
   Tomas.Truhlar@fjfi.cvut.cz, guryn@bnl.gov, vranomic@fjfi.cvut.cz, jaroslav.bielcik@fjfi.cvut.cz

Target journal: Journal of High Energy Physics (JHEP)

Abstract

We report on the measurement of the $pp \ \rightarrow \ p h^+ h^- p$ ($h = \pi, K, p$) central exclusive production process in proton-proton collisions at the center-of-mass energy $\sqrt{\mathrm{s}} = 510$ GeV with the STAR detector at RHIC. At this energy, the process is dominated by a double Pomeron exchange mechanism. The oppositely charged hadron pairs are measured within the central detector of STAR, the Time Projection Chamber, and the Time of Flight. The pairs are identified using the ionization energy loss and the time of flight method. Additionally, the diffractively scattered protons, which remain intact inside the RHIC beam pipe after the collision, are measured in the Roman Pots system allowing for full control of the interaction's kinematics and verification of its exclusivity. Differential cross sections are measured as functions of the azimuthal angle between the outgoing protons and two-hadron invariant mass. These measurements are conducted within a fiducial region defined by the STAR detector’s acceptance, determined based on the central particles’ transverse momenta, pseudorapidities, and the forward-scattered protons’ momenta.