Recent results on Central Exclusive Production with the STAR detector

TL;DR

This paper reports measurements of central exclusive production of charged particle pairs in proton-proton collisions at RHIC, comparing results at 200 GeV and 510 GeV, and testing phenomenological models of Double Pomeron Exchange.

Contribution

It provides new differential cross section measurements for exclusive hadron pair production at two collision energies, with detailed comparison to theoretical models.

Findings

Cross sections measured as functions of relevant observables.

Results show similar features at 200 GeV and 510 GeV.

Data agree with phenomenological DPE models.

Abstract

We present results on the Central Exclusive Production of charged particle pairs $h^{+}h^{-}$ ($h = \pi, K, p$), $pp\to p^\prime+h^{+}h^{-}+p^\prime$, obtained with the STAR experiment at RHIC in proton-proton collisions at a center-of-mass energy of $\sqrt{s} = 200$ GeV. All final-state particles were reconstructed, including forward-scattered protons detected in the Roman Pot system. As a result, the Double Pomeron Exchange (DPE) events were selected and the non-exclusive backgrounds were efficiently rejected. Differential fiducial cross sections were measured as functions of observables related to the central hadronic final state and to the forward-scattered protons. The measured cross sections were compared to phenomenological model predictions based on the DPE. We also present preliminary results on the measurement of the same physics process at higher collision energy $\sqrt{s} = 510$ GeV. The data demonstrate features similar to those observed at $\sqrt{s} = 200$ GeV.