From Elastic Scattering to Central Exclusive Production: Physics with Forward Protons at RHIC

TL;DR

This paper discusses the RHIC physics program involving forward protons, highlighting the transition from elastic scattering studies to exploring inelastic channels like Central Exclusive Production, with results from PP2PP and STAR experiments.

Contribution

It introduces an expanded physics program at RHIC that combines elastic and inelastic channels using forward proton detection, integrating PP2PP and STAR experiments.

Findings

Results from elastic scattering measurements at RHIC.

Evidence for non-elastic channels like CEP and SD.

Integration of forward proton detection into STAR operations.

Abstract

We describe a physics program at the Relativistic Heavy Ion Collider (RHIC) with tagged forward protons. The program started with the proton-proton elastic scattering experiment (PP2PP), for which a set of Roman Pot stations was build. The PP2PP experiment took data at RHIC as a dedicated experiment at the beginning of RHIC operations. To expand the physics program to include non-elastic channels with forward protons, like Central Exclusive Production (CEP), Central Production (CP) and Single Diffraction Dissociation (SD), the experiment with its equipment was merged with the STAR experiment at RHIC. Consequently the expanded program, which included both elastic and inelastic channels became part of the physics program and operations of the STAR experiment. In this paper we shall describe the physics results obtained by the PP2PP and STAR experiments to date.