Abstract
We shall describe the physics program with tagged forward protons, focusing on Central Exclusive Production in polarized proton-proton collisions at the Relativistic Heavy Ion Collider (RHIC), with the STAR detector at √ s = 200 GeV. Preliminary results in CEP of two oppositely charged pions and kaons produced in the processes pp → ppπ + π − and pp → ppK + K − shall be presented. Those Double Pomeron Exchange (DPE) processes, allow the final states to be dominated by gluonic exchanges. Silicon strip detectors placed in Roman Pots were used for measuring forward protons. The preliminary results are based on the measurement of the recoil system of charged particles in the STAR experiment’s Time Projection Chamber (TPC). Ionization energy loss, dE/dx, of charged particles was used for particle identification (PID).
Highlights
Diffractive processes at high energies occur mostly via the exchange of a color singlet object with internal quantum numbers of the vacuum [1]
This process belongs to a class of Double Pomeron Exchange (DPE) processes and is commonly called a Central Production process
The case when all the products of the interaction are measured and the balance of momentum for all the products of the reaction is satisfied in the reaction, including forward protons, is called Central Exclusive Production (CEP) process
Summary
Diffractive processes at high energies occur mostly via the exchange of a color singlet object (the “Pomeron”) with internal quantum numbers of the vacuum [1]. One of the diffractive processes of interest is shown, a process with tagged forward protons pp → pMX p, in which two protons emerge intact after the scattering and a recoil system MX is produced mostly around pseudorapidity η ≈ 0 (midrapidity) This process belongs to a class of Double Pomeron Exchange (DPE) processes and is commonly called a Central Production process. Triggering on forward protons at high energies in this central production process allows selection of interactions for which gluonic exchanges are dominant. Because of the constraints provided by the double Pomeron interaction, the glueballs, and other states coupling preferentially to gluons, are expected to be produced with much reduced backgrounds compared to standard hadronic production processes [7]. The experiments at CERN ISR Collider [9,10,11] and CERN SPS [12, 13] have provided measurements of many CEP-type processes, their interpretation in terms of Pomeron-Pomeron interactions is not fully justified [14] at these rather low center-of-mass energies (62 GeV for ISR and 30 GeV for SPS)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
