Central Exclusive Production in Proton-Proton Collisions with the STAR Experiment at RHIC

Abstract

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).

Decays of the f0(1370) scalar glueball candidate in pp Central Exclusive Production (CEP) and in antiproton annihilations at rest

“…Fig. 3 [23][24][25] shows row data of π + πpairs in pp CEP data at √𝑠=200 GeV produced by the STAR experiment at RICH in a 2015 run with β*=0.85 m setting of the storage rings and the two sets of roman pots positioned at the two sides of the central detector at 15.8 and 17.6 m distance. This second configuration of the machine and forward detectors gives access to the kinematical region with four momentum transfer square lt1l and lt2l at both proton vertices in the window 0.03 ˂ lt1l , lt2l ˂ 0.3 GeV 2 (also shown in fig.…”

“…An isolated π + πpeak practically without background and well separated from the f0(980) signal by a valley nearly devoid of events present in pp CEP data of the STAR experiment [18] has been interpreted as a clear manifestation of the f0(1370) meson as an isolated structure [19,20]. This interpretation is based on STAR data [18,[21][22][23][24][25], on the scaling laws of CEP [8,26] and on results of the AFS experiment [27,28] at the CERN ISR. This points are discussed in section 2.…”

“…Kinematical acceptances in the lt1l, lt2l plane of the AFS[27,28] and STAR[18,23] pp CEP experimentsFig. 3. π + πmass plot of STAR pp CEP raw data of the 200 GeV 2012 run with 0.03 ˂lt1l, lt2l˂0.3 GeV 2 kinematic coverage of both scattered protons (Fig.…”

“…Fig.2. Kinematical acceptances in the lt1l, lt2l plane of the AFS[27,28] and STAR[18,23] pp CEP experiments…”

Decays of the f0(1370) scalar glueball candidate

“…Concerning the nature of the σ and f0(980) 0 ++ * Talk given at Q C D 1 8 2 1 s t International Conference in Quantum Chromodynamics 2-6 July 2018 Montpellier -Fr and has been interpreted as a clear manifestation that the f0(1370) meson is an isolated structure of limited width [19,20] (see fig 1 from ref [18]). This interpretation is based on STAR data [18,[21][22][23][24][25], on the scaling laws of CEP [8,26] and on results of the AFS experiment [27,28] at the CERN ISR. The STAR data have been discussed extensively in refs [19,20,29].…”