Study of central exclusive processes and forward neutrons with the CMS detector

by Dr Oliver Suranyi (Eotvos Lorand University)

Tuesday 25 Jan 2022, 11:00 → 13:00 US/Eastern

The properties of the strong interaction are being studied by the experiments of the LHC. Strong interaction processes with low momentum transfer that cannot be described by perturbation theory are among the hot topics of high-energy physics. Another focus of the experiments is the study of collisions of high-energy heavy nuclei, in which conditions similar to the matter of the Universe microseconds after the Big Bang are reproduced. In this talk, I will present two main topics:

1) The analysis of central exclusive π+π− production [1,2]: In central exclusive production, the two colliding protons remain intact and particles are produced via the interaction of two emitted objects. At LHC energies, the exchange of color singlet gluon states dominate, which allows us to study the non-perturbative regime of the strong interaction. In this talk, I will review the recently published CMS results on exclusive pi+pi- production. I will also discuss a new, exciting analysis idea: the detection of odderon effects in p+A collisions. The odderon is the odd counterpart of the pomeron, and was observed recently by the TOTEM and DØ Collaborations.

2) Detecting spectator neutrons with the CMS zero degree calorimeters (ZDC) [3]: The ZDC detects the forward neutrons emitted from the spectator nuclei, used to measure the centrality of heavy ion collisions and tag ultraperipheral collisions. In this talk, I will discuss the various studies and analysis techniques developed for the CMS ZDC: the detector simulation, signal extraction, calibration, and pileup correction. Finally, I will present applications for the ZDC.

[1] CMS Collaboration, ,,Study of central exclusive π+π− production in proton-proton collisions at √s = 5.02 and 13 TeV”, Eur. Phys. J. C 80 (2020), no. 8, 718, doi:10.1140/epjc/s10052-020-8166-5, arXiv:2003.02811.
[2] O. Suranyi, ,,Study of central exclusive production in pp collisions at √s = 5.02 and 13 TeV”, CMS Analysis Note CMS-AN-15/288 (2020).
[3] O. Suranyi et al., ,,Performance of the CMS Zero Degree Calorimeters in pPb collisions at the LHC”, JINST 16 P05008 (2021), doi:10.1088/1748-0221/16/05/P05008, arXiv:2102.06640.

 

Recording: (passcode: M^SF4Wcz )

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