Study of central exclusive "Equation missing" production in proton-proton collisions at $$\sqrt{s} = 5.02$$ and 13TeV

Abstract

Central exclusive and semiexclusive production of "Equation missing" pairs is measured with the CMS detector in proton-proton collisions at the LHC at center-of-mass energies of 5.02 and 13TeV. The theoretical description of these nonperturbative processes, which have not yet been measured in detail at the LHC, poses a significant challenge to models. The two pions are measured and identified in the CMS silicon tracker based on specific energy loss, whereas the absence of other particles is ensured by calorimeter information. The total and differential cross sections of exclusive and semiexclusive central "Equation missing" production are measured as functions of invariant mass, transverse momentum, and rapidity of the "Equation missing" system in the fiducial region defined as transverse momentum "Equation missing" and pseudorapidity "Equation missing". The production cross sections for the four resonant channels "Image missing" , "Equation missing", "Image missing" , and "Image missing" are extracted using a simple model. These results represent the first measurement of this process at the LHC collision energies of 5.02 and 13TeV.

Recent CMS results on soft and small-x QCD physics

“…Central exclusive and semiexclusive production of π + π − pairs is measured with the CMS detector in pp collisions at the LHC at s of 5.02 and 13 TeV [8]. Exclusive events are selected by vetoing additional energy deposits in the calorimeters and by requiring two oppositely charged pions identified via their mean energy loss in the tracker detectors.…”