Central exclusive production with the CMS experiment

We published a paper on the central exclusive and semi-exclusive production of π+π− pairs measured with the CMS detector in pp collisions at center-of-mass energies of √s=5.02 and 13 TeV [1]. 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 semi-exclusive central π+π− production are measured as functions of invariant mass, transverse momentum, and rapidity of the π+π− system in the fiducial region defined as transverse momentum pT,π > 0.2 GeV and pseudorapidity |ηπ|<2.4 (Fig. 1). The production cross sections for the four resonant channels f0(500), ρ0(770), f0(980), and f2(1270) are extracted using a simple model. These results represent the first measurement of this process at the LHC collision energies of 5.02 and 13 TeV [2].