Exclusive Diffractive Production of Pion Pairs and Resonances in Proton-Proton Collisions within Tensor Pomeron Approach

摘要

The central exclusive production of π~+π~- pairs in proton-(anti)proton collisions is studied in the framework of tensor pomeron model. We discuss the purely diffractive processes (dipion continuum, scalar and tensor resonant contributions) and the photoproduction processes (ρ~0 and Drell-Soding mechanism). The theoretical results are compared with the STAR, CDF and CMS experimental data. We show the influence of the experimental cuts on the integrated cross section and on various differential distributions for outgoing particles, e.g. the distributions in two-pion invariant mass and transverse momentum of the pion pair. We find that the relative contribution of resonant f_2(1270) and dipion continuum strongly depends on the cut on proton transverse momenta (or four-momentum transfer squared). In the case of exclusive central 4π production we include the contribution via the intermediate σσ and ρρ states. For both processes the theoretical results have been compared with the ISR experimental data and predictions for planned or being carried out experiments (e.g. STAR, ATLAS-ALFA) are presented.