Exclusive production of pi+ pi- pairs in proton-proton and proton-antiproton collisions

Abstract

We report on a detailed investigation of four-body $pp\to pp{\pi }^{+}{\pi }^{-}$ and $p\bar{p}\to p\bar{p}{\pi }^{+}{\pi }^{-}$) reactions which constitute an irreducible background to three-body processes $pp\to ppM$, where $M$ is a broad resonance in the ${\pi }^{+}{\pi }^{-}$ channel, e.g. $M=\sigma ,{\rho }^0,f_0(980),f_2(1275),f_0(1500)$. We include double-diffractive contribution (both pomeron and reggeon exchanges) as well as the pion-pion rescattering contributions. The first process dominates at higher energies and small pion-pion invariant masses while the second becomes important at lower energies and higher pion-pion invariant masses. We compare our results with the experimental data. We make predictions for future experiments at PANDA, RHIC, Tevatron and LHC energies. The two-dimensional distribution in rapidity space of pions $(y_{{\pi }^{+}},y_{{\pi }^{-}})$ is particularly interesting. The higher the incident energy, the higher preference for the same-hemisphere emission of pions. The processes considered constitute a sizeable contribution to the total nucleon-nucleon cross section as well as to pion inclusive cross section.

Comments: 3 pages, 2 figures, talk given at MESON2010 conference, Krakow, Poland, 10-15 June 2010