Diffractive mechanisms in pp\rightarrow pp pi0 reaction at high energies

Abstract

We present a study of exclusive production of π 0 meson in proton-proton collisions at high energies. Both diffractive bremsstrahlung (Drell-Hiida-Deck type model), photon-photon, photonomega and photon-odderon exchange mechanisms are included in the calculation. The π 0 -bremsstrahlung contribution dominates at large (forward, backward) pion rapidities and contributes at small π 0 p invariant mass and could be therefore misinterpreted as the Roper resonance N * (1440). Large cross sections of the order of mb are predicted. We predict strong dependence of the slope in t (squared four-momentum transfer between ingoing and outgoing proton) on the mass of the supplementary excited π 0 p system. At high energy and midrapidity, the photonphoton contribution dominates over the diffractive components, however, the corresponding cross section is rather small. The photon-odderon and odderon-photon contributions are included in addition and first estimates (upper limits) of their contributions are presented. We suggest a search for the odderon contribution at midrapidity and at p ⊥,π 0 ∼ 0.5 GeV. Our predictions are ready for verification at LHC. The bremsstrahlung mechanisms discussed here contribute also to the pp → p(nπ + ) reaction. Both channels give a sizable contribution to the low-mass single diffractive cross section and must be included in extrapolating the measured experimental single diffractive cross section. XXI International Workshop on Deep-Inelastic Scattering and Related PoS(DIS 2013)305Diffractive mechanisms in pp → ppπ 0 reaction at high energies Piotr LEBIEDOWICZ (a)IP (q2) Figure 1: Diagrams of the π 0 -bremsstrahlung amplitudes driven by the pomeron (IP) exchange in the ppcollisions: (a) pion exchange, (b) proton exchange, and (c) direct production.