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

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 0bremsstrahlung 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.

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