Central exclusive diffractive production of p(p)over-bar pairs in proton-proton collisions at high energies

We consider the central exclusive production of the p (p) over bar p in the continuum and via resonances in proton-proton collisions at high energies. We discuss the diffractive mechanism calculated within the tensor-Pomeron approach including Pomeron, Odderon, and Reggeon exchanges. The theoretical results are discussed in the context of existing WA102 and Intersecting Storage Rings experimental data, and predictions for planned or current experiments at the Relativistic Heavy Ion Collider and the LHC are presented. The distribution in y(diff), the rapidity distance between the proton and antiproton, is particularly interesting. We find a dip at y(diff) = 0 for the p (p) over bar production, in contrast to the pi(+)pi(-) and K+K- production. We predict also the p (p) over bar invariant-mass distribution to be less steep than for the pairs of pseudoscalar mesons. We argue that these specific differences for the p (p) over bar production with respect to the pseudoscalar meson pair production can be attributed to the proper treatment of the spin of produced particles. We discuss asymmetries that are due to the interference of C = +1 and C = -1 amplitudes of p (p) over bar production. We have also calculated the cross section for the pp -> pp Lambda(Lambda) over bar reaction. Here, the cross section is smaller, but the characteristic feature for d sigma/dy(diff) is predicted to be similar to p (p) over bar production. The presence of resonances in the p (p) over bar channel may destroy the dip at y(diff) = 0. This opens the possibility to study diffractively produced resonances. We discuss the observables suited for this purpose.