Coalescence model for Θc pentaquark formation

We present a model for the formation of the charmed pentaquark Θc in hard scattering processes such as deep inelastic scattering, e+e- annihilation, and high-energy pp-bar collisions. The model assumes that the cross section for Θc formation is proportional to the rate of production of pD*- (or p-barD*+) pairs in close proximity both in momentum space and in coordinate space. The constant of proportionality is determined from the Θc cross section in deep inelastic scattering as reported by the H1 experiment. The HERWIG Monte Carlo is used to generate simulated DIS events and also to model the space-time structure of the final state. Requiring the proton and the D* be within a 100 MeV mass window and separated by a spacelike distance of no more than 2 fm, we find that a large 'coalescence enhancement factor' Fco ∼ 10 is required to account for the H1 signal. The same approach is then applied in order to estimate the number and characteristics of Θc events produced at LEP and the Tevatron. (author)