Coalescence model for Theta(c) pentaquark formation.

Abstract

We present a model for the formation of the charmed pentaquark c in hard scattering processes such as deep inelastic scattering, e+e− annihilation, and high-energy p¯p collisions. The model assumes that the cross section for c formation is proportional to the rate of production of pD − (or ¯pD +) pairs in close proximity both in momentum space and in coordinate space. The constant of proportionality is determined from the c 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 c events produced at LEP and the Tevatron.