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A new mechanism for heavy quarkonium production in high-energy collisions called the s-channel cut was proposed in 2005 by Lansberg, Cudell, and Kalinovsky. We identify this mechanism physically as the production of a heavy quark and anti-quark that are on-shell followed by their rescattering to produce heavy quarkonium. We point out that in the NRQCD factorization formalism this rescattering mechanism is a contribution to the color-singlet model term at next-to-next-to-leading order in perturbation theory. Its leading contribution to the production rate can be calculated without introducing any additional phenomenological parameters. We calculate the charm-pair rescattering (or s-channel cut) contribution to the production of J/psi at the Tevatron and compare it to estimates by Lansberg et al. using phenomenological models. This contribution competes with the leading-order term in the color-singlet model at large transverse momentum but is significantly smaller than the next-to-leading-order term. We conclude that charm-pair rescattering is not a dominant mechanism for charmonium production in high-energy collisions.
Quarkonium production in high-energy proton (deuteron)-nucleus collisions is investigated in the color glass condensate framework. We employ the color evaporation model assuming that the quark pair produced from dense small-x gluons in the nuclear ta
A short historical review is made of charged particle production at high energy proton synchrotrons and at pp and {p}p colliders. The review concerns mainly low p_t processes, including diffraction processes, and fragmentation of nuclei in nucleus-nu
Event generators are an indispensable tool for the preparation and analysis of particle-physics experiments. In this contribution, physics principles underlying the construction of such computer programs are discussed. Results, within and beyond the
It is shown that hadron abundances in high energy e+e-, pp and p{bar p} collisions, calculated by assuming that particles originate in hadron gas fireballs at thermal and partial chemical equilibrium, are in very good agreement with the data. The fre
We perform numerical comparison of the fragmentation mechanism of charmonium production ($g,gto c,bar{c}$ followed by $ctopsi,c$) with the full leading order calculation ($g,gtopsi,c,bar{c}$ at ${O} (alpha_s^4)$). We conclude that the non-fragmentati