cross section
نویسندگان
چکیده
We calculate the cross section for the dissociation of J/ψ by kaons within the framework of a meson exchange model. We find that, depending on the values of the coupling constants used, the cross section can vary from 5 mb to 30 mb at √ s ∼ 5 GeV. In relativistic heavy ion collisions J/ψ suppression has been recognized as an important tool to identify the possible phase transition to quark-gluon plasma (QGP) [1] (for a review of data and interpretations see refs. [2,3]). Since there is no direct experimental information on J/ψ absorption cross sections by hadrons, several theoretical approaches have been proposed to estimate their values. In order to elaborate a theoretical description of the phenomenon, we have first to choose the relevant degrees of freedom. Some approaches were based on charm quark-antiquark dipoles interacting with the gluons of a larger (hadron target) dipole [4–6] or quark exchange between two (hadronic) bags [7,8], or QCD sum rules [9–11], whereas other works used the meson exchange mechanism [12–17]. In this case it is not easy to decide in favor of quarks or hadrons because we are dealing with charm quark bound states, which are small and massive enough to make perturbation theory meaningful, but not small enough to make non-perturbative effects negligible [9–11,18]. The meson exchange approach was applied basically to J/ψ −π and J/ψ −ρ cross sections, with the only exception of ref. [13] where J/ψ−K cross section was also estimated. However, as pointed out in ref. [14], there are some inconsistencies in the Lagrangians defined in ref. [13]. In this work we will evaluate the J/ψ − K cross section using a meson-exchange model as in ref. [13], but we will treat the VVV and four-point couplings in the effective Lagrangians as in ref. [14]. As in refs. [13–16] we start with the SU(4) La-grangian for the pseudo-scalar and vector mesons. The effective Lagrangians relevant for the study of the J/ψ absorption by kaons are:
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