Mott effect at the chiral phase transition and anomalous J/ψ suppression

Abstract

We investigate the in-medium modification of the charmonium break-up process due to the Mott effect for light (π) and open-charm (D, D * ) mesons at the chiral/deconfinement phase transition. A model calculation for the process J/ψ + π → D +D * +h.c. is presented which demonstrates that the Mott effect for the D-mesons leads to a threshold effect in the thermal averaged break-up cross section. This effect is suggested as an explanation of the phenomenon of anomalous J/ψ suppression in the CERN NA50 experiment.

Kinetic description of charmonium production in high-energy nuclear collisions

“…Unless one employs exceptionally large cross sections, it seems unlikely that hadronic dissociation can be at all relevant. A way out was proposed in [42], where it was argued that the QCD analogue of the Mott transition in an electron plasma may produce an onset behavior in thermally averaged cross section when the Mott temperature T Mott ∼ T c is reached. However, this framework has not yet been constrained by lattice EoS results.…”

Dmesons at finite temperature and density in the Polyakov–Nambu–Jona-Lasinio model

“…The reverse process [6][7][8] of charmonium regeneration by open charm recombination should play a dominant role for J/ψ production at LHC [9,10] where charm is abundant in the medium. Since either dropping masses [11,12] or increasing widths [13,14] of the D mesons in a hot and dense medium can lead to a lowering of the reaction threshold and thus to a strong increase of the rate for the processes (1), both effects may contribute to an explanation of the anomalous J/ψ suppression found in the NA50 experiment [15][16][17] and subsequently confirmed by NA60 [18,19] and PHENIX [20]. For a recent review, see [21].…”

“…Therefore, it seems likely that a quark hadron duality similar to that discussed for lowmass dilepton production [28] can be observed also in the D meson channel at the deconfinement transition. The spectral broadening of D mesons rather than their mass shift has been suggested for an explanation of anomalous J/ψ suppression in [13,14]. This question, however, awaits a thorough investigation.…”

Effect of in-medium spectral density of D and mesons on the dissociation in hadronic matter

“…In this connection the inelastic reaction rates of J/ψ in the hadronic phase have been studied using different effective hadronic models [21,22,23]. In addition, several theoretical efforts [24,25,26,27,28,29,30,31,32,33,34,35,36,37] have been made in order to understand the in-medium behavior of charmed mesons using different hadronic models e.g. QCD sum rules [25,26,27], Quark-Meson Coupling (QMC) [28], Nambu-Jona-Lasinio (NJL) model [29,30].…”

“…QCD sum rules [25,26,27], Quark-Meson Coupling (QMC) [28], Nambu-Jona-Lasinio (NJL) model [29,30]. Most of them have predicted a larger mass drop of open-charm mesons than that of J/ψ which may help to explain the J/ψ suppression in a hadronic environment [24,25,32] although a width enhancement with negligible mass shift of open charm mesons [31,30,34] have also been suggested in order to explain the suppression [30,34].…”