T-2, Nuclear and Particle Physics, Astrophysics and Cosmology

Collisional Dissociation of Heavy Mesons in Dense QCD Matter

Ivan Vitev
T-16 & P-25, LANL

In the last two years the measured large suppression of single non-photonic electrons in Au+Au collisions at RHIC has been an outstanding puzzle for heavy ion theory. The implied dramatic quenching of heavy quarks is incompatible with early PQCD calculations based on parton energy loss. In this talk we will show that, in contrast to light hadrons, heavy charm and beauty mesons tend to form early, inside the hot and dense quark-gluon plasma, and a different approach is required to describe their propagation and modification in the nuclear medium. By resumming the multiple scattering in the plasma, we will derive the collisional broadening of the meson’s transverse momentum and the distortion of its intrinsic lightcone wave function. The medium-induced dissociation probability of heavy mesons will be shown to be sensitive to the opacity of the quark-gluon plasma and the time dependence of its formation and evolution. We will solve the system of coupled rate equations that describe the competition between the fragmentation of c- and b-quarks and the QGP-induced dissociation of the D- and B-mesons to evaluate the quenching of heavy hadrons in nucleus-nucleus collisions. In contrast to previous results on heavy quark modification, our approach predicts suppression of B-mesons comparable to that of D-mesons at transverse momenta as low as 10 GeV. It provides the strongest justification for experimental upgrades at RHIC, aimed at direct and separate measurements of D- and B-meson production. This new theoretical approach allows for an improved description of the large attenuation of non-photonic electrons in central Au+Au reactions at RHIC.

This research is a part of LDRD DR project "Heavy Quarks as a Prove of a New State of Matter".


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