Ratios of heavy baryons to heavy mesons in relativistic nucleus-nucleus collisions

Abstract

Heavy baryon/meson ratios Lambda(c)/D(0) and Lambda(b)/(B) over bar (0) in relativistic heavy ion collisions are studied in the quark coalescence model. For heavy baryons, we include production from coalescence of heavy quarks with free light quarks as well as with bounded light diquarks that might exist in the strongly coupled quark-gluon plasma produced in these collisions. Including the contribution from decays of heavy hadron resonances and also that due to fragmentation of heavy quarks that are left in the system after coalescence, the resulting Lambda(c)/D(0) and Lambda(b)/(B) over bar (0) ratios in midrapidity (vertical bar y vertical bar <= 0.5) from central Au + Au collisions at root s N N = 200 GeV are about a factor of five and ten, respectively, larger than those given by the thermal model, and about a factor of ten and twelve, respectively, larger than corresponding ratios in the PYTHIA model for pp collisions. These ratios are reduced by a factor of about 1.6 if there are no diquarks in the quark-gluon plasma. The transverse momentum dependence of the heavy baryon/meson ratios is found to be sensitive to the heavy quark mass, with the Lambda(b)/(B) over bar (0) ratio being much flatter than the Lambda(c)/D(0) ratio. The latter peaks at the transverse momentum p(T) similar or equal to 0.8 GeV but the peak shifts to p(T) similar or equal to 2 GeV in the absence of diquarks.