Quark and gluon jet conversions in the quark-gluon plasma

Quark and gluon jet conversion rates in the quark-gluon plasma through both the elastic scattering process $q(\bar q)g\to gq(\bar q)$ and the inelastic scattering process $q\bar q\leftrightarrow gg$ are studied in the lowest order in Quantum Chromodynamics. Using the Fokker-Planck approach to treat the propagation and conversion of quark and gluon jets in the expanding quark-gluon plasma produced in relativistic heavy ion collisions, we have found a net conversion of quark jets to gluon jets. This reduces the difference between the nuclear modification factors for quark and gluon jets in central heavy ion collisions and thus enhances the $p/\pi^+$ ratio at high transverse momentum. To explain the observed similarity between the $p/\pi^+$ ratio at high transverse momentum in central Au+Au collisions at $\sqrt{s}_{NN}=200$ GeV and that in d+Au collisions at same energy requires, however, a much larger net quark to gluon jet conversion rate than the calculated one. Implications of our results are discussed