HOT-SPOTS AND TURBULENT INITIAL CONDITIONS OF QUARK-GLUON PLASMAS IN NUCLEAR COLLISIONS

As a result of multiple mini-jet production, initial conditions of the QCD plasma formed in ultrarelativistic nuclear collisions may be inho mogeneous, with large fluctuations of the local energy density (hot sp ots),and turbulent, with a chaotic initial transverse velocity field. Assuming rapid local thermalization, the evolution of such plasmas is computed using longitudinal boost-invariant (3+1)-dimensional hydrodyn amics. We compare the evolution in case that the speed of sound in the plasma is constant to one resulting from an equation of state involvi ng a strong first-order transition, with a minimum of the velocity of sound as a function of energy density, We find that azimuthally asymme tric fluctuations and correlations of the transverse energy flow, dE(p erpendicular to)/dy d phi, can develop in both cases due to the initia l inhomogeneities. Hot spots also enhance significantly high-k(perpend icular to) direct photon yields, In the case with a phase transition, the hadronization surface evolves into an unusual foam-like structure. Also in that case, we find that hadronization is considerably delayed relative to the ideal gas case, just as previous studies have found f or homogeneous initial conditions. The time-delay signature of a rapid cross-over transition region in the QCD equation of state (as observa ble via meson interferometry) is thus found to be remarkably robust to uncertainties in the initial conditions in heavy-ion reactions.