Interactions between heavy quarks and tilted QGP fireballs in 200 A GeV Au+Au collisions

Heavy quark observables are applied to probe the initial energy density distribution with violation of longitudinal boost invariance produced in relativistic heavy-ion collisions.Using an improved Langevin model coupled to a(3+1)-dimensional viscous hydrodynamic model,we study the nuclear modification factor(R_(AA)) and directed flow(v_(1)) and elliptic flow(v_(2)) coefficients of heavy mesons and their decayed electrons at an RHIC energy.We find that the counter-clockwise tilt of nuclear matter in the reaction plane results in a positive(negative) heavy flavor vi in the backward(forward) rapidity region,whose magnitude increases with the heavy quark transverse momentum.The difference in the heavy flavor R_(AA) between different angular regions is also proposed as a complementary tool to characterize the asymmetry of the medium profile.Our model results are consistent with currently available data at the RHIC and provide predictions that can be tested by future measurements.