Causal viscous hydrodynamics for central heavy-ion collisions II: meson spectra and HBT radii

Causal viscous hydrodynamic fits to experimental data for pion and kaon transverse momentum spectra from central Au + Au collisions at are presented. Starting the hydrodynamic evolution at 1 fm/c and using small values for the relaxation time, reasonable fits up to moderate ratios, η/s≃0.4, can be obtained. It is found that a percentage of roughly 50 η/s to 75 η/s of the final meson multiplicity is due to viscous entropy production. Finally, it is shown that with increasing viscosity, the ratio of HBT radii R_out/R_side approaches and eventually matches the experimental data.