Effective holographic models for QCD: Thermodynamics and viscosity coefficients

A finite-temperature extension of the effective holographic models for QCD (EHQCD), proposed in Ref. [Ballon-Bayona et al., Phys. Rev. D 97, 046001 (2018).], is investigated present work. EHQCD are characterized by two parameters, conformal dimension relevant operator that deforms field theory and associated coupling. We find black hole solutions appear at temperatures higher than some temperature ${T}_{\mathrm{min}}$ can be categorized into classes: large small holes. thermally stable it therefore interpreted as gravity dual a nonconformal plasma. hole, on other hand, unstable. show thermodynamic quantities such entropy density $s$, specific heat ${C}_{V}$, speed sound ${c}_{s}$ sensitive to model parameters. investigate perturbations calculate viscosity coefficients corresponding For shear viscosity, we confirm ratio $\ensuremath{\eta}/s$ given universal result $1/4\ensuremath{\pi}$. bulk $\ensuremath{\zeta}/s$ varies with temperature, displaying rapid growth close ${T}_{\mathrm{min}}$, compare our results lattice $SU({N}_{C})$ they compatible long coupling fixed appropriately function dimension. also against JETSCAPE Collaboration obtained from analysis experimental data heavy ion collisions.