Gabriel S. Denicol

Importance of the Bulk Viscosity of QCD in Ultrarelativistic Heavy-Ion Collisions

We investigate the consequences of a nonzero bulk viscosity coefficient on the transverse momentum spectra, azimuthal momentum anisotropy, and multiplicity of charged hadrons produced in heavy ion collisions at LHC energies. The agreement between a realistic 3D hybrid simulation and the experimentally measured data considerably improves with the addition of a bulk viscosity coefficient for strongly interacting matter. This paves the way for an eventual quantitative determination of several QCD transport coefficients from the experimental heavy ion and hadron-nucleus collision programs.

Influence of Shear Viscosity of Quark-Gluon Plasma on Elliptic Flow in Ultrarelativistic Heavy-Ion Collisions

We investigate the influence of a temperature-dependent shear viscosity over entropy density ratio η/s on the transverse momentum spectra and elliptic flow of hadrons in ultrarelativistic heavy-ion collisions. We find that the elliptic flow in √S(NN)=200  GeV Au+Au collisions at RHIC is dominated by the viscosity in the hadronic phase and in the phase transition region, but largely insensitive to the viscosity of the quark-gluon plasma (QGP). At the highest LHC energy, the elliptic flow becomes sensitive to the QGP viscosity and insensitive to the hadronic viscosity.

Event-by-event distributions of azimuthal asymmetries in ultrarelativistic heavy-ion collisions

Relativistic dissipative fluid dynamics is a common tool to describe the space-time evolution of the strongly interacting matter created in ultrarelativistic heavy-ion collisions. For a proper comparison to experimental data, fluid-dynamical calculations have to be performed on an event-by-event basis. Therefore, fluid dynamics should be able to reproduce, not only the event-averaged momentum anisotropies, 〈vn〉, but also their distributions. In this paper, we investigate the event-by-event distributions of the initial-state and momentum anisotropies en and vn, and their correlations. We demonstrate that the event-by-event distributions of relative vn fluctuations are almost equal to the event-by-event distributions of corresponding en fluctuations, allowing experimental determination of the relative anisotropy fluctuations of the initial state. Furthermore, the correlation c(v2,v4) turns out to be sensitive to the viscosity of the fluid providing an additional constraint to the properties of the strongly interacting matter.

Bulk viscosity effects in event-by-event relativistic hydrodynamics

Bulk viscosity effects on the collective flow harmonics in heavy-ion collisions are investigated, on an event-by-event basis, using a newly developed 2+1 Lagrangian hydrodynamic code named v-usphydro, which implements the smoothed particle hydrodynamics algorithm for viscous hydrodynamics. A new formula for the bulk viscous corrections present in the distribution function at freeze-out is derived, starting from the Boltzmann equation for multi-hadron species. Bulk viscosity is shown to enhance the collective flow Fourier coefficients from

Production of photons in relativistic heavy-ion collisions

{v}_{2}({p}_{T})

Influence of a temperature-dependent shear viscosity on the azimuthal asymmetries of transverse momentum spectra in ultrarelativistic heavy-ion collisions

to

Transport coefficients of bulk viscous pressure in the 14-moment approximation

{v}_{5}({p}_{T})

Studying the validity of relativistic hydrodynamics with a new exact solution of the Boltzmann equation

when

Moving Forward to Constrain the Shear Viscosity of QCD Matter.

{p}_{T}\ensuremath{\sim}1

Solutions of Conformal Israel-Stewart Relativistic Viscous Fluid Dynamics

\char21{}2.5 GeV, even when the bulk viscosity to entropy density ratio,