Related papers: Minimum Shear Viscosity over Entropy Density at Ph…
We calculate the ratio eta/s, the shear viscosity (eta) to entropy density (s), which characterizes how perfect a fluid is, in weakly coupled real scalar field theories with different types of phase transitions. The mean-field results of…
The rich phenomena of the shear viscosity (eta) to entropy density (s) ratio, eta/s, in weakly coupled N-component scalar field theories are studied. eta/s can have a "double dip" behavior due to resonances and the phase transition. If an…
We show that in theories where the lowest energy excitations are not quasiparticles but they form a continuum, the shear viscosity to entropy density ratio goes to zero as the temperature goes to zero. In these theories therefore there is…
Nuclear multifragmentation in intermediate energy heavy ion collisions has long been associated with liquid-gas phase transition. We calculate the shear viscosity to entropy density ratio eta/s for an equilibrated system of nucleons and…
The ratio of shear viscosity to entropy density, $\eta/s$, is computed in various holographic geometries that break translation invariance (but are isotropic). The shear viscosity does not have a hydrodynamic interpretation in such…
We reexamine the possibility of employing the viscosity over entropy density ratio as a diagnostic tool to identify a phase transition in hadron physics to the strongly coupled quark-gluon plasma and other circumstances where direct…
We examine the structure of the shear viscosity to entropy density ratio eta/s in holographic theories of gravity coupled to a scalar field, in the presence of higher derivative corrections. Thanks to a non-trivial scalar field profile,…
Shear viscosity (eta) of QCD in the hadronic phase is computed by the coupled Boltzmann equations of pions and nucleons in low temperatures and low baryon number densities. The eta to entropy density ratio eta/s maps out the nuclear…
Transport coefficeints, in particular the shear viscosity to entropy density ratio is studied in systems where the small-width quasiparticle assumption is not valid. It is found that $\eta/s$ has no unversal lower bound, the minimal value…
Using chiral perturbation theory we investigate the QCD shear viscosity ($\eta $) to entropy density ($s$) ratio below the deconfinement temperature ($\sim 170$ MeV) with zero baryon number density. It is found that $\eta /s$ of QCD is…
There have been a number of forms of a conjecture that there is a universal lower bound on the ratio, eta/s, of the shear viscosity, eta, to entropy density, s, with several different domains of validity. We examine the various forms of the…
The shear viscosity to the entropy density ratio $\eta/s$ of the anisotropic superfluid has been calculated by means of the gauge/gravity duality in the presence of the {\it dark matter} sector. The {\it dark matter} has been described by…
We study finite temperature transport in the Luttinger-Abrikosov-Beneslavskii phase -- an interacting, scale invariant, non-Fermi liquid phase found in quadratic semimetals. We develop a kinetic equation formalism to describe the d.c.…
The lower bound of the shear viscosity to entropy density ratio is examined using an exact representation of the ratio through the density of states. It is shown that the lower bound in a generic physical system is not universal, its value…
We calculate the shear viscosity to entropy density ratio in pure SU(N) Yang-Mills theory below the critical temperature using the strong coupling expansion. The result for the eta/s ratio for temperatures around the phase transition is…
We extract the shear viscosity to entropy density ratio \eta/s of cold fermionic atoms in the unitarity limit from experimental data on the damping of collective excitations. We find that near the critical temperature \eta/s is roughly…
We investigate the low-temperature behavior of the ratio between the shear viscosity \eta and the entropy density s in the unitary Fermi gas by using a model based on the zero-temperature spectra of both bosonic collective modes and…
We compute the shear viscosity, $\eta$, at general temperatures $T$, in a BCS-BEC crossover scheme which is demonstrably consistent with conservation laws. The study of $\eta$ is important because it constrains microscopic theories by…
Starting from relativistic quantum field theories, Kovtun et al. (2005) have quite recently proposed a lower bound eta/s >= hbar /(4 pi kB), where eta is the shear viscosity and s the volume density of entropy for dense liquids. If their…
We precisely measure the shear viscosity for a resonantly interacting Fermi gas as a function of temperature, from nearly the ground state through the superfluid phase transition at a critical temperature $T_c$. Using an iterative method to…