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We study the shear and bulk viscosities of partonic and hadronic matter as functions of temperature T within the parton-hadron-string dynamics (PHSD) off-shell transport approach. Dynamical hadronic and partonic systems in equilibrium are…

High Energy Physics - Phenomenology · Physics 2015-06-12 V. Ozvenchuk , O. Linnyk , M. I. Gorenstein , E. L. Bratkovskaya , W. Cassing

We consider an effective field theory description of beyond-quasi-particle excitations aiming to associate the transport properties of the system with the spectral density of states. Tuning various properties of the many-particle…

High Energy Physics - Phenomenology · Physics 2016-03-30 M. Horváth , A. Jakovác

A theoretical framework for the calculation of shear and bulk viscosities of hadronic matter at finite temperature is presented. The framework is based on the quasi-particle picture. It allows for an arbitrary number of hadron species with…

Nuclear Theory · Physics 2011-02-01 P. Chakraborty , J. I. Kapusta

We have explored the shear viscosity and electrical conductivity calculations for bosonic and fermionic medium, which goes from without to with magnetic field picture and then their simplified massless expressions. In presence of magnetic…

High Energy Physics - Phenomenology · Physics 2020-10-12 Jayanta Dey , Sarthak Satapathy , Prasanta Murmu , Sabyasachi Ghosh

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…

Quantum Gases · Physics 2015-07-15 J. A. Joseph , E. Elliott , J. E. Thomas

The shear viscosity $\eta$ has been calculated by using the Green-Kubo relation in the framework of a partonic transport approach solved at cascade level. We compare the numerical results for $\eta$ obtained from the Green-Kubo correlator…

Nuclear Theory · Physics 2015-09-01 S. Plumari , A. Puglisi , F. Scardina , V. Greco

The anti-de Sitter/conformal field theory correspondence (AdS/CFT) has been used to determine a lower bound on the ratio of shear viscosity $\left(\eta\right)$ to entropy density $(s)$ for strongly-coupled field theories with a gravity…

Strongly Correlated Electrons · Physics 2019-06-28 Matthew P. Gochan , Hua Li , Kevin S. Bedell

The ratio between the shear viscosity and the entropy $\eta/s$ is considered a universal measure of the strength of interactions in quantum systems. This quantity was conjectured to have a universal lower bound $(1/4\pi)\hbar/k_{B}$, which…

Strongly Correlated Electrons · Physics 2021-07-07 Sang Wook Kim , Geo Jose , Bruno Uchoa

The ratio of shear viscosity to volume density of entropy can be used to characterize how close a given fluid is to being perfect. Using string theory methods, we show that this ratio is equal to a universal value of $\hbar/4\pi k_B$ for a…

High Energy Physics - Theory · Physics 2007-05-23 P. Kovtun , D. T. Son , A. O. Starinets

The shear viscosity tensor of the superfluid Fermi gas in p-wave state with weak interaction is calculated at low temperatures, by using the Boltzmann equation approach. We consider the transition probabilities for the binary, decay and…

Quantum Gases · Physics 2016-03-09 Soudabe Nasirimoghadam , Roohollah Aliabadi , Mohamad Ali Shahzamanian

We determine the shear viscosity of the ultracold Fermi gas at unitarity in the normal phase using hydrodynamic expansion data. The analysis is based on a generalized fluid dynamic framework which ensures a smooth transition between the…

Quantum Gases · Physics 2017-08-16 Marcus Bluhm , Jiaxun Hou , Thomas Schaefer

We measure the shear viscosity in a two-component Fermi gas of atoms, tuned to a broad s-wave collisional (Feshbach) resonance. At resonance, the atoms strongly interact and exhibit universal behavior, where the equilibrium thermodynamic…

Quantum Gases · Physics 2012-01-18 C. Cao , E. Elliott , H. Wu , J. E. Thomas

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…

High Energy Physics - Phenomenology · Physics 2017-08-23 A. Jakovac

In this contribution we summarize recent progress in understanding the shear viscosity of strongly correlated dilute Fermi gases. We discuss predictions from kinetic theory, and show how these predictions can be tested using recent…

Nuclear Theory · Physics 2015-05-20 Thomas Schaefer

One considers the superfluid (SF) state of a Bose liquid with a strong repulsion between bosons, in which at T=0, along with a weak single-particle Bose-Einstein condensate (BEC), there exists an intensive pair coherent condensate (PCC),…

Soft Condensed Matter · Physics 2007-05-23 E. A. Pashitskii , S. V. Mashkevich , S. I. Vilchynskyy

In this study, we calculate the shear viscosity for rotating fermions with spin-half under conditions of high temperature and density. We employ the Kubo formalism, rooted in finite-temperature quantum field theory, to compute the field…

High Energy Physics - Phenomenology · Physics 2024-04-23 Sarthak Satapathy , Rajeev Singh , Pushpa Panday , Salman Ahamad Khan , Debarshi Dey

The ratio of shear viscosity ($\eta$) to entropy density ($s$) for an equilibrated system is investigated in intermediate energy heavy ion collisions below 100$A$ MeV within the framework of the Boltzmann-Uehling-Uhlenbeck (BUU) model .…

Nuclear Theory · Physics 2011-09-01 S. X. Li , D. Q. Fang , Y. G. Ma , C. L. Zhou

The applicability of the semiclassical Boltzmann transport theory is fundamentally challenged in strongly correlated systems where quasiparticle excitations are ill-defined. When the fermion spectral broadening becomes much larger than the…

Strongly Correlated Electrons · Physics 2026-05-29 Yi-Hui Xing , Wu-Ming Liu

Shear $\eta$ and bulk $\zeta$ viscosities are calculated in a quasiparticle model within a relaxation time approximation for pure gluon matter. Below $T_c$ the confined sector is described within a quasiparticle glueball model. Particular…

Nuclear Theory · Physics 2015-03-17 A. S. Khvorostukhin , V. D. Toneev , D. N. Voskresensky

We show how to describe the $T \neq 0$ behavior associated with the usual BCS- Bose Einstein condensation (BEC) crossover ground state. We confine our attention here to the BEC and near-BEC regime where analytical calculations are possible.…

Soft Condensed Matter · Physics 2011-09-13 Jelena Stajic , Qijin Chen , K. Levin