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We present a modification of a recently developed volume of fluid method for multiphase problems, so that it can be used in conjunction with a fractional step-method and fast Poisson solver, and validate it with standard benchmark problems.…

Fluid Dynamics · Physics 2018-07-06 Marco Edoardo Rosti , Francesco De Vita , Luca Brandt

We calculate for the first time the shear viscosity of ultrarelativistic Boson systems in the presence of a Bose-Einstein condensate (BEC). Two different methods are used. One is the Grad's method of moments and another is the Green-Kubo…

High Energy Physics - Phenomenology · Physics 2019-11-19 Zhengyu Chen , Carsten Greiner , Zhe Xu , Pengfei Zhuang

The $p$-wave superfluid state is a promising spin-triplet and non $s$-wave pairing state in an ultracold Fermi gas. In this work we study the low-temperature shear viscosity of a one-component $p$-wave superfluid Fermi gas, by means of Kubo…

Quantum Gases · Physics 2021-04-14 Seyed Mostafa Moniri , Heshmatollah Yavari , Elnaz Darsheshdar

I derive an exact integral expression for the ratio of shear viscosity over entropy density $\frac{\eta}{s}$ for the massless (critical) O(N) model at large N with quartic interactions. The calculation is set up and performed entirely from…

High Energy Physics - Theory · Physics 2021-12-23 Paul Romatschke

We investigate the temperature dependence of the shear viscosity and spin diffusion in a two-dimensional Fermi gas with contact interactions, as realized in ultra-cold atomic gases. We describe the transport coefficients in terms of a…

Quantum Gases · Physics 2012-07-16 Tilman Enss , Carolin Küppersbusch , Lars Fritz

A real-time thermal field theoretical calculation of shear viscosity has been described in the Kubo formalism for bosonic and fermionic medium. The two point function of viscous stress tensor in the lowest order provides one-loop skeleton…

Nuclear Theory · Physics 2014-04-21 Sabyasachi Ghosh

We derive an expression for the superfluid density of a uniform two-component Fermi gas through the BCS-BEC crossover in terms of the thermodynamic potential in the presence of an imposed superfluid flow. Treating the pairing fluctuations…

Other Condensed Matter · Physics 2008-12-12 E. Taylor , A. Griffin , N. Fukushima , Y. Ohashi

We present an ab initio determination of the shear viscosity for the unitary Fermi gas based on finite temperature quantum Monte Carlo (QMC) calculations and the Kubo linear-response formalism. The results are confronted with the bound for…

Quantum Gases · Physics 2013-08-02 Gabriel Wlazłowski , Piotr Magierski , Aurel Bulgac , Kenneth J. Roche

We study the zero temperature non-equilibrium dynamics of a fermionic superfluid in the BCS limit and in the presence of a drive leading to a time dependent chemical potential $\mu(t)$. We choose a periodic driving protocol characterized by…

Quantum Gases · Physics 2013-10-29 Analabha Roy , Raka Dasgupta , Sanhita Modak , Arnab Das , K. Sengupta

We derive an analytic expression for the shear viscosity of an ultra-relativistic gas in presence of both elastic $2\to 2$ and inelastic $2\leftrightarrow 3$ processes with isotropic differential cross sections. The derivation is based on…

High Energy Physics - Theory · Physics 2014-04-28 Andrej El , Francesco Lauciello , Christian Wesp , Ioannis Bouras , Zhe Xu , Carsten Greiner

The phonon contribution to the shear viscosity $\eta$ in superfluid neutron stars is calculated by assuming neutron pairing in a $^1S_0$ channel. The shear viscosity is obtained by means of variational methods for the solution of the…

High Energy Astrophysical Phenomena · Physics 2012-06-19 Laura Tolos , Cristina Manuel

We compute the contribution of phonons to the shear viscosity $\eta$ in superfluid neutron stars, assuming neutron pairing in a $^1S_0$ channel. We use a Boltzmann equation amended by a collision term that takes into account the binary…

Solar and Stellar Astrophysics · Physics 2013-05-29 Cristina Manuel , Laura Tolos

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…

Nuclear Theory · Physics 2014-11-20 Subrata Pal

In recent years, there has been a significant effort to extract the temperature-dependent shear ($\eta/s$) and bulk ($\zeta/s$) viscosity over entropy ratios of the quark-gluon plasma from a global comparison of heavy-ion data with results…

Nuclear Theory · Physics 2023-02-28 Fernando G. Gardim , Jean-Yves Ollitrault

The transport property of cold and dense nucleon matter is important for nuclear physics but is relatively less studied than that at finite temperatures. In this paper, we present a primary study of bulk and shear viscosities in the limit…

Nuclear Theory · Physics 2025-04-09 Jianing Li , Weiyao Ke

The viscosity of hadronic matter is studied using a classical evaluation of the scattering angle and a quantum mechanical discussion based on phase shifts from a potential. Semi classical limits of the quantum theory are presented. A hard…

Nuclear Theory · Physics 2010-09-30 Aram Z. Mekjian

We study finite-temperature properties of a two-dimensional superfluid made of ultracold alkali-metal atoms in the BCS-BEC crossover. We investigate the region below the critical temperature $T_{BKT}$ of the Berezinskii-Kosterlitz-Thouless…

Quantum Gases · Physics 2013-11-20 L. Salasnich , P. A. Marchetti , F. Toigo

We study hydrodynamic fluctuations in a non-relativistic fluid. We show that in three dimensions fluctuations lead to a minimum in the shear viscosity to entropy density ratio $\eta/s$ as a function of the temperature. The minimum provides…

Quantum Gases · Physics 2013-03-14 Clifford Chafin , Thomas Schaefer

We present a detailed analysis of the contribution of small-angle Nambu-Goldstone boson (phonon) collisions to the shear viscosity, $\eta$, in a superfluid atomic Fermi gas close to the unitarity limit. We show that the experimental values…

Quantum Gases · Physics 2013-07-02 Massimo Mannarelli , Cristina Manuel , Laura Tolos

We investigate the shear viscosity $\eta$ and the entropy density $s$ of strongly coupled $\mathcal{N}=4$ super Yang-Mills (SYM) plasma in late time of hydrodynamic evolution with AdS/CFT duality and Bjorken scaling. We use correlation…

High Energy Physics - Phenomenology · Physics 2011-04-07 Shi Pu , Qun Wang