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Related papers: Spin density matrix for neutral $\rho$ mesons in a…

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We present a calculation of the spin alignment for unflavored vector mesons in thermalized quark-gluon plasma based on the Kubo formula in linear response theory. This is achieved by expanding the system to the first order of the coupling…

High Energy Physics - Phenomenology · Physics 2024-03-06 Wen-Bo Dong , Yi-Liang Yin , Xin-Li Sheng , Shi-Zheng Yang , Qun Wang

We compute the $00$ element of the spin density matrix, denoted as $\rho_{00}$ and called the spin alignment, up to the second order of the gradient expansion in local equilibrium by Zubarev's approach. In the first order, we obtain…

High Energy Physics - Phenomenology · Physics 2024-12-30 Shi-Zheng Yang , Xin-Qing Xie , Shi Pu , Jian-Hua Gao , Qun Wang

The shear viscosity of an interacting pion gas is studied using the Kubo formalism as a microscopic description of thermal systems close to global equilibrium. We implement the skeleton expansion in order to approximate the retarded…

High Energy Physics - Phenomenology · Physics 2012-09-05 Robert Lang , Norbert Kaiser , Wolfram Weise

We study the spin alignment of neutral rho mesons in a pion gas using spin kinetic or Boltzmann equations. The $\rho\pi\pi$ coupling is given by the chiral effective theory. The collision terms at the leading and next-to-leading order in…

Nuclear Theory · Physics 2024-02-07 Yi-Liang Yin , Wen-Bo Dong , Jin-Yi Pang , Shi Pu , Qun Wang

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

Owing to the Kubo relation, the shear viscosities of pionic and nucleonic components have been evaluated from their corresponding retarded correlators of viscous stress tensor in the static limit, which become non-divergent only for the…

Nuclear Theory · Physics 2015-09-15 Sabyasachi Ghosh

A new precise measurements of spin density matrix element $\rho_{00}$ of $K^*(892)^{\pm}$ mesons produced inclusively in neutron-carbon interactions at \~60 GeV have been carried out in the EXCHARM experiment at the Serpukhov accelerator.…

High Energy Physics - Experiment · Physics 2012-08-27 EXCHARM Collaboration

Shear viscosity of the classical $\Phi^4$ theory is measured using classical microcanonical simulation. To calculate the Kubo formula, we measure the energy-momentum tensor correlation function, and apply the Green-Kubo relation. Being a…

High Energy Physics - Theory · Physics 2015-11-11 M. M. Homor , A. Jakovac

We propose an improved quark coalescence model for spin alignment of vector mesons and polarization of baryons by spin density matrix with phase space dependence. The spin density matrix is defined through Wigner functions. Within the model…

Nuclear Theory · Physics 2020-09-16 Xin-Li Sheng , Qun Wang , Xin-Nian Wang

We use a recently improved density-matrix expansion to calculate the nuclear energy density functional in the framework of in-medium chiral perturbation theory. Our calculation treats systematically the effects from $1\pi$-exchange,…

Nuclear Theory · Physics 2015-05-14 N. Kaiser , W. Weise

We present a first-order dissipative spin hydrodynamic framework, where the spin chemical potential $\omega^{\mu\nu}$ is treated as the leading term in the hydrodynamic gradient expansion, i.e., $\omega^{\mu\nu}\sim \mathcal{O}(1)$. We…

Nuclear Theory · Physics 2024-10-08 Sourav Dey , Arpan Das

We have calculated the shear viscosity of pion medium, where propagating pion has some finite thermal width due to interaction with the low mass resonances, $\sigma$ and $\rho$. With the help of standard thermal field theoretical technique,…

Nuclear Theory · Physics 2017-09-12 Sabyasachi Ghosh , Gastao Krein , Saurav Sarkar

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

The mass shift, width broadening, and spectral density for the $\rho$ and $\omega$ mesons in a heat bath of nucleons and pions are calculated using a general formula which relates the self-energy to the real and imaginary parts of the…

Nuclear Theory · Physics 2009-11-07 V. L. Eletsky , M. Belkacem , P. J. Ellis , J. I. Kapusta

The rate of dilepton emission from a magnetized hot hadronic medium is calculated in the framework of real time formalism of finite temperature field theory. We evaluate the one loop self-energy of neutral rho-meson containing…

High Energy Physics - Phenomenology · Physics 2023-03-07 Rajkumar Mondal , Nilanjan Chaudhuri , Snigdha Ghosh , Sourav Sarkar , Pradip Roy

In this paper we provide a quantum field theoretical study on the shear and bulk relaxation times. First, we find Kubo formulas for the shear and the bulk relaxation times, respectively. They are found by examining response functions of the…

Nuclear Theory · Physics 2017-08-16 Alina Czajka , Sangyong Jeon

Starting with the polarization dependent Wigner function of vector mesons, we derive an expression for the 00-component ($\rho_{00}$) of spin density matrix in terms of the second order gradients of the vector meson distribution functions.…

Nuclear Theory · Physics 2024-03-29 Avdhesh Kumar , Philipp Gubler , Di-Lun Yang

We have evaluated the shear viscosity of pion gas taking into account its scattering with the low mass resonances, $\sigma$ and $\rho$ during propagation in the medium. The thermal width (or collisional rate) of the pions is calculated from…

Nuclear Theory · Physics 2014-04-08 Sabyasachi Ghosh , Gastão Krein , Sourav Sarkar

We study the spin response of cold dense neutron matter in the limit of zero momentum transfer, and show that the frequency dependence of the long-wavelength spin response is well constrained by sum-rules and the asymptotic behavior of the…

Nuclear Theory · Physics 2013-02-19 G. Shen , S. Gandolfi , S. Reddy , J. Carlson

We calculate the spectral function $A_\rho$ of the $\rho$ meson in nuclear matter. The calculation is performed in the {\it low density} approximation, where the in-medium self energy $\Sigma_{med}$ is completely determined by the vacuum…

Nuclear Theory · Physics 2009-11-06 M. Post , S. Leupold , U. Mosel
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