Production rate and ellipticity of lepton pairs from a rotating hot and dense QCD medium

TL;DR

This paper investigates how rotation in a hot, dense QCD medium affects lepton pair production, revealing enhancements in spectral functions and dilepton rates, azimuthal anisotropy, and the influence of angular velocity, temperature, and chemical potential.

Contribution

It introduces a detailed calculation of the photon polarization tensor and dilepton production in a rotating QCD medium, highlighting the effects of rotation on spectral functions, dilepton rates, and azimuthal anisotropy.

Findings

Spectral function and dilepton rate are enhanced in rotating medium.

Azimuthal anisotropy (elliptic flow) of dileptons is induced by rotation.

Rotation causes a suppression of the Debye mass and influences spin polarization effects.

Abstract

Using a current-current correlation function (CF), the photon polarization tensor is calculated for a rotating hot and dense QCD medium. The spectral function (SF) and the dilepton rate (DR) are estimated therefrom. Numerical results show that both SF and DR are enhanced in a rotating medium, especially in a low invariant mass region. SF and DR are also explored in the consequences of the interplay among the angular velocity, temperature and chemical potential. We also estimated the electromagnetic screening by calculating the Debye mass and it shows a suppression for a rotating QCD medium. The most interesting observation is the azimuthal anisotropy of the dilepton production, i.e, the elliptic flow $v_{2}$ of the lepton pair induced by the rotation as an external field. The competition between the centrifugal effect and the spin polarization effect due to rotation results in a convex down behaviour of the elliptic flow as a function of the transverse momentum in a relatively large magnitude of angular velocity. It is noticed that quark spin polarization induces a negative $v_2$ in the case of large angular velocity.