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

Using a current-current correlation function, 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 behavior 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.

Automated summary

Using current-current correlation function, the photon polarization tensor is computed for a rotating hot and dense QCD medium. The spectral function and dilepton rate are then estimated, showing enhancement in a rotating medium, especially at low invariant masses. The effects of angular velocity, temperature, and chemical potential on the spectral function and dilepton rate are explored. Electromagnetic screening is also investigated, with the calculation of Debye mass indicating suppression in a rotating QCD medium. The most interesting observation is the azimuthal anisotropy of dilepton production, where the elliptic flow v(2) induced by rotation as an external field exhibits a convex down behavior in the transverse momentum, due to competition between centrifugal effect and spin polarization effect.