Photon and dilepton emission anisotropy for a magnetized quark-gluon plasma

Abstract

We study the higher-order anisotropy coefficients $v_4$ and $v_6$ in the photon and dilepton emission from a hot magnetized quark-gluon plasma. Together with the earlier predictions for $v_2$, these results show a distinctive pattern of the anisotropy coefficients in several kinematic regimes. In the case of photon emission, nonzero coefficients $v_n$ (with even $n$) have opposite signs at small and large values of the transverse momentum (i.e., $k_T\lesssim \sqrt{|eB|}$ and $k_T\gtrsim \sqrt{|eB|}$, respectively). Additionally, the $v_n$ signs alternate with increasing $n$, and their approximate values decrease as $1/n^2$ in magnitude. The anisotropy of dilepton emission is well pronounced only at large transverse momenta and small invariant masses (i.e., when $k_T\gtrsim \sqrt{|eB|}$ and $M\lesssim \sqrt{|eB|}$). The corresponding $v_4$ and $v_6$ coefficients are of the same magnitude and show a similar alternating sign pattern with increasing $n$ as in the photon emission.