Speaker
Description
Heavy quark (HQ) momentum ($\kappa$) and spatial diffusion ($D_s$) coefficients are computed in a non-perturbative thermal QCD medium in the presence of a background magnetic field of arbitrary strength. Both perturbative (Yukawa) and non-perturbative (string) effects are incorporated via the in-medium HQ potential, obtained from the resummed
gluon propagator ($D_{\mu\nu}$). To that end, an ansatz is used for the non-perturbative gluon propagator such that it reproduces the string term in the Cornell potential (in vacuum). The heavy quark self energy is then calculated using $D_{\mu\nu}$, and the momentum diffusion coefficients ($\kappa_L$, $\kappa_T$) obtained therefrom. It is observed that the $\kappa$ are anisotropic even in the static heavy
quark limit ($\vec{v}\to 0$), with the magnetic field direction defining the axis of anisotropy. This anisotropy originates from
restrictions on longitudinal momentum diffusion in the gluon spectral function, and naturally leads to two spatial
diffusion coefficients ($D_s^L$ , $D_S^T$ ). However, the ratio of the string to Yukawa contribution in $\kappa$ is found to be isotropic, so that, $\kappa_L^Y\neq \kappa_T^Y\neq \kappa_L^s\neq\kappa_T^s$, but $\frac{\kappa_L^s}{\kappa^Y_L}=\frac{\kappa_T^s}{\kappa^Y_T}$. Non-perturbative (string) contributions are found to be dominant at low temperatures. These results can serve as a more consistent input for Langevin based calculations of the heavy quark directed flow ($v_1$) at RHIC and LHC energies.
