Lattice B-field correlators for heavy quarks

We analyze the color -magnetic (or " B " ) field two -point function that encodes the finite -mass correction to the heavy -quark momentum -diffusion coefficient. The simulations are done on fine isotropic lattices in the quenched approximation at 1. 5 T c , using a range of gradient flow times for noise suppression and operator renormalization. The continuum extrapolation is performed at fixed flow time followed by a second extrapolation to zero flow time. Perturbative calculations to next -to -leading order of this correlation function, matching gradient -flowed correlators to MS, are used to resolve nontrivial renormalization issues. We perform a spectral reconstruction based on perturbative model fits to estimate the coefficient kappa B of the finite -mass correction to the heavy -quark momentum -diffusion coefficient. The approach we present here yields high -precision data for the correlator with all renormalization issues incorporated at next -to -leading order and is also applicable for actions with dynamical fermions.