Heavy quark diffusion coefficient with gradient flow

We calculate chromoelectric and chromomagnetic correlators in quenched QCD at 1. 5T₂ and 10^4T₂, with the aim to estimate the heavy quark diffusion coefficient at leading order in the inverse heavy quark mass expansion, ₄, as well as the coefficient of the first mass-suppressed correction, ₁. We use gradient flow for noise reduction. At 1. 5T₂ we obtain 1. 70₄/T^33. 12 and 1. 03<₁/T^3<2. 61. The latter implies that the mass-suppressed effects in the heavy quark diffusion coefficient are 20% for bottom quarks and 34% for charm quarks at this temperature.