Heavy quark diffusion coefficient with gradient flow

We calculate chromoelectric and chromomagnetic correlators in quenched QCD at $1.5{T}_{c}$ ${10}^{4}{T}_{c}$, with the aim to estimate heavy quark diffusion coefficient leading order inverse mass expansion, ${\ensuremath{\kappa}}_{\mathrm{E}}$, as well of first mass-suppressed correction, ${\ensuremath{\kappa}}_{\mathrm{B}}$. use gradient flow for noise reduction. At we obtain $1.70\ensuremath{\le}{\ensuremath{\kappa}}_{\mathrm{E}}/{T}^{3}\ensuremath{\le}3.12$ $1.03<{\ensuremath{\kappa}}_{\mathrm{B}}/{T}^{3}<2.61$. The latter implies that effects are 20% bottom quarks 34% charm this temperature.