Running of the top quark mass at NNLO in QCD

The running of the top quark mass ($m_\mathrm{t}$) is probed at the next-to-next-to-leading order (NNLO) in quantum chromodynamics (QCD) for the first time. The result is obtained by comparing calculations in the modified minimal subtraction ($\mathrm{\bar{MS}}$) renormalisation scheme to a differential measurement of the top quark-antiquark ($\mathrm{t\bar{t}}$) production cross section at $\sqrt{s} = 13~\mathrm{TeV}$. The scale dependence of $m_\mathrm{t}$ is extracted as a function of the invariant mass of the $\mathrm{t\bar{t}}$ system, up to an energy scale of about $0.5~\mathrm{TeV}$. The observed running is found to be in good agreement with the three-loop solution of the QCD renormalisation group equations.