Next-to-Leading Order QCD Corrections to the Decay Width $H\to Z\gamma$

We present the analytic calculation of the two-loop QCD corrections to the decay width of a Higgs boson into a photon and a $Z$ boson. The calculation is carried out using integration-by-parts identities for the reduction to master integrals of the scalar integrals, in terms of which we express the amplitude. The calculation of the master integrals is performed using differential equations applied to a set of functions suitably chosen to be of uniform weight. The final result is expressed in terms of logarithms and polylogarithmic functions ${\text{Li}}_2$, ${\text{Li}}_3$, ${\text{Li}}_4$ and ${\text{Li}}_{2,2}$.