Virtual corrections to gg → ZH via a transverse momentum expansion

We compute the next-to-leading virtual QCD corrections to partonic cross section of production a Higgs boson in association with $Z$ gluon fusion. The calculation is based on recently introduced method evaluating amplitude via an expansion terms small transverse momentum. generalize case different masses final state and process not symmetric forward-backward direction exchange. Our analytic approach gives very good approximation (better than percent) center mass energy region up $\sim 750 \,\textrm{GeV}$, where at LHC 98\%$ total hadronic concentrated.