Gluon fusion production at NLO: merging the transverse momentum and the high-energy expansions
Luigi Bellafronte, G. Degrassi, Pier Paolo Giardino, Ramona Gröber, Marco Vitti
Abstract
The virtual corrections to gg → HH and gg → ZH are analytically evaluated combining an expansion in the small transverse momentum of the final particles with an expansion valid at high energies. The two expansion methods describe complementary regions of the phase space and we merge their results, extending the range of validity of \nboth expansions using Padé approximants. We show that this approach can reproduce the available numerical results retaining the exact top quark mass dependence with an accuracy below the 1% level. Our results allow a fast and flexible evaluation of the virtual corrections \nof the considered processes. Furthermore, they are available in different renormalisation schemes of the top quark mass.