QCD corrections to vector boson pair production in gluon fusion at the LHC

I will elaborate on the calculation of QCD radiative corrections to vector boson pair (VV) production in gluon fusion at LHC. VV production is, in general, of extreme phenomenological interest for understanding the electroweak sector of the Standard Model. Despite VV production occurs mainly through quark-antiquark annihilation, the gluon fusion channel provides a sizeable contribution, which was until recently known only through LO QCD. Radiative corrections to this channel are potentially very large and their computation requires a combination of state-of-the-art techniques.  I will focus on different technical details of the calculation, emphasising the physics implications of our results for the LHC.