Theory seminar: Luca Buonocore: Associated production of a heavy quark pair and a heavy boson in next-to-next leading order QCD


We focus on the associated production of a heavy quark pair and a W boson and review recent developments in the calculation of the second order radiative corrections in the strong interaction. In the case the heavy quark is the relatively light bottom quark, the Wbb process represents one of the main background to the associated production of a Higgs and a W boson, with the Higgs decaying into a bottom-antibottom pair. From a theoretical perspective, the inclusion of mass effects is particularly interesting in the context of flavor jets. Indeed, the use of massive quarks avoids the ambiguities associated with the correct flavor assignment in massless calculations.

In the case the heavy quark is the top quark, the Wtt system represents one of the heaviest signatures currently probed at the Large Hadron Collider. The corresponding measured rates are consistently higher than the Standard Model predictions, based on next-to-leading order calculations in the QCD and electroweak interactions, thereby motivating the effort of computing the NNLO QCD correction. We have completed the calculation of this correction by estimating the corresponding two-loop virtual amplitude, which is still not available, using two different approaches that lead to consistent results within their uncertainties. We found that the inclusion of the NNLO QCD correction slightly alleviates the tension with the latest ATLAS and CMS results, which remains at the 1-2 sigma level.

Organized by

Ankita Budhraja, Juraj Klaric, Johannes Michel, Tanjona R. Rabemananjara