Azimuthal asymmetries in hard scattering processes

by Massimiliano Grazzini (Universitaet Zuerich (CH))

Thursday 16 May 2019, 13:30 → 14:30 Europe/Zurich

Edificio U2, Aula 5017 (Dipartimento di Fisica G. Occhialini, U2, Università degli Studi di Milano-Bicocca)

We consider high-mass systems of two or more particles that are produced by QCD hard scattering in hadronic collisions. We point out that there is a class of azimuthal observables that exibit infrared divergences when computed at fixed perturbative order. Examples of processes with fixed-order divergences are heavy-quark pair production, associated production of vector bosons and jets, dijet and diboson production. We discuss the physical origin of the divergences and we show lowest-order illustrative results for azimuthal asymmetries in top-quark pair production and associated production of a vector boson and a jet at the LHC. The divergences are removed by a proper all-order resummation procedure of the perturbative contributions. Resummation leads to azimuthal asymmetries that are finite and computable.

Grazzini_Bicocca.pdf