Daniele Lombardi

A bstract: We present the first calculation of the next-to-leading-order electroweak corrections to vector-boson scattering into doubly polarised Z bosons at the LHC in the fully leptonic decay channel. The production and decay of the two polarised Z bosons are consistently modelled in the double-pole approximation, separating polarisation states at the amplitude level and including factorisable real and virtual electroweak corrections. Doubly polarised and unpolarised signals are investigated and confronted with off-shell results. A broad analysis, including results at integrated and differential level, is carried out in a realistic, CMS-inspired fiducial setup. Our study paves the way to upcoming analyses with LHC Run-3 and High-Luminosity data as well as to further phenomenological investigations.

We present the Monte Carlo integration code MoCaNLO, which computes cross sections and distributions for processes at high-energy colliders like the LHC at leading and next-to-leading order (NLO) in the strong and electroweak couplings. It relies on the Recola package for the calculation of matrix elements and uses Catani–Seymour dipole subtraction for the treatment of infrared singularities. It has been used for several cutting-edge calculations of NLO QCD and electroweak corrections over the last years, such as NLO QCD corrections to off-shell top–antitop-quark production in association with a pair of bottom quarks and NLO electroweak corrections to vector-boson scattering processes.

A bstract: We present full off-shell NLO corrections in QCD obtained with the M o C a NLO code matched to parton shower. A resonance-aware matching procedure has been devised for the MC@NLO method tuned to the Catani-Seymour dipole subtraction. Specifically, we consider the off-shell production of a top–antitop pair in the semi-leptonic decay channel in electron–positron collisions and match it to the final-state QCD parton shower of P ythia 8. Distortions of resonances’ line shapes are avoided by providing the details of the resonance-cascade chain on an event-by-event basis to the parton shower and by adapting the matching accordingly through the introduction of dedicated counterterms.

A bstract: We present a calculation of next-to-leading-order electroweak corrections to the vector-boson scattering (VBS) process resulting in leptonically decaying W and Z bosons in association with two jets at the LHC. The VBS process is computed for both polarised and unpolarised intermediate bosons, exploiting the pole approximation and the separation of helicity states in tree-level and one-loop amplitudes. A phenomenological analysis is carried out for a realistic fiducial setup at a 13.6 TeV LHC collision energy, highlighting different patterns for the various polarisation states both at integrated and at differential level. This study provides theoretical predictions that are necessary to perform a sound characterisation of the spin structure of VBS processes with full LHC data.

We present predictions for the production and decay of a top–antitop pair in association with a \rm Z boson in the multi-lepton decay channel at the LHC. Our results include the complete set of LO and NLO contributions. Since our calculation is based on full matrix elements, off-shell effects are entirely taken into account. Integrated and differential cross-sections are reported for a realistic fiducial setup.

In this contribution we review the status of theory results for top-pair production at the LHC in association with a heavy boson. Our focus is to illustrate the impact of off-shell effects and electroweak corrections. We show that their inclusion is indispensible for predictions aiming at the percent accuracy not just for the integrated cross section, but also for more differential observables.

We present a calculation of next-to-leading-order electroweak corrections to the vector-boson scattering (VBS) process resulting in leptonically decaying W and Z bosons in association with two jets at the LHC. The VBS process is computed for both polarised and unpolarised intermediate bosons, exploiting the pole approximation and the separation of helicity states in tree-level and one-loop amplitudes. A phenomenological analysis is carried out for a realistic fiducial setup at a 13.6 TeV LHC collision energy, highlighting different patterns for the various polarisation states both at integrated and at differential level. This study provides theoretical predictions that are necessary to perform a sound characterisation of the spin structure of VBS processes with full LHC data.