NLO QCD corrections to polarised di-boson production in semi-leptonic final states

Understanding the polarisation structure and providing precise predictions for multi-boson processes at the LHC is becoming urgent in the light of the upcoming run-3 and high-luminosity data. The CMS and ATLAS collaborations have already started using polarised predictions to perform template fits of the data, getting access to the polarisation of W and Z bosons. So far, only fully-leptonic decay channels have been considered in this perspective. The natural step forward is the investigation of hadronic decays of electroweak bosons. In this work, we compute NLO QCD corrections to the production and decay of WZ pairs at the LHC in final states with two charged leptons and jets. The calculation relies on the double-pole approximation and the separation of polarised states at the level of Standard Model amplitudes. The presented NLO-accurate results are necessary building blocks for a broad understanding and precise modelling of polarised di-boson production in semi-leptonic decay channels.Comment: 25 pages (one-column PRD layout), 12 figures, 3 tables. Refined structure, added comments and numbers about DPA accuracy and irreducible backgrounds, further minor corrections. Matches published version in PR

NLO QCD and EW corrections to off-shell tZj\mathrm{t}\mathrm{Z}\mathrm{j} production at the LHC

The production of a single top quark in association with a $\mathrm{Z}$ boson ($\mathrm{t}\mathrm{Z}\mathrm{j}$ production) at the LHC is a relevant probe of the electroweak sector of the Standard Model as well as a window to possible new-physics effects. The growing experimental interest in performing differential measurements for this process demands an improved theoretical modelling in realistic fiducial regions. In this article we present an NLO-accurate $\mathrm{t}\mathrm{Z}\mathrm{j}$ calculation that includes complete off-shell effects and spin correlations, combining QCD and electroweak radiative corrections to the LO signal. Integrated and differential cross-sections are shown for a fiducial setup characterized by three charged leptons, two jets, and missing energy.Comment: 24 pages, 10 figure

Complete NLO corrections to off-shell tt‾Z\text{t}\overline{\text{t}}\text{Z} production at the LHC

Measuring precisely top-pair-associated processes at hadron colliders will become possible with the upcoming LHC running stages. The increased data statistics will especially enable differential measurements leading to an improved characterisation of such processes. Aiming at a consistent data-theory comparison, precise Standard-Model predictions are needed, including higher-order corrections and full off-shell effects. In this work we present NLO-accurate predictions for the production and decay of a top-antitop pair in association with a Z boson at the LHC, in the multi-lepton decay channel. The complete set of LO contributions and NLO corrections of EW and QCD origin is included. The calculation is based on full matrix elements, computed with all resonant and non-resonant contributions, complete spin correlations and interference effects. Integrated and differential cross-sections are presented for a realistic fiducial setup.Comment: 38 pages, 10 pdf figure files, 24 png figure file

Different polarization definitions in same-sign WWWW scattering at the LHC

We study the polarization of positively charged $W$'s in the scattering of massive electroweak bosons at hadron colliders. We rely on the separation of weak boson polarizations in the gauge-invariant, doubly-resonant part of the amplitude in Monte Carlo simulations. Polarizations depend on the reference frame in which they are defined. We discuss the change in polarization fractions and in kinematic distributions arising from defining polarization vectors in two different reference frames which have been employed in recent experimental analyses.Comment: added reference to CMS measurement, typos corrected, matches PLB published versio

NLO EW corrections to polarised W+^+W−^- production and decay at the LHC

In this letter we present results for next-to-leading-order electroweak corrections to doubly polarised W$^+$W$^-$ production at the LHC in the fully leptonic decay channel. We model the production and the decay of two polarised W bosons in the double-pole approximation, including factorisable real and virtual electroweak corrections, and separating polarisation states at amplitude level. We obtain integrated and differential predictions for polarised signals in a realistic fiducial setup.Comment: 10 pages, 1 table, 4 figure

Factorisation and Subtraction beyond NLO

We provide a general method to construct local infrared subtraction counterterms for unresolved radiative contributions to differential cross sections, to any order in perturbation theory. We start from the factorised structure of virtual corrections to scattering amplitudes, where soft and collinear divergences are organised in gauge-invariant matrix elements of fields and Wilson lines, and we define radiative eikonal form factors and jet functions which are fully differential in the radiation phase space, and can be shown to cancel virtual poles upon integration by using completeness relations and general theorems on the cancellation of infrared singularities. Our method reproduces known results at NLO and NNLO, and yields substantial simplifications in the organisation of the subtraction procedure, which will help in the construction of efficient subtraction algorithms at higher orders.Comment: 34 pages, 3 figure