Automated predictions from polarized matrix elements

Abstract

Abstract The anticipated experimental resolution and data cache of the High Luminosity Large Hadron Collider will enable precision investigations of polarization in multiboson processes. This includes, for the first time, vector boson scattering. To facilitate such studies, we report the automation of polarized matrix element computations in the publicly available Monte Carlo tool suite, MadGraph5_aMC@NLO. This enables scattering and decay simulations involving helicity-polarized asymptotic or intermediate states, preserving both spin-correlation and off-shell effects. As demonstrations of the method, we investigate the leading order production and decay of polarized weak gauge bosons in the process pp → jjW λ + W λ ′ − $$ pp\to {jjW}_{\lambda}^{+}{W}_{\lambda \prime}^{-} $$ , with helicity eigenstates (λ, λ′) defined in various reference frames. We consider the Standard Model at both O $$ \mathcal{O} $$ (α 4) and O $$ \mathcal{O} $$ (α 2 α s 2 $$ {\alpha}_s^2 $$ ) as well as a benchmark composite Higgs scenario. We report good agreement with polarization studies based on the On-Shell Projection (OSP) technique. Future capabilities are discussed.

Keywords

• Polarization
• Electroweak interaction
• Hadron-Hadron scattering (experiments)
• Beyond Standard Model
• Top physics