From angular coefficients to quantum observables: a phenomenological appraisal in di-boson systems

TL;DR

This paper investigates how to accurately measure quantum entanglement and Bell-inequality violations in di-boson systems at the LHC, emphasizing the importance of higher-order corrections and realistic effects for proper interpretation.

Contribution

It provides a detailed phenomenological analysis highlighting the necessity of including higher-order corrections and realistic effects in the study of quantum properties of di-boson systems.

Findings

Higher-order QCD and electroweak corrections are essential.

Realistic effects like fiducial cuts impact measurements.

Analysis applies to boson pairs from Higgs decays and electroweak production.

Abstract

Motivated by the growing interest in accessing the spin structure of multi-boson processes and in measuring quantum entanglement at high energies, we study polarisation and spin-correlation coefficients in di-boson systems. We show that higher-order corrections of QCD and electroweak type, off-shell modelling, and realistic effects such as fiducial selections and neutrino reconstruction are unavoidable to properly determine such coefficients, and consequently to provide a sound interpretation of observables sensitive to quantum entanglement and Bell-inequality violation. Our findings are based on a detailed phenomenological analysis of boson pairs at the LHC, either in inclusive electroweak production or coming from Higgs-boson decays.