Taming the off-shell Higgs boson

TL;DR

This paper investigates off-shell Higgs production in proton collisions to constrain Higgs couplings, highlighting its potential to complement other measurements and exploring future collider prospects within an Effective Field Theory framework.

Contribution

It demonstrates the use of off-shell Higgs data to distinguish production contributions and assesses future collider capabilities for Higgs coupling measurements.

Findings

Current data cannot provide model-independent constraints.

Off-shell channel can help resolve gluon fusion contributions.

Future colliders could improve Higgs coupling measurements.

Abstract

We study the off-shell Higgs data in the process $pp\to h^{(*)} \to Z^{(\ast)}Z^{(\ast)}\to 4\ell$, to constrain deviations of the Higgs couplings. We point out that this channel can be used to resolve the long- and short-distance contributions to Higgs production by gluon fusion and can thus be complementary to $pp\to ht\bar t$ in measuring the top Yukawa coupling. Our analysis, performed in the context of Effective Field Theory, shows that current data do not allow one to draw any model-independent conclusions. We study the prospects at future hadron colliders, including the high-luminosity LHC and accelerators with higher-energy, up to 100 TeV. The available QCD calculations and the theoretical uncertainties affecting our analysis are also briefly discussed.