Learning what the Higgs boson is mixed with

TL;DR

This paper proposes a method to determine the electroweak quantum numbers of a potential additional scalar mixed with the Higgs boson by measuring specific couplings through double Higgs production in electron-positron collisions.

Contribution

It introduces a novel approach to identify the electroweak properties of a mixed scalar by analyzing double Higgs production at different energies.

Findings

Simultaneous sensitivity to quartic and triple Higgs couplings is achievable.

Kinematic distributions can enhance discrimination of scalar properties.

Method applies to future e+e- collider measurements.

Abstract

The Standard Model Higgs boson may be mixed with another scalar that does not couple to fermions. The electroweak quantum numbers of such an additional scalar can be determined by measuring the quartic Higgs-Higgs-vector-vector couplings, which contribute---along with the coveted triple Higgs coupling---to double Higgs production in $e^+e^-$ collisions. We show that simultaneous sensitivity to the quartic Higgs-Higgs-vector-vector coupling and the triple Higgs coupling can be obtained using measurements of the double Higgs production cross section at two different e+e- center-of-mass energies. Kinematic distributions of the two Higgs bosons in the final state could provide additional discriminating power.