Single-variable asymmetries for measuring the `Higgs' boson spin and CP properties

TL;DR

This paper proposes a set of asymmetries in four-lepton decays to determine the Higgs boson's spin and CP properties, providing a practical method for analyzing LHC data to uncover its quantum nature.

Contribution

It introduces novel asymmetries based on invariant mass integrations to measure the Higgs boson's spin and CP characteristics using LHC data.

Findings

Disfavoring certain spin-2 coupling models with current data

Method to distinguish CP-odd from CP-even Higgs states

Analytic expressions for decay widths in various models

Abstract

We introduce a class of asymmetries sensitive to the spin and CP properties of the new boson discovered by the ATLAS and CMS experiments. These asymmetries can be measured in the four-lepton final state, and are defined by integrating the invariant masses of the lepton pairs over specified ranges. We outline a program of measurements using initial LHC data to determine the quantum numbers and coupling structure, provide analytic expressions for decay widths in several representative models, and discuss what can be determined using the available data. As examples, we show how the combination of ATLAS and CMS data already disfavor certain spin-2 couplings, and discuss how further data will allow for discrimination of a pure CP-odd scalar from a CP-even hypothesis.