Directly Measuring the Tensor Structure of the Scalar Coupling to Gauge Bosons

TL;DR

This paper demonstrates that analyzing kinematic distributions in four-lepton decays can effectively determine the tensor structure of a scalar particle's couplings to gauge bosons, crucial for understanding its role in mass generation.

Contribution

It introduces a method to distinguish between Standard Model and higher-dimensional couplings to ZZ and Zγ using full event kinematics with relatively few signal events.

Findings

Discrimination between renormalizable and higher-dimensional couplings to ZZ at 95% confidence with ~50 events.

Coupling to Zγ can be distinguished with as few as 20 events.

Method applicable to current LHC data for probing scalar-gauge boson interactions.

Abstract

Kinematic distributions in the decays of the newly discovered resonance to four leptons can provide a direct measurement of the tensor structure of the particle's couplings to gauge bosons. Even if the particle is shown to be a parity even scalar, measuring this tensor structure is a necessary step in determining if this particle is responsible for giving mass to the Z. We consider a Standard Model like coupling as well as coupling via a dimension five operator to either ZZ or Z\gamma. We show that using full kinematic information from each event allows discrimination between renormalizable and higher dimensional coupling to ZZ at the 95% confidence level with O(50) signal events, and coupling to Z\gamma can be distinguished with as few as 20 signal events. This shows that these measurements can be useful even with this year's LHC data.