A tale of two Higgs

TL;DR

This paper investigates whether the observed 125 GeV boson signals in different channels could be due to two distinct resonances within extended Higgs models, finding specific scenarios where this is possible and predicting future experimental deviations.

Contribution

It demonstrates that a two-resonance explanation for the Higgs signals is generally not feasible in pure 2HDM but can occur with additional scalars, providing testable predictions for future experiments.

Findings

Two-resonance scenario is not possible in pure 2HDM.

Adding top-like scalars allows for two distinct resonances.

Future deviations in decay rates can help exclude the two-resonance hypothesis.

Abstract

A new boson with mass ~125 GeV and properties similar to the Standard Model Higgs has been discovered by both the ATLAS and CMS collaborations, with significant observation in the ZZ* to 4 leptons and the diphoton channels. In this work we ask whether the signals in these two channels can be due primarily to two distinct resonances, each contributing dominantly to one channel. We investigate this question in the framework of a 2HDM and several of its extensions. We conservatively find that such a scenario is not possible in a pure 2HDM, nor under the addition of vector-like quarks, but is allowed when adding one or two top-like scalars, if one allows for sub-one tan\beta. The resonances in the diboson and diphoton channels can then be two scalars, or a scalar and a pseudoscalar, respectively. In each viable case, we further find the expected future deviations in the diboson, diphoton, b \bar b and tau tau rates, which will be useful in excluding the two-resonance scenario.