The 30 GeV Dimuon Excess at ALEPH

TL;DR

This paper proposes a variation of a two-Higgs-doublet model to explain a 30 GeV dimuon excess observed in ALEPH data, offering two scenarios and discussing testable predictions and theoretical constraints.

Contribution

It introduces a specific two-Higgs-doublet model variation that accounts for the 30 GeV dimuon excess and analyzes its implications and testability.

Findings

ALEPH data favor the scenario with degenerate light Higgs and pseudoscalar states.

The model provides testable predictions for LHC and LEP experiments.

Discussion of a potential no-go theorem constraining such models.

Abstract

A simple variation of a two-Higgs-doublet model is proposed to describe the $30\,{\rm GeV}$ dimuon excess reported by Heister in his reanalysis of $Z \to \bar bb$ events in ALEPH data taken in 1992-95. The heavier CP-even Higgs $H$ is the $125\,{\rm GeV}$ Higgs boson discovered at the LHC. The model admits two options for describing the dimuon excess: (1) The lighter CP-even Higgs $h$ and the CP-odd state $\eta_A$ are approximately degenerate and contribute to the $30\,{\rm GeV}$ excess. (2) Only the $h$ is at $30\,{\rm GeV}$ while the $\eta_A$ and $H$ are approximately degenerate at $125\,{\rm GeV}$. The ALEPH data favor option 1. Testable predictions are presented for LHC as well as LEP experiments. A potential no-go theorem for models of this type is also discussed.