Invisible decays of axion-like particles: constraints and prospects

Luc Darmé,Federica Giacchino,Mauro Raggi,Enrico Nardi

doi:10.1007/jhep06(2021)009

Abstract

Axion-like particles (ALPs) can provide a portal to new states of a dark sector. We study the phenomenology of this portal when the ALP mainly decays invisibly, while its interaction with the standard model sector proceeds essentially via its coupling to electrons and/or photons. We reanalyse existing limits from various collider and beam dump experiments, including in particular ALP production via electron/positron interactions, in addition to the usual production through ALP-photon coupling. We further discuss the interplay between these limits and the intriguing possibility of explaining simultaneously the muon and electron magnetic moment anomalies. Finally, we illustrate the prospects of ALP searches at the LNF positron fixed-target experiment PADME, and the future reach of an upgraded experimental setup.

Highlights

IntroductionIn this work we explore the possibility that an Axion-like particles (ALPs) acts as a portal towards a dark sector containing other invisible and light SM gauge singlets
Generally, light particles presenting the same types of derivative interactions are motivated by various BSM theoretical scenarios, such as string theory [8, 9], or by extensions to the SM designed to address specific SM issues such as the strong-CP problem [10, 11] or the hierarchy problem [12]
In this work we have presented a thorough analysis of the experimental constraints on the scenario in which an Axion-like particles (ALPs) constitutes a portal to a dark sector, and dominantly decays into light dark particles, while in the SM sector it couples to photons and electrons to which it can decay, but with subdominant branching ratios

Summary

Introduction

In this work we explore the possibility that an ALP acts as a portal towards a dark sector containing other invisible and light SM gauge singlets Searches for such light and feebly interacting new particles can be carried out in experiments which trade a large energy scale for an increase in statistics and reduction in backgrounds [37, 38]. These so-called “high-intensity frontier” experiments have attracted a strong interest in recent years.

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Conclusion