In-flight positron annihilation as a probe of feebly interacting particles

TL;DR

This paper uses supernova-produced positron annihilation signals to set new, more stringent bounds on feebly interacting particles like ALPs, sterile neutrinos, and dark photons, improving our understanding of their properties.

Contribution

It introduces a novel method of constraining heavy FIPs by analyzing in-flight positron annihilation signals from supernovae using gamma-ray data.

Findings

Derived the most stringent bounds on FIP-electron couplings.

Strengthened existing bounds by one or two orders of magnitude.

Utilized gamma-ray data from COMPTEL and EGRET.

Abstract

Core-collapse supernovae (SNe) provide a unique environment to study Feebly Interacting Particles (FIPs) such as Axion-Like Particles (ALPs), sterile neutrinos, and Dark Photons (DPs). This paper focuses on heavy FIPs produced in SNe, whose decay produces electrons and positrons, generating observable secondary signals during their propagation and annihilation. We focus on the In-flight Annihilation (IA) of positrons, which emerge as the most significant contribution to the resulting gamma-ray spectrum. Using data from COMPTEL and EGRET we derive the most stringent bounds on the FIP-electron couplings for heavy ALPs, sterile neutrinos, and DPs. These results strenghten existing bounds of one or two orders of magnitude, depending on the FIP model.