γ rays from in-flight positron annihilation as a probe of new physics

2024/05/14 by Pedro De la Torre Luque, S. Balaji, Luque, Pedro De la Torre +5 · 3 citations
Physics and Astronomy · #Dark Matter and Cosmic Phenomena #Radiation Detection and Scintillator Technologies #Radioactive Decay and Measurement Techniques

paper · pdf · doi:10.48550/arxiv.2405.08482

Abstract

The γ ray emission originating from in-flight annihilation (IA) of positrons is a powerful observable for constraining high-energy positron production from exotic sources. By comparing diffuse γ ray observations of INTEGRAL, COMPTEL and EGRET to theoretical predictions, we set the most stringent constraints on electrophilic feebly interacting particles (FIPs), thereby proving IA as a valuable probe of new physics. In particular, we extensively discuss the case of MeV-scale sterile neutrinos, where IA sets the most stringent constraints, excluding |U_μ4|² \gtrsim 10^-13 and |U_τ4|² \gtrsim 2× 10^-13 for sterile neutrinos mixed with μ and τ neutrinos respectively. These constraints improve existing limits by more than an order of magnitude. We briefly discuss the application of these results to a host of exotic positron sources such as dark photons, axion-like particles, primordial black holes (PBHs) and sub-GeV dark matter (DM).

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