Primordial black holes and lepton flavor violation with scotogenic dark matter

TL;DR

This paper explores how observing lepton flavor violation in muon decays can constrain the initial density of primordial black holes within the scotogenic dark matter framework, linking particle physics and early universe cosmology.

Contribution

It establishes a novel connection between lepton flavor violation signals and primordial black hole density constraints in the context of the scotogenic dark matter model.

Findings

PBH initial density constrained to $2\times 10^{-17}$ to $3\times 10^{-16}$ in radiation era.

PBH initial density constrained to $1\times 10^{-8}$ to $3\times 10^{-7}$ in PBH dominated era.

Constraints depend on dark matter mass scale and era of PBH evaporation.

Abstract

We show that if the lepton flavor violating $\mu \rightarrow e \gamma$ process is observed in the MEG II experiment, the initial density of primordial black holes (PBHs) can be constrained with the scotogenic dark matter. As a benchmark case, if the PBH evaporation occurs in the radiation dominated era, the initial density may be $2\times 10^{-17} \lesssim \beta \lesssim 3 \times 10^{-16}$ for $\mathcal{O}$ (TeV) scale dark sector in the scotogenic model where $\beta=\rho_{\rm PBH}/\rho_{\rm rad}$ is the ratio of the PBH density $\rho_{\rm PBH}$ to the radiation density $\rho_{\rm rad}$ at the time of PBH formation. As an other benchmark case, if PBHs evaporate in the PBH dominated era, the initial density may be $1 \times 10^{-8} \lesssim \beta \lesssim 3 \times 10^{-7}$ for $\mathcal{O}$ (GeV) scale dark matter with other $\mathcal{O}$ (TeV) scale particles in the scotogenic model.