Confronting the DAMPE Excess with the Scotogenic Type-II Seesaw Model

TL;DR

This paper proposes a scotogenic type-II seesaw model to explain the DAMPE cosmic-ray excess at 1.4 TeV, linking dark matter annihilation to neutrino mass generation and lepton signals.

Contribution

It introduces a novel extension of the type-II seesaw model incorporating dark matter and loop-induced triplet VEVs, providing a new explanation for the DAMPE excess.

Findings

DAMPE excess can be explained by dark matter annihilation into triplet scalars

Model favors inverted neutrino mass hierarchy based on spectrum fitting

Discusses how to avoid neutrino flux constraints in the model

Abstract

The DArk Matter Particle Explorer (DAMPE) has observed a tentative peak at $E\sim1.4~\TeV$ in the cosmic-ray electron spectrum. In this paper, we interpret this excess in the scotogenic type-II seesaw model. This model extends the canonical type-II seesaw model with dark matter (DM) candidates and a loop-induced vacuum expectation value of the triplet scalars, $v_\Delta$, resulting in small neutrino masses naturally even for TeV scale triplet scalars. Assuming a nearby DM subhalo, the DAMPE excess can be explained by DM annihilating into a pair of triplet scalars which subsequently decay to charged lepton final states. Spectrum fitting of the DAMPE excess indicates it potentially favors the inverted neutrino mass hierarchy. We also discuss how to evade associated neutrino flux in our model.