Neutralino dark matter annihilation to monoenergetic gamma rays as a signal of low mass superstrings

TL;DR

This paper explores how low-mass superstring-inspired models predict observable gamma-ray lines from neutralino annihilation, offering a potential signal for dark matter detection.

Contribution

It introduces a supersymmetric model with R-symmetry violation allowing neutralino annihilation into gamma rays at detectable levels, differing from minimal models.

Findings

Neutralinos annihilate into gamma-gamma with ~10% branching ratio.

Predicted gamma-ray lines could be observable by telescopes.

Model consistent with observed dark matter relic abundance.

Abstract

We consider extensions of the standard model based on open strings ending on D-branes, in which gauge bosons and their associated gauginos exist as strings attached to stacks of D-branes, and chiral matter exists as strings stretching between intersecting D-branes. Under the assumptions that the fundamental string scale is in the TeV range and the theory is weakly coupled, we study models of supersymmetry for which signals of annihilating neutralino dark matter are observable. In particular, we construct a model with a supersymmetric R-symmetry violating (but R-parity conserving) effective Lagrangian that allows for the s-wave annihilation of neutralinos, once gauginos acquire mass through an unspecified mechanism. The model yields bino-like neutralinos (with the measured relic abundance) that annihilate to a gamma-gamma final state with a substantial branching fraction (~ 10%) that is orders of magnitude larger than in the minimal supersymmetric standard model. A very bright gamma-ray spectral line could be observed by gamma-ray telescopes.