PAMELA's cosmic positron from decaying LSP in SO(10) SUSY GUT

TL;DR

This paper proposes two models within supersymmetric grand unified theories to explain the cosmic positron excess, involving either multi-component dark matter or specific R-parity violation mechanisms.

Contribution

It introduces two novel scenarios—one with multi-component dark matter and another based on SO(10) SUSY GUT—to account for cosmic positron observations.

Findings

Small non-thermal dark matter component explains positron excess.

Natural R-parity violation in SO(10) model enables LSP decay to e^ extpm.

Both scenarios are consistent with relic density constraints.

Abstract

We propose two viable scenarios explaining the recent observations on cosmic positron excess. In both scenarios, the present relic density in the Universe is assumed to be still supported by thermally produced WIMP or LSP (\chi). One of the scenarios is based on two dark matter (DM) components (\chi,X) scenario, and the other is on SO(10) SUSY GUT. In the two DM components scenario, extremely small amount of non-thermally produced meta-stable DM component [O(10^{-10}) < n_X /n_\chi] explains the cosmic positron excess. In the SO(10) model, extremely small R-parity violation for LSP decay to e^\pm is naturally achieved with a non-zero VEV of the superpartner of one right-handed neutrino (\tilde{\nu}^c) and a global symmetry.