Antiproton Limits on Decaying Gravitino Dark Matter

TL;DR

This paper establishes the most stringent constraints to date on the lifetime of decaying gravitino dark matter using cosmic-ray antiproton data from PAMELA, covering masses from 100 GeV to 10 TeV.

Contribution

It provides new, robust lower limits on gravitino lifetime based on antiproton observations, surpassing previous gamma-ray and neutrino constraints.

Findings

Lower limits on gravitino lifetime range from 8×10^{28} s to 6×10^{28} s.

Antiproton limits are the strongest among current observational constraints.

Constraints imply upper limits on R-parity breaking parameter between 10^{-8} and 8×10^{-13}.

Abstract

We report on constraints on the lifetime of decaying gravitino dark matter in models with bilinear R-parity violation derived from observations of cosmic-ray antiprotons with the PAMELA experiment. Performing a scan over a viable set of cosmic-ray propagation parameters we find lower limits ranging from $8\times 10^{28}$s to $6\times 10^{28}$s for gravitino masses from roughly 100 GeV to 10 TeV. Comparing these limits to constraints derived from gamma-ray and neutrino observations we conclude that the presented antiproton limits are currently the strongest and most robust limits on the gravitino lifetime in the considered mass range. These constraints correspond to upper limits on the size of the bilinear R-parity breaking parameter in the range of $10^{-8}$ to $8\times 10^{-13}$.