An Enhanced Cosmological Li6 Abundance as a Potential Signature of Residual Dark Matter Annihilations

TL;DR

This paper investigates how residual dark matter annihilations after Big Bang Nucleosynthesis could significantly increase the predicted abundance of Li6, providing a potential observational signature of dark matter properties.

Contribution

It demonstrates that residual dark matter annihilations can notably enhance Li6 abundance predictions in certain supersymmetric models, especially in the focus-point and coannihilation regions.

Findings

Negligible effects on Deuterium, He3, He4, and Li7 abundances.

Potential two-order magnitude increase in Li6 abundance in specific parameter regions.

Enhancement is insignificant in parts of the coannihilation strip consistent with LHC constraints.

Abstract

Residual late-time dark matter particle annihilations during and after Big Bang Nucleosynthesis (BBN) may alter the predicted cosmological abundances of the light elements. Within the constrained minimal supersymmetric extension of the Standard Model (the CMSSM) with a neutralino LSP, we find negligible effects on the abundances of Deuterium, He3, He4 and Li7 predicted by homogeneous BBN, but potentially a large enhancement in the predicted abundance of Li6. This enhancement may be as much as two orders of magnitude in the focus-point WMAP strip and in the coannihilation and funnel regions for large tan beta for small m_{1/2}, and the effect is still significant at large m_{1/2}. However, the potential Li6 enhancement is negligible in the part of the coannihilation strip for tan beta = 10 that survives the latest LHC constraints. A similar enhancement of the \li6 abundance may also be found in a model with common, non-universal Higgs masses (the NUHM1).