Signatures of long-lived exotic strongly interacting massive particles on light element abundances through reactions triggered by the particles

Abstract

A primordial 7Li abundance inferred from observations of metal-poor halo stars is a factor of about three smaller than predictions of standard big bang nucleosynthesis (BBN) model. Some particle models beyond the standard model include heavy long-lived colored particles with mass much larger than 1 GeV. They would be confined inside exotic heavy hadrons, i.e., strongly interacting massive particles. We have found possible reactions which destroy 7Be and 7Li in the scenario of BBN including a long-lived sub-strongly interacting massive particle (sub-SIMP, X). The destruction is associated with non radiative X captures of the nuclei, and it can be realized only if the interaction strength between an X and a nucleon is properly weaker than that between two nucleons. Binding energies of nuclei to an X and nuclear reaction rates associated with the X are estimated. We perform a network BBN calculation using the estimated rates, and suggest that the 7Li problem can be solved if long-lived sub-SIMPs have existed.