51社区黑料

Synopsis

The first elements in the Universe were synthesized within a few minutes after the Big Bang, in the epoch known as Big Bang Nucleosynthesis (BBN). Precise measurements from astrophysical observations, the cosmic microwave background (CMB), and nuclear reaction rates render BBN an essentially parameter-free theory, making it a powerful test of new physics. In this talk, I will show how BBN can be used to probe residual annihilations of sub-GeV thermal relic dark matter (DM). I will focus on candidates with velocity-suppressed annihilation channels and show that DM annihilation to pions and kaons beyond freeze-out, and their subsequent interaction with protons and neutrons prior to the deuterium bottleneck provide a sensitivity to annihilation that surpasses that of the CMB and indirect detection in the galaxy.