Dark matter annihilation via dark bound state formation

Abstract:

We study the effect of dark matter bound state formation by emitting a light mediator on dark matter indirect detections. We found that dark matter annihilation inside the bound states can play an important role in enhancing signal rates over the rate for direct dark matter annihilation with Sommerfeld enhancement. We also show that in p-wave annihilation models with a light mediator, there can be s-wave channels for dark matter to form bound state, which will strongly enhance the annihilation rate of dark matter during the recombination era and yield a strong CMB constraint.