EPT Seminar

Date
Thu, Jul 27, 2017 2:00 pm - 3:30 pm
Location
PSC 3150

Description

Speaker: Basudeb Dasgupta

Speaker Institution: Tata Institute of Fundamental Research

Title: Selection Rule for Enhanced Dark Matter Annihilation

Abstract: Growing interest in dark matter with interactions mediated by a light particle has brought renewed attention to ``Sommerfeld enhancement''. In the context of dark matter, this typically manifests as an increase in the annihilation cross-section when the dark matter particles collide at low velocities. I will show that, for two-level dark matter, this Sommerfeld enhancement can be selectively large for odd or even partial waves of the scattering amplitude. This odd vs. even selection owes its origin to the exchange symmetry of the colliding particles. As an application of this selection mechanism for phenomenology, I will outline a model of dark matter that predicts observably large p-wave annihilation rates only in galaxy-sizes halos, which explains why one may see its signal from nowhere else but the Milky Way.

Ref: A. Das and B. Dasgupta, Phys. Rev. Lett. 118 (2017) no.25, 251101