Center for Theoretical Physics of the Universe (CTPU)

# Dark Matter Sommerfeld-enhanced annihilation and bound-state decay at finite temperature

## by Dr. Tobias Binder (Kavli IPMU)

Wednesday, 26 June 2019 from to (Asia/Seoul)
at CTPU Seminar Room
Fourth floor IBS Building, 55, Expo-ro, Yuseong-gu, Daejeon, Korea, 34126
 Description Long-range interactions can lead to the existence of meta-stable bound-state solutions in the spectrum of WIMPs. During the last decade, it has been shown that the formation of these bound states and their subsequent decay into SM particles gives a significant effect in the relic density computation on top of the Sommerfeld enhancement, typically allowing for even heavier DM masses. In the first talk (introductory), an overview about the physics of quantum mechanical effects induced by long-range interactions is given (Sommerfeld enhancement, bound-state decay, bound-state formation and level transitions) and some model applications are discussed. I continue arguing that in some cases it might be not enough to consider a vacuum potential in the required solution of the two-body Schroedinger equation. Based on this, I introduce the Keldysh-Schwinger formalism as a mathematical tool for taking into account higher order corrections. In the second talk (main talk), I present our final result -- a rather general number density equation -- which allows to describe the DM chemical evolution including environmental effects like charge screening and Landau damping. It is shown that the latter two collective phenomena could lead to a melting or disappearance of the bound-state solutions, giving rise to non-trivial corrections in the relic density computation.    Material: Slides