Speaker
Description
If the mediator in a given $2\to 2$ $t$-channel process is kinematically allowed to be on-mass-shell, the matrix element can become singular. For a massive and stable mediator, this singularity cannot be regularized using the usual methods, like Dyson resummation of self-energy contributions, or infra-red regularization schemes.
Models of particle dark matter are especially affected by this issue, as they by definition propose new massive stable particles. The singularity makes the relevant Boltzmanne quations impossible to solve.
In this talk, I will formulate a strict set of conditions for a given process to provide a singular contribution to the relevant Boltzmann equation. I will also describe the regularizatin method including interactions between the mediator and the surrounding medium, developed within the framework of thermal field theory. An application to an actual DM model will be presented.
| Submitted on behalf of a Collaboration? | No |
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