| DATE: |
2012-07-10 11:00 - 12:00 |
| PLACE: |
Kenkyu Honkan 1F, Meeting Room 1 |
| TITLE: |
Boltzmann equation for non-equilibrium particles and its application to non-thermal dark matter production |
| CONTACT: |
Keiko Nagao, knagao-AT-post.kek.jp |
| SPEAKER: |
Dr. Kyohei Mukaida (Tokyo Universtity ) |
| LANGUAGE: |
English |
| URL: |
http://theory-center.kek.jp/theory/archives/s_c/seminar |
| ABSTRACT: |
We consider a scalar field which is very weakly interacting with the thermal bath, and study thermal effects on the evolution of its number density. We use the Boltzmann equation derived from the Kadanoff-Baym equation, assuming that the degrees of freedom in the thermal bath are well described as ``quasi-particles'' with thermally modified dispersion relations. The obtained Boltzmann equation differs from the conventional one since the collision term is thermally modified through ``quasi-particles.'' Then, we apply this equation to the Freeze-In dark matter production scenario. We show that thermal effects can change the resultant dark matter abundance by ${cal O} (10-100) %$ compared to the result without taking account of thermal effects. |
