Séminaire / Seminar GReCO |
| « Regularizing infrared divergences in de Sitter spacetime » |
|
Javier Huenupi |
| Scalar field correlation functions in de Sitter spacetimes, computed with standard perturbation theory, are hindered by time-dependent infrared divergences in the form of powers of ln a(t), where a(t) is the scale factor describing the expansion of space. It has been pointed out by several authors that loop corrections to these correlation functions make their divergences even stronger. In this talk, I will show that this is not the case: Loop corrections can be treated systematically with standard perturbative techniques (such as dimensional regularization) without necessarily introducing stronger ln a(t) dependences. To be concrete, we focus on correlation functions represented by diagrams with a single vertex and an arbitrary number of loops. In this case, divergences from loops can be removed systematically with counterterms order by order, and one finds that observable correlation functions, taking into account loop corrections, are indistinguishable from tree-level correlation functions. We further discuss how the validity of this statement should extend to other types of diagrams, with a larger number of vertices and loops. |
|
lundi 1 juillet 2024 - 11:00 Salle des séminaires Évry Schatzman Institut d'Astrophysique de Paris |
| Pages web du séminaire / Seminar's webpage |