Challenges for Hybrid inflation: SUSY GUTs, spectral index and initial conditions
Universite Libre de Bruxelles
Wed, Nov. 05th 2008, 14:15
Salle Claude Itzykson, Bât. 774, Orme des Merisiers
Now that CMB observational data increased in precision, the question of which (class of) models are the best candidates to realize inflation is particularly urging. Hybrid inflation is one of the three main classes of inflationary models and is considered very motivated among high energy physicists. After a quick review about hybrid inflation and the reasons why it is popular in the high energy community, I will discuss the phenomenology of these models and the challenges they have to face. I will first review some consequences of embedding it in SUSY GUTs such as the constraints imposed by the formation of cosmic strings. I will then turn to two of its main problems: the blue spectral index in disagreement with WMAP5 and the space of initial conditions for inflation to be successful. I will show that the slow roll approximation should not always be trusted to study the model, and discuss what we learn from the exact dynamics in terms of spectral index and ways to realize hybrid inflation. We have used numerical resolution of the dynamics to understand and study the properties of the initial condition space available for successful inflation. I will show that both problems mentioned above can be avoided by considering superplanckian initial values for the fields and discuss the consequences for the models.
Contact : mcirelli