August 28, 2011 to September 2, 2011
US/Central timezone
Slides available on Indico -- there are no formal proceedings

Dark radiation from the axino solution of the gravitino problem

Aug 29, 2011, 3:30 PM
B: Curia II, Wilson Hall 2SW (Universe)

B: Curia II, Wilson Hall 2SW


SUSY: phenomenology Parallel Session 4


Mr Jasper Hasenkamp (Hamburg U.)


Current CMB observations could confirm an increase of the effective neutrino degrees of freedom after primordial nucleosynthesis but before photon decoupling. We show that, if the gravitino problem is solved by a light axino, dark (decoupled) radiation emerges naturally in this period leading to a new upper bound on the reheating temperature < 10^10 GeV. In turn, successful thermal leptogenesis predicts such an increase. The LHC might endorse this opportunity. We identify several consistent cosmologies.


It is a absolutely new opportunity to determine the amount of radiation in the Universe from the CMB alone. Recent (first) publications of observations give mean values larger at the time of photon decoupling than at the time of primordial nucleosynthesis. As other explanaitions are missing we should search for explanaitions from particle physics. To our knowledge we provide the first possibility that is motivated from problems of the Standard Model and cosmology. We observe an astonishing coincidence for parameter values motivated by completely disconnected reasons. It is remarkable that we can obtain a consistent comology, e.g. also dark matter, at the same time.

Primary author

Mr Jasper Hasenkamp (Hamburg U.)

Presentation materials