We have weekly seminars dedicated to Cosmology and Astroparticle Physics (we also have other regular weekly meetings to discuss the latest results in our field). Former presentations are available from the past cosmology seminars pages. Please write to the contact below to join the mailing list.
Time: Wednesdays 14:15-15:15, during term time.
Place: room A315 (3rd floor of the Physicum building)
Format: 50′ + 10′ for questions
Contact: Francesco Montanari
- 23.05.2018 Javier Rubio (U. Heidelberg, ITP)
Higgs-Dilaton Cosmology: An inflation–dark-energy connection.
Abstract: Inflation and dark energy share many essential properties. I will describe how these two eras can be easily unified into a common framework based on scale invariance. In particular, I will present a scale-invariant extension of the Standard Model non-minimally coupled to gravity containing just an additional degree of freedom on top of the Standard Model particle content. This model has some interesting features such as i) the existence of a conserved current that effectively forbids the generation of isocurvature perturbations ii) an alpha-attractor solution for the spectral tilt and the tensor-to-scalar ratio, iii) the absence of fifth-force effects and iv) a set measurable consistency relations between the inflationary observables and the dark-energy equation-of-state parameter that can be tested with future cosmological observations.
- 06.06.2018 Neil Barrie (IPMU)
Abstract: We propose a new non-thermal Leptogenesis mechanism that takes place during the reheating epoch, utilising the Ratchet mechanism. The interplay between the oscillation of the inflaton during reheating and a scalar lepton leads to a dynamical system that emulates the well-known forced pendulum. This is found to produce driven motion in the phase of the scalar lepton which leads to the generation of a non-zero lepton number density that is later redistributed to baryon number via sphaleron processes. This model successfully reproduces the observed baryon asymmetry, while simultaneously providing an origin for neutrino masses via the seesaw mechanism.
- 29.08.2018 Toyokazu Sekiguchi (University of Tokyo)