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: 45′ + 15′ for questions
Contact: Sofie Marie Koksbang
(See the updated page at www.hip.fi/cosmoseminars)
- 12.02.2020 Dimitrios Karamitros (NCBJ, Warsaw)
Title: Recalculating freeze-in
Abstract: The freeze-in mechanism has become very popular recently, due to its ability to explain the dark matter relic abundance with suppressed couplings, and thus (usually) evading all experimental constraints. However, the production of dark matter often is not treated carefully, and so some aspects of frozen-in relics are not pointed-out. In this talk, I will try to summarize some of the ways freeze-in can be different than one expects. In sort, I will show as generally as possible the effects of thermal masses, quantum statistics, and potential non-standard cosmological expansion on freeze-in.
- 04.03.2020 Valentina De Romeri (IFIC)
Title: Searches for new physics with neutrino experiments
Abstract: In this talk I will discuss the possibility of unveiling new physics with neutrino experiments. I will focus on two different cases. In the first part of the talk I will use the recent observation of coherent elastic neutrino-nucleus scattering (CEvNS) to probe neutrino generalised interactions. Then, I will investigate opportunities for detecting light dark matter at DUNE, a next generation long baseline neutrino experiment.
- 18.03.2020 Mindaugas Karciauskas (Complutense, Madrid)
Title: Quintessential inflation with a trap and axionic dark matter
Abstract: We study a new model of quintessential inflation which is inspired by supergravity and string theory. The model features a kinetic pole, which gives rise to the inflationary plateau, and a runaway quintessential tail. We envisage a coupling between the inflaton and the Peccei-Quinn (PQ) field which terminates the roll of the runaway inflaton and traps the latter at an enhanced symmetry point (ESP), thereby breaking the PQ symmetry. The kinetic density of the inflaton is transferred to the newly created thermal bath of the hot big bang due to the decay of PQ particles. The model successfully accounts for the observations of inflation and dark energy with natural values of the model parameters, while also resolving the strong CP problem of QCD and generating axionic dark matter, without isocurvature perturbations. Trapping the inflaton at the ESP ensures that the model does not suffer from the infamous 5th force problem, which typically plagues quintessence.
- 19.03.2020 Mairi Sakellariadou (King’s Coll. London)
Note: THURSDAY in Physicum E206 at 14:14
Title: Gravitational Waves: the theorist’s swiss knife
Abstract: After a short introduction to the stochastic GW background I will highlight how one uses currently available LIGO/Virgo data not only to learn about compact binaries and the large-scale-structure of our universe, but also to constrain particle physics models beyond the Standard Model, modified gravity proposals, and even quantum gravity theories.
- 25.03.2020 Amel Durakovic (Technical University of Denmark and NBI)
Title: A Map Between Primordial Power Spectra and the Effective Field Theory of Inflation
Abstract: We have developed a precise dictionary between the spectrum of primordial density fluctuations and the parameters of the effective field theory (EFT) of inflation that determine the primordial power spectrum (PPS). At lowest order the EFT contains two parameters: the slow-roll parameter, which acts as an order parameter, and the speed of sound. Applying second-order perturbation theory, we provide maps from the PPS to the EFT parameters that are precise up to the cube of the fractional change in the PPS, or less than 1% for spectral features that modulate the PPS by 20%. While such features are not required when the underlying cosmological model is assumed to be ΛCDM they are necessary for alternative models that have no cosmological constant/dark energy. We verify the dictionary numerically and find those excursions in the slow-roll parameter that reproduce the PPS needed to fit Planck data for cosmological models with and without a cosmological constant.
- 01.04.2020 Jonathan Gair (Max Planck Institute)
- 15.04.2020 Daniel Litim (University of Sussex)
- 22.04.2020 Saul Ramos-Sanchez (Technical University Munich and UNAM, Mexico)
- 06.05.2020 Giorgio Arcadi (Universita di Roma 3)
- 13.05.2020 Marco Drewes (Louvain U., CP3)
- 20.05.2020 Anastasiia Filimonova (Heidelberg University)
- 11.11.2020 Hayley Macpherson (University of Cambridge).