Seminarium "High Energy, Cosmology and Astro-particle physics (HECA)"
2020/2021 | 2021/2022 | 2022/2023 | 2023/2024 | 2024/2025 | Strona własna seminarium
2025-11-04 (Wtorek)
Zapraszamy do sali B2.38, ul. Pasteura 5 o godzinie 11:15 
Yue-Lin Sming Tsai (Purple Mountain Observatory, Chinese Academy of Sciences)Searching for Non-Gravitational Signals of Dark Matter: The Particle Nature of Dark Matter
The simplest dark matter models are those in which dark matter candidates annihilate via s-wave interactions during the thermal equilibrium process in the early universe. However, particle collider experiments and direct detection experiments have yet to yield decisive results. For dark matter candidates with masses ranging from MeV to 10 TeV, satisfying the conditions of early universe thermal equilibrium requires annihilation processes with velocity dependencies. In this talk, I will explore how indirect detection methods and cosmological observations can be used to search for such non-s-wave annihilating dark matter candidates.
2025-11-03 (Poniedziałek)
Zapraszamy do sali B2.38, ul. Pasteura 5 o godzinie 11:15
Kensuke Akita (University of Tokyo)Maximal parameter space of sterile neutrino dark matter with lepton asymmetries
Note unusual day!!!
Large lepton flavor asymmetries with zero total lepton asymmetry could be generated in the Early Universe. They are loosely constrained by current observations, being washed out at MeV temperatures by neutrino oscillations. We show that such lepton flavor asymmetries open up a new parameter space for sterile neutrino dark matter, consistent with all observational bounds. To this end, we construct the semi-classical Boltzmann equation for sterile neutrinos applicable in the case of arbitrarily large lepton asymmetries, and confirm its validity by quantum kinetic equations. This way, we derive the maximal parameter space for sterile neutrino dark matter with lepton asymmetries. The allowed range of sterile neutrinos' squared couplings extends by up to two orders of magnitude across a 5-60 keV mass range, and may be testable by X-ray, structure formation, and upcoming CMB observations. We will also discuss the origin of lepton flavor asymmetries: leptoflavorgenesis, and the recently reported helium-4 anomaly in the Universe associated with it.
Large lepton flavor asymmetries with zero total lepton asymmetry could be generated in the Early Universe. They are loosely constrained by current observations, being washed out at MeV temperatures by neutrino oscillations. We show that such lepton flavor asymmetries open up a new parameter space for sterile neutrino dark matter, consistent with all observational bounds. To this end, we construct the semi-classical Boltzmann equation for sterile neutrinos applicable in the case of arbitrarily large lepton asymmetries, and confirm its validity by quantum kinetic equations. This way, we derive the maximal parameter space for sterile neutrino dark matter with lepton asymmetries. The allowed range of sterile neutrinos' squared couplings extends by up to two orders of magnitude across a 5-60 keV mass range, and may be testable by X-ray, structure formation, and upcoming CMB observations. We will also discuss the origin of lepton flavor asymmetries: leptoflavorgenesis, and the recently reported helium-4 anomaly in the Universe associated with it.