July 9, 2020 to January 31, 2025
Europe/Zurich timezone

Dear colleagues,

We would like to invite you to take part in the upcoming 161st Copernicus Webinar.

Time:               27th Feb., Tuesday, at 3pm CET (10 pm Beijing, 11 pm JST, 9am ET). 

Speaker:         Kohei Kamada (University of Chinese Academy of Science)

Title: Baryogenesis and baryon isocurvature perturbation from primordial magnetic fields 

Abstract: Gamma-ray observations of blazars suggest the existence of the intergalactic magnetic fields and their origin is interest for both astro physicsts and cosmologists. Among several proposals, magnetogenesis in the early Universe is an interesting option since it might also be a probe for the physics beyond the Standard Model of particle physics. Recently, it has also been proven that the baryon asymmetry of the Universe can be also generated if the magnetic fields are produced before the electroweak symmetry breaking with helicity without imposing any new physics. However, baryon isocurvature perturbations are also generated at the scale of the magnetic field coherence length in the mean time, which is constrained by the inhomogeneous Big Bang Nucleosynthesis. Note that this is an inevitable consequence of the Standard Model of particle physics. In this talk, I give generic constraints of the hypermagnetic field properties generated before the electroweak symmetry breaking. Noting that the baryon isocurvature perturbations are generated even from non-helical magnetic fields, I show that with reasonable parameter sets for the Standard Model of particle physics and magnetic field evolution laws, the intergalactic magnetic fields suggested by the blazar observations are hardly explained solely by the hypermagnetic fields generated before the electroweak symmetry breaking. Helical hypermagnetic fields can still be the origin of the present baryon asymmetry of the Unvierse, but we need an additional magnetogenesis or an unknown magnetic field amplification mechanism.

Zoom link:
Meeting ID: 421 480 1692
Passcode: cosmology


This series is co-organised by the cosmology groups in the following institutions (in alphabetical order): 

Harvard University, Hong Kong University of Science and Technology, Institut d'Astrophysique de Paris, Institute of Physics of the Czech Academy of Science, Jagiellonian University, Kyoto University, Leiden University, Ludwig Maximilians University, McGill University, Perimeter Institute, Polish Society on Relativity, The Pennsylvania State University, The University of Tokyo, Tsinghua University, University of Geneva, University of Groningen, University of Science and Technology of China, University of Waterloo.

Science Organising Committee members (in alphabetical order):

Niayesh Afshordi, Robert Brandenberger, Yifu Cai, Xingang Chen, Ema Dimastrogiovanni, Ruth Durrer, Ghazal Geshnizjani, Chunshan Lin, Jerome Martin, Jakub Mielczarek, Viatcheslav Mukhanov, Shinji Mukohyama, Subodh Patil, Misao Sasaki, Sarah Shandera, Wei Song, Alexander Vikman, Yi Wang, Zhong-Zhi Xianyu