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SUMMARY:Primordial hypermagnetic fields constrained by baryon isocurvature
  perturbations
DTSTART:20210329T140000
DTEND:20210329T153000
DTSTAMP:20260506T220642Z
UID:46196241e83dd60b2e4ff4b67713e5516bd34c306251d3594e866770
CATEGORIES:Conferences - Seminars
DESCRIPTION:Kohei Kamada (Tokyo)\nGamma-ray observations of blazars sugges
 t the existence of the intergalactic magnetic fields and their origin is i
 nterest 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 particl
 e physics. \nRecently\, it has also been proven that the baryon asymmetry
  of the Universe can be also generated without imposing any new physics if
  the magnetic fields are produced before the electroweak symmetry breaking
  with helicity. \nHowever\, baryon isocurvature perturbations are also ge
 nerated at the scale of the magnetic field coherence length in the mean ti
 me\, which is constrained by the inhomogeneous Big Bang Nucleosynthesis. N
 ote that this is an inevitable consequence of the Standard Model of partic
 le physics. \nIn this talk\, I give generic constraints of the hypermagne
 tic field properties generated before the electroweak symmetry breaking. 
 \nNoting that the baryon isocurvature perturbations are generated even fro
 m non-helical magnetic fields\, I show that with reasonable parameter sets
  for the Standard Model of particle physics and magnetic field evolution l
 aws\, the intergalactic magnetic fields suggested by the blazar observatio
 ns are almost impossible to be explained solely by the hypermagnetic field
 s generated before the electroweak symmetry breaking. \nHelical hypermagn
 etic fields can still be the origin of the present baryon asymmetry of the
  Unvierse\, but we need an additional magnetogenesis or an unknown magneti
 c field amplification mechanism. 
LOCATION:https://epfl.zoom.us/j/86585160855?pwd=YzduazV3THprNmRLaFNoV0EweE
 1wQT09
STATUS:CONFIRMED
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