165 citations · 1.9k across the 61 of their papers we have counts for
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New comprehensive description of the scaling evolution of the cosmological magneto-hydrodynamic system
Fumio Uchida, Motoko Fujiwara, Kohei Kamada +1
We study the evolution of primordial magnetic fields until the recombination epoch, which is constrained by the conservation of magnetic helicity density if they are maximally heli…
New description of the scaling evolution of the cosmological magneto-hydrodynamic system
Fumio Uchida, Motoko Fujiwara, Kohei Kamada +1
We present a new description of cosmological evolution of the primordial magnetic field under the condition that it is non-helical and its energy density is larger than the kinetic…
Chiral effects in astrophysics and cosmology
Kohei Kamada, Naoki Yamamoto, Di-Lun Yang
The microscopic quantum nature of elementary particles, chirality, leads to macroscopic phenomena like the chiral anomaly, chiral magnetic effect, and chiral plasma instability. We…
Baryon isocurvature constraints on the primordial hypermagnetic fields
Kohei Kamada, Fumio Uchida, Jun'ichi Yokoyama
It has been pointed out that hypermagnetic helicity decay at the electroweak symmetry breaking may have produced the observed baryon asymmetry of the Universe through the chiral an…
Gravitational Waves from Primordial Magnetic Fields via Photon-Graviton Conversion
Tomohiro Fujita, Kohei Kamada, Yuichiro Nakai
We explore a novel process in the early Universe in which thermalized photons are converted into gravitons in the presence of strong primordial magnetic fields. It is found that th…
Baryogenesis from Decaying Magnetic Helicity
Kohei Kamada, Andrew J. Long
As a result of the Standard Model chiral anomalies, baryon number is violated in the early universe in the presence of a hypermagnetic field with varying helicity. We investigate w…