104 citations · 676 across the 37 of their papers we have counts for
11 papers · 1 filter
Misalignment production of vector boson dark matter from axion-SU(2) inflation
Tomohiro Fujita, Kai Murai, Kazunori Nakayama +1
We present a new mechanism to generate a coherently oscillating dark vector field from axion-SU(2) gauge field dynamics during inflation. The SU(2) gauge field acquires a nonzero b…
Primordial Origin of Supermassive Black Holes from Axion Bubbles
Kentaro Kasai, Masahiro Kawasaki, Naoya Kitajima +3
We study a modification of the primordial black hole (PBH) formation model from axion bubbles. We assume that the Peccei-Quinn scalar rolls down in the radial direction from a larg…
Enhancement of gravitational waves at Q-ball decay including non-linear density perturbations
Masahiro Kawasaki, Kai Murai
The existence of a stochastic gravitational wave background is indicated by the recent pulsar timing array (PTA) experiments. We study the enhanced production of second-order gravi…
Can baryon asymmetry be explained by a large initial value before inflation?
Kai Murai, Fuminobu Takahashi, Masaki Yamada +1
We show that the baryon asymmetry of the Universe cannot be explained by a large initial value before inflation because it inevitably predicts correlated baryon isocurvature pertur…
A Novel Probe of Supersymmetry in Light of Nanohertz Gravitational Waves
Kai Murai, Wen Yin
A new era of exploring the early Universe may have begun with the recent strong evidence for the stochastic gravitational wave (GW) background from the data reported by NANOGrav, E…
Gravitational Waves from Domain Wall Collapse, and Application to Nanohertz Signals with QCD-coupled Axions
Naoya Kitajima, Junseok Lee, Kai Murai +2
We study for the first time the gravitational waves generated during the collapse of domain walls, incorporating the potential bias in the lattice simulations. The final stages of…
The QCD Axion: A Unique Player in the Axiverse with Mixings
Kai Murai, Fuminobu Takahashi, Wen Yin
In an axiverse with numerous axions, the cosmological moduli problem poses a significant challenge because the abundance of axions can easily exceed that of dark matter. The well-e…
Clustering of Primordial Black Holes from QCD Axion Bubbles
Kentaro Kasai, Masahiro Kawasaki, Naoya Kitajima +3
We study the clustering of primordial black holes (PBHs) and axion miniclusters produced in the model proposed to explain the LIGO/Virgo events or the seeds of the supermassive bla…
Constraint on Early Dark Energy from Isotropic Cosmic Birefringence
Johannes R. Eskilt, Laura Herold, Eiichiro Komatsu +3
Polarization of the cosmic microwave background (CMB) is sensitive to new physics violating parity symmetry, such as the presence of a pseudoscalar "axionlike" field. Such a field…
EMPRESS. XII. Statistics on the Dynamics and Gas Mass Fraction of Extremely-Metal Poor Galaxies
Yi Xu, Masami Ouchi, Yuki Isobe +49
We present demography of the dynamics and gas-mass fraction of 33 extremely metal-poor galaxies (EMPGs) with metallicities of and low stellar masses of $10^4-…
Muon and non-thermal leptogenesis in model
Shintaro Eijima, Masahiro Ibe, Kai Murai
The gauged symmetry is the simplest possibility to explain the observed muon , while being consistent with the neutrino oscillations through the seesaw mechan…