165 citations · 2.5k across the 85 of their papers we have counts for
60 papers · 1 filter
Tunneling from a Slowly Rolling Multifield Background Using Tadpole Subtraction
Masaki Yamada
We study semiclassical tunneling in scalar field theories with slowly evolving homogeneous backgrounds. We formulate the problem by combining tadpole subtraction with an adiabatic…
Formation and scaling of strings for global symmetry
Masaki Yamada
We numerically investigate networks of global strings with multi-string junctions in a scalar field model whose vacuum manifold is $\mathrm{PSU}(N)=\mathrm{SU}(N)/\m…
Dark baryon from pure Yang-Mills theory and its GW signature from cosmic strings
Masaki Yamada, Kazuya Yonekura
We point out that SO() pure Yang-Mills theory provides a candidate for dark matter (DM) without the explicit need to impose any additional symmetry. The DM candidate is a parti…
Quantum decay of scalar and vector boson stars and oscillons into gravitons
Kazunori Nakayama, Fuminobu Takahashi, Masaki Yamada
We point out that a soliton such as an oscillon or boson star inevitably decays into gravitons through gravitational interactions. These decay processes exist even if there are no…
Axion dark matter from first-order phase transition, and very high energy photons from GRB 221009A
Shota Nakagawa, Fuminobu Takahashi, Masaki Yamada +1
We study an axion-like particle (ALP) that experiences the first-order phase transition with respect to its mass or potential minimum. This can be realized if the ALP obtains a pot…
Wash-in leptogenesis after axion inflation
Valerie Domcke, Kohei Kamada, Kyohei Mukaida +2
CP violation and the violation of baryon-minus-lepton number B-L do not necessarily have to occur simultaneously in order to accomplish successful leptogenesis. Instead, it suffice…
Formation of hot spots around small primordial black holes
Minxi He, Kazunori Kohri, Kyohei Mukaida +1
In this paper, we investigate the thermalization of Hawking radiation from primordial black holes (PBHs) in the early Universe, taking into account the interference effect on therm…
Cascades of high-energy SM particles in the primordial thermal plasma
Kyohei Mukaida, Masaki Yamada
High-energy standard model (SM) particles in the early Universe are generated by the decay of heavy long-lived particles. The subsequent thermalization occurs through the splitting…
A new constraint on primordial lepton flavour asymmetries
Valerie Domcke, Kohei Kamada, Kyohei Mukaida +2
A chiral chemical potential present in the early universe can source helical hypermagnetic fields through the chiral plasma instability. If these hypermagnetic fields survive until…
Gravitational production of dark photon dark matter with mass generated by the Higgs mechanism
Takanori Sato, Fuminobu Takahashi, Masaki Yamada
We study the gravitational production of dark photon dark matter during inflation, when dark photons acquire mass by the Higgs mechanism. In the previous study, it was assumed that…
Early-Universe Model Building
Pouya Asadi, Saurabh Bansal, Asher Berlin +37
Theoretical investigations into the evolution of the early universe are an essential part of particle physics that allow us to identify viable extensions to the Standard Model as w…
Baryon Asymmetric Universe from Spontaneous CP Violation
Kohei Fujikura, Yuichiro Nakai, Ryosuke Sato +1
Spontaneous CP violation, such as the Nelson-Barr (NB) mechanism, is an attractive scenario for addressing the strong CP problem while realizing the observed phase of the Cabibbo-K…
Leptoflavorgenesis: baryon asymmetry of the Universe from lepton flavor violation
Kyohei Mukaida, Kai Schmitz, Masaki Yamada
Charged-lepton flavor violation (CLFV) is a smoking-gun signature of physics beyond the Standard Model. The discovery of CLFV in upcoming experiments would indicate that CLFV proce…
Semiclassical analysis of axion-assisted and axion-driven pair production
Hiroyuki Kitamoto, Masaki Yamada
We study the pair production of fermions in a time dependent axion background with and without an electric background. We construct the adiabatic mode functions which incorporate t…
Cosmic Birefringence Triggered by Dark Matter Domination
Shota Nakagawa, Fuminobu Takahashi, Masaki Yamada
Cosmic birefringence is predicted if an axion-like particle (ALP) moves after the recombination. We show that this naturally happens if the ALP is coupled to the dark matter densit…
A natural and simple UV completion of the QCD axion model
Masaki Yamada, Tsutomu T. Yanagida
The novel PQ mechanism replaces the strong CP problem with some challenges in a model building. In particular, the challenges arise regarding i) the origin of an anomalous global s…
Trapping Effect for QCD Axion Dark Matter
Shota Nakagawa, Fuminobu Takahashi, Masaki Yamada
In the early universe, the potential of a scalar field can be significantly modified, and the scalar field may be trapped for a long time in a different location than the current v…
Wash-In Leptogenesis
Valerie Domcke, Kohei Kamada, Kyohei Mukaida +2
We present a leptogenesis mechanism based on the standard type-I seesaw model that successfully operates at right-handed-neutrino masses as low as a few 100 TeV. This mechanism, wh…
What if ALP dark matter for the XENON1T excess is the inflaton
Fuminobu Takahashi, Masaki Yamada, Wen Yin
The recent XENON1T excess in the electron recoil data can be explained by anomaly-free axion-like particle (ALP) dark matter with mass keV and the decay constan…
XENON1T excess from anomaly-free ALP dark matter and its implications for stellar cooling anomaly
Fuminobu Takahashi, Masaki Yamada, Wen Yin
Recently, an anomalous excess was found in the electronic recoil data collected at the XENON1T experiment. The excess may be explained by an axion-like particle (ALP) with mass of…
Spontaneous Baryogenesis from Axions with Generic Couplings
Valerie Domcke, Yohei Ema, Kyohei Mukaida +1
Axion-like particles can source the baryon asymmetry of our Universe through spontaneous baryogenesis. Here we clarify that this is a generic outcome for essentially any coupling o…
Strongly-interacting massive particle and dark photon in the era of intensity frontier
Ayuki Kamada, Masaki Yamada, Tsutomu T. Yanagida
A strongly interacting massive particle (SIMP) is an interesting candidate for dark matter (DM) because its self-interaction cross section can be naturally strong enough to address…
A more attractive scheme for radion stabilization and supercooled phase transition
Kohei Fujikura, Yuichiro Nakai, Masaki Yamada
We propose a new radion stabilization mechanism in the Randall-Sundrum spacetime, introducing a bulk gauge field which confines at a TeV scale. It turns out that the ra…
Unification for the Darkly Charged Dark Matter
Ayuki Kamada, Masaki Yamada, Tsutomu T. Yanagida
We provide a simple UV theory for a Dirac dark matter with a massless Abelian gauge boson. We introduce a single fermion transforming as the representation in the SO(10)$…