Article
Astronomy & Astrophysics
Yi-Peng Wu, Kalliopi Petraki
Summary: By using a multi-field stochastic approach, this study examines the vacuum expectation value during inflation and suggests a mechanism for baryogenesis, concluding that the charged scalar mass at the order of H-* is favored by the isocurvature constraints at a Hubble scale of 10^13 GeV.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Thomas C. Gehrman, Barmak Shams Es Haghi, Kuver Sinha, Tao Xu
Summary: Gravitational waves in the MHz-GHz frequency range are motivated by various phenomena in the early Universe, including oscillons, preheating, and cosmic strings. This study points out that baryogenesis can also serve as a motivation to study gravitational waves within this frequency range. The connection is through primordial black holes (PBHs), which induce baryogenesis through Hawking radiation and also induce gravitational waves through the effects of scalar fluctuations. The results emphasize the importance of probing the ultra high frequency gravitational wave frontier.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Kohei Kamada, Fumio Uchida, Jun'ichi Yokoyama
Summary: The decay of hypermagnetic helicity at electroweak symmetry breaking may have produced baryon asymmetry, however, fully helical magnetic field may not be strong enough to explain the origin of intergalactic magnetic field; the combination of helical and nonhelical primordial magnetic fields may explain both, but is ruled out by the constraint on amplitude of baryon isocurvature perturbations.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Kunio Kaneta, Kin-ya Oda
Summary: This paper studies the non-thermal phase space distribution of the Higgs field during reheating, focusing on both primordial condensate and stochastic fluctuations. The study finds that the decay of stochastic fluctuations is dominated by the soft-relativistic and hard spectra, and that the primordial condensate and stochastic fluctuations decay almost simultaneously.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Kunio Kaneta, Kin-ya Oda
Summary: This paper studies the properties of the Higgs field in the non-thermal phase space distribution after the end of inflation, focusing on the contributions of primordial condensate and stochastic fluctuations, and obtains analytic formulas. The perturbative Higgs decay during reheating is discussed as a possible consequence of the non-thermal Higgs spectrum and it is found that the primordial condensate and stochastic fluctuations decay almost at the same time.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Dhong Yeon Cheong, Sung Mook Lee, Seong Chan Park
Summary: Research shows that primordial black holes can be produced in a minimal UV extension of Higgs inflation with an included R-2 term. Parameters consistent with Standard Model measurements and Planck observation results indicate that M-PBH falls within the range of (10^(-16), 10^(-15))M⊙, with significant abundance, potentially making up the majority of dark matter.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Masahiro Kawasaki, Shusuke Ueda
Summary: This paper investigates the supersymmetric implementation of Affleck-Dine inflation, which successfully achieves inflation and baryogenesis, and shows that the isocurvature perturbation can be ignored, thus being consistent with observations.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Kimmo Kainulainen
Summary: In this study, CP-violating transport equations for fermions in electroweak baryogenesis are derived from the CTP formalism with thermal corrections at the one-loop level. It is found that the VIA method leads to ill-defined source terms due to an assumption, while the SC method accurately reproduces current divergence equations and captures semiclassical source terms effectively. The results also show that both VIA and collisional source terms reported in previous literature are ambiguous and vanish in a consistent calculation.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Dhong Yeon Cheong, Kazunori Kohri, Seong Chan Park
Summary: This paper introduces the effects of the running of the Higgs self coupling on early universe cosmology, particularly the phenomena of primordial black holes and stochastic gravitational waves. These phenomena can be further studied using proposed gravitational wave observatories.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Mainak Chakraborty, Sourov Roy
Summary: The expansion rate of the Universe deviates from the standard value when a new scalar field contributes to the total energy density. Analytical solutions of the Boltzmann equations become unsuitable in this non-standard scenario due to non-trivial modifications. In this study, we derive analytical expressions for the efficiency factor using certain approximations and compare them with numerical solutions. Faster expansion of the Universe reduces the washout of asymmetry, allowing a larger fraction of the asymmetry to survive. The alteration of cosmology does not affect the underlying particle physics model responsible for the CP asymmetry, resulting in a larger final baryon asymmetry in the non-standard scenario. This suggests a relaxation of the lower bound of the lightest right-handed neutrino mass required to produce adequate asymmetry, which is consistent with current experimental data.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Georgios Aliferis, Vasilios Zarikas
Summary: A successful baryogenesis mechanism is proposed in the cosmological framework of Brans-Dicke modified gravity, involving features such as primordial black hole production, Hawking radiation reheating, domain wall formation, and no need for a first-order phase transition.
Our proposed scenario provides black hole domination and efficient baryogenesis for smaller CP-violating angles compared to the same mechanism applied in a Friedmann-Robertson-Walker cosmological background.
Article
Astronomy & Astrophysics
Andreas Ringwald, Ken'ichi Saikawa, Carlos Tamarit
Summary: This paper analyzes the spectrum of primordial gravitational waves predicted in the SMASH model, which addresses multiple fundamental problems in particle physics and cosmology. The unique prediction for the critical temperature of the PQ phase transition in the model leads to a drastic change in the universe's equation of state. Future high sensitivity GW experiments, like DECIGO, are expected to detect the nontrivial features resulting from the PQ phase transition in this model.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Antonio Ambrosone, Roberta Calabrese, Damiano F. G. Fiorillo, Gennaro Miele, Stefano Morisi
Summary: A new baryogenesis mechanism was proposed by Dolgov and Pozdnyakov, where baryon asymmetry is produced without violating baryon number at the Lagrangian level. However, further analysis revealed fundamental issues in the scenario, including the initial increase in baryon asymmetry by PBH absorption followed by complete absorption at later times. Additionally, the proposed CP-violation model in this framework was found to be qualitatively correct but quantitatively inconsistent with observed baryon asymmetry.
Article
Astronomy & Astrophysics
Gilles Buldgen, Marco Drewes, Jin U. Kang, Ui Ri Mun
Summary: We present a general method to obtain an effective Markovian quantum kinetic equation for a slowly evolving scalar field in an adiabatically evolving background. The method requires minimal assumptions about the field's interactions and the composition of the background, as long as certain conditions regarding the coupling constants, time scales, and field derivatives are satisfied. The resulting equation of motion is expressed in terms of an effective potential and friction coefficients.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Rajeev Kumar Jain, P. Jishnu Sai, Martin S. Sloth
Summary: This study calculates the primordial correlation between gravitons and a non-minimally coupled abelian gauge field in the early universe, and finds that this correlation satisfies new consistency relations in the three-point cross-correlation functions. The study shows that the interaction between gravitons and gauge fields may have implications for cosmological observables today.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Multidisciplinary
Keisuke Inomata, Masahiro Kawasaki, Kyohei Mukaida, Tsutomu T. Yanagida
Summary: The study suggests that the axionlike curvaton model can explain the primordial black holes in both the LIGO-Virgo events and NANOGrav results, with the non-Gaussianity suppressing the gravitational waves associated with PBHs.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Particles & Fields
Valerie Domcke, Yohei Ema, Kyohei Mukaida
Summary: This study highlights an enhancement in the pair production rate of charged fermions in a strong electric field with the presence of a time dependent classical axion-like background field, termed as the axion assisted Schwinger effect. The enhancement is attributed to coupling between fermion spin and momentum induced by the axion velocity. This result has implications for axion cosmology, particularly in axion inflation and axion dark matter detection.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Multidisciplinary
Valerie Domcke, Kohei Kamada, Kyohei Mukaida, Kai Schmitz, Masaki Yamada
Summary: This mechanism, wash-in leptogenesis, operates at low masses of right-handed neutrinos without requiring CP violation, even in the regime of strong wash-out. By generalizing standard freeze-out leptogenesis to a nonminimal cosmological background, it allows for the generation of a nonvanishing B - L asymmetry using chemical potentials generated at high temperatures.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Particles & Fields
Tobias Binder, Kyohei Mukaida, Bruno Scheihing-Hitschfeld, Xiaojun Yao
Summary: This article presents a complete next-to-leading order calculation of the non-Abelian electric field correlator in a SU(N-c) plasma, providing insights into the properties of the plasma that are relevant for heavy particle bound state formation and dissociation.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Yohei Ema, Kyohei Mukaida, Kazunori Nakayama
Summary: The hidden sector scalar field generically couples to quadratic curvature through dimension five operators, potentially inducing decays into graviton pairs. Decay of the scalar field can produce a significant amount of stochastic cosmic graviton background at high frequencies due to the suppression scale being determined by the mass of heavy particles rather than the Planck scale. The resulting graviton spectrum is computed in specific models, highlighting the phenomenological interest of these scalar couplings.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Multidisciplinary
Valerie Domcke, Camilo Garcia-Cely, Nicholas L. Rodd
Summary: The study indicates that rapid progress is expected in detecting gravitational waves, especially through increasing the volume of instruments and making simple modifications to the pickup loop. While the current strain sensitivity to gravitational waves is weak, breakthroughs are expected in the future.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Kyohei Mukaida, Kai Schmitz, Masaki Yamada
Summary: Charged-lepton flavor violation (CLFV) is a distinct feature of physics beyond the standard model, which plays an important role in the early universe. This Letter points out that efficient CLFV interactions create new pathways for generating the baryon asymmetry of the universe, and the conversion factor from lepton flavor asymmetry to baryon asymmetry is naturally explained by the suppression of charged-lepton Yukawa couplings squared.
PHYSICAL REVIEW LETTERS
(2022)
Article
Astronomy & Astrophysics
Tomohiro Fujita, Jun'ya Kume, Kyohei Mukaida, Yuichiro Tada
Summary: This study focuses on the axionic inflaton model with the Chern-Simons coupling and finds that the backreaction from charged particles suppresses the amplitude of gauge fields, leading to the dominance of charged particles in the evolution. The findings provide a basis for connecting inflationary models to phenomena such as baryogenesis and magnetogenesis.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Particles & Fields
Yu Hamada, Ryuichiro Kitano, Ryutaro Matsudo, Kyohei Mukaida
Summary: The Maxwell equations suggest that a varying theta term can produce E·B under the background of a non-zero magnetic field B. The underlying mechanism of the Witten effect, where a magnetic monopole becomes a dyon, has been understood by the presence of an effective axion-like degree of freedom. The chiral anomaly implies that a non-zero E·B induces chiral charge in the system, and the discussion explores whether this chiral charge is generated in the massless limit when considering the axion-like degree of freedom.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Kyohei Mukaida, Masaki Yamada
Summary: This paper investigates the thermalization of high-energy standard model particles in thermal plasma, considering the Landau-Pomeranchuk-Migdal effect. The distribution function of each particle species is calculated numerically and analytically. The results demonstrate that, after multiple splittings, the particle distributions converge to certain values at low momentum, independent of the high-energy particles injected by inflaton decay. This is helpful for calculating the dark matter abundance produced during the pre-thermal phase.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Valerie Domcke, Keisuke Harigaya, Kyohei Mukaida
Summary: We study the transfer of charge between complex scalar fields and find that under certain conditions, this transfer can be very efficient. This has important implications for cosmological studies involving complex scalar fields.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Astronomy & Astrophysics
Tomohiro Fujita, Kyohei Mukaida, Yuichiro Tada
Summary: In this study, we develop a stochastic formalism for U(1) gauge fields coupled with a rolling pseudo-scalar field during inflation. We derive the Langevin equations for the physical electromagnetic fields and study their analytic solutions. Through numerical simulation, we demonstrate that the averaged electromagnetic fields over the Hubble scale continuously change their direction and fluctuate around the analytically obtained expectation values. While the isotropy is spontaneously broken in each local Hubble patch, it is globally preserved by averaging all the Hubble patches.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Particles & Fields
Valerie Domcke, Yohei Ema, Kyohei Mukaida
Summary: This paper investigates the problem of particle production in a time-dependent background, focusing on the transient effects of fermions in a homogeneous axion background. The definition of particles and antiparticles at intermediate times in the presence of external fields is more ambiguous compared to the asymptotic states in conventional cases, and these external fields also lead to divergences that require regularization.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Multidisciplinary
Valerie Domcke, Kohei Kamada, Kyohei Mukaida, Kai Schmitz, Masaki Yamada
Summary: This letter investigates the relationship between helical hypermagnetic fields and fermion asymmetry in the early Universe caused by chiral chemical potential. The study demonstrates that even with zero total lepton number, a mechanism can be triggered through lepton flavor asymmetry. This sets a constraint on lepton flavor asymmetry at temperatures above 106 GeV, which is about two orders of magnitude stronger than current limits from cosmic microwave background and primordial nucleosynthesis.
PHYSICAL REVIEW LETTERS
(2023)