A5030804814- Cosmology and Gravitation Theories
- Black Holes and Theoretical Physics
- Pulsars and Gravitational Waves Research
- Particle physics theoretical and experimental studies
- Geophysics and Gravity Measurements
- Dark Matter and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Quantum, superfluid, helium dynamics
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Cold Atom Physics and Bose-Einstein Condensates
- Physics of Superconductivity and Magnetism
- Computational Physics and Python Applications
- Solar and Space Plasma Dynamics
- Quantum Chromodynamics and Particle Interactions
- Atomic and Subatomic Physics Research
- Neutrino Physics Research
- Stochastic processes and financial applications
- Quantum many-body systems
- Relativity and Gravitational Theory
- Numerical Methods and Algorithms
- Quantum Electrodynamics and Casimir Effect
- Experimental and Theoretical Physics Studies
- Gas Dynamics and Kinetic Theory
- Diffusion and Search Dynamics
The University of Tokyo
2012-2024
Kobe University
2024
Consejo Superior de Investigaciones Científicas
2022-2023
Universidad Autónoma de Madrid
2022-2023
Instituto de Física Teórica
2023
Deutsches Elektronen-Synchrotron DESY
2019-2022
Institute for Basic Science
2017-2020
High Energy Accelerator Research Organization
2016-2019
Tokyo University of Science
2014
We consider gravitational wave production by bubble collisions during a cosmological first-order phase transition. In the literature, such spectra have been estimated simulating dynamics, under so-called thin-wall and envelope approximations in flat background metric. However, we show that, within these assumptions, spectrum can be an analytic way. Our estimation is based on observation that two-point correlator of energy-momentum tensor $⟨T(x)T(y)⟩$ expressed analytically assumptions....
During a cosmological first-order phase transition, particles of the plasma crossing bubble walls can radiate gauge boson. The resulting pressure cannot be computed perturbatively for large coupling constant and/or supercooling. We resum real and virtual emissions at all leading-log orders, both analytically numerically using Monte-Carlo simulation. find that radiated bosons are dominantly soft retarding on relativistic is linear in Lorentz boost order parameter, up to log. further...
We study particle production at the preheating era in inflation models with nonminimal coupling $\xi \phi^2R$ and quartic potential $\lambda \phi^4/4$ for several cases: real scalar inflaton, complex inflaton Abelian Higgs inflaton. point out that proceeds much more violently than previously thought. If is a scalar, phase degree of freedom produced first stage preheating. field, longitudinal gauge boson similarly violent. This caused by spike-like feature time dependence which may be...
We study gravitational-wave production from bubble dynamics (bubble collisions and sound waves) during a cosmic first-order phase transition with an analytic approach. first propose modeling the system thin-wall approximation but without envelope often adopted in literature, order to take propagation after into account. The walls our setup are considered as scalar field configuration and/or bulk motion of fluid. next write down expressions for spectrum, evaluate them numerical methods. It is...
We study the production of light particles due to oscillation Hubble parameter or scale factor. Any coherently oscillating scalar field, irrespective its energy fraction in Universe, imprints such an feature on them. Not only Einstein gravity but extended models, as models with nonminimal (derivative) coupling and $f(R)$ gravity, lead present a convenient way estimate gravitational particle rate these circumstances. Cosmological implications production, dark matter/radiation moduli problem,...
We study the cosmological history of classical conformal $B-L$ gauge extension standard model, in which physical scales are generated via Coleman-Weinberg-type symmetry breaking. Especially, we consider thermal phase transition U$(1)_{B-L}$ early universe and resulting gravitational-wave production. Due to invariance, tends be a first-order one with ultra-supercooling, enhances strength produced gravitational waves. show that, requiring (1) is broken after reheating, (2) coupling does not...
We point out that the inflaton inevitably couples to all non-conformally coupled matters gravitationally through an oscillation in Hubble parameter or cosmic scale factor. It leads particle production during regime, which is most efficient just after inflation. Moreover, analysis extended model with non-minimal couplings gravity, oscillates more violently. apply our results graviton by inflaton: gravitons are also produced inflation, but coupling does not induce decay into pair.
Abstract First-order cosmological phase transitions in the early Universe source sound waves and, subsequently, a background of stochastic gravitational waves. Currently, predictions these rely heavily on simulations Higgs field coupled to plasma Universe, former providing latent heat transition. Numerically, this is rather demanding task since several length scales enter dynamics. From smallest largest, are thickness interface separating different phases, shell waves, and average bubble...
Abstract We develop a tool for the analysis of stochastic gravitational wave backgrounds from cosmological first-order phase transitions with LISA: we initiate template databank these signals, prototype their searches, and forecast reconstruction. The templates encompass signals sourced by bubble collisions, sound waves turbulence. Accounting Galactic extra-Galactic foregrounds, region parameter space that LISA will reconstruct better than ∼ 10% accuracy, if certain experimental theoretical...
We discuss the unique phenomenology of first-order phase transitions catalyzed by primordial black holes (BHs). If number BHs within one Hubble volume is smaller than unity at time bubble nucleation, each around them can expand to size, and universe eventually filled with true vacuum much after nucleation. This super-slow transition predicts enhanced gravitational wave signals from collisions be tested in future observations. Moreover, remaining rare false patches give birth baby BHs, which...
Motivated by the recent IceCube result, we study high energy cosmic-ray neutrino flux from decay of a long-lived particle. Because neutrinos are so transparent, produced in past may also contribute to present flux. We point out that PeV events observed originate particle much heavier than if its lifetime is shorter cosmic time. It shown mass responsible for event can be as large $\sim 10^{10}\ {\rm GeV}$. discuss several possibilities acquire information about
It has been argued that the mixed Higgs-$R^2$ model acts as UV extension of Higgs inflation, pushing up its cut-off scale in vacuum close to Planck scale. In this letter, we study inflaton oscillation stage after focusing on effective mass phase direction field, which can cause a violent preheating process. We find "spikes" observed inflation still appear model. While spikes above Higgs-only case, they below when is extended with $R^2$ term though reheating cannot be completed particle...
We investigate the sensitivity of future space-based interferometers such as LISA and DECIGO to parameters new particle physics models which drive a first-order phase transition in early Universe. first perform Fisher matrix analysis on quantities characterizing gravitational-wave spectrum resulting from transition, peak frequency amplitude. next for determine properties latent heat time dependence bubble nucleation rate. Since these are determined by model physics, we can estimate expected...
We investigate the sensitivity of Higgs(-like) inflation to higher dimensional operators in nonminimal couplings and potential, both metric Palatini formalisms. find that, while inflationary predictions are relatively stable against around attractor point formalism, they extremely sensitive one: for latter, spoiled by $|\xi_4| \gtrsim 10^{-6}$ $(\xi_2 \phi^2 + \xi_4 \phi^4 \cdots)R$, or $|\lambda_6| 10^{-16}$ Jordan-frame potential $\lambda_4 \lambda_6 \phi^6 \cdots$ (both Planck units)....
The Laser Interferometer Space Antenna (LISA) has two scientific objectives of cosmological focus: to probe the expansion rate universe, and understand stochastic gravitational-wave backgrounds their implications for early universe particle physics, from MeV Planck scale. However, range potential applications gravitational wave observations extends well beyond these objectives. This publication presents a summary state art in LISA cosmology, theory methods, identifies new opportunities use...
We study scalar bubble collisions in first-order phase transitions focusing on the relativistic limit. propose `trapping equation' which describes wall behavior after collision, and test it with numerical simulations several setups. also examine energy dynamics collision discuss its implications to gravitational wave production.
Abstract We discuss the gravitational wave spectrum produced by first-order phase transitions seeded domain wall networks. This setup is important for many two-step as seen example in singlet extension of standard model. Whenever correlation length network larger than typical bubble size, this leads to a signal that shifted lower frequencies and with an enhanced amplitude compared homogeneous without walls. our results light recent PTA hints waves.
We study cosmological scenarios in which high-energy neutrinos are emitted from the decay of long-lived massive particles at cosmic time later than a redshift 10^6. The neutrino events recently observed by IceCube experiment suggest new source cosmic-ray neutrinos; heavy particle can be one possibilities. calculate spectrum particles, taking account scattering processes with background neutrinos. Then, we derive bounds on scenario using observation flux. also constraints spectral distortions...
We study gravitational-wave production from bubble collisions in a cosmic first-order phase transition, focusing on the possibility of model separation by nucleation rate dependence resulting spectrum. By using method relating spectrum with two-point correlator energy-momentum tensor < T(x)T(y) >, we first write down analytic expressions for Gaussian correction to commonly used rate, Γ ∝ eβ tarrow t−γ2t2, under thin-wall and envelope approximations. Then quantitatively investigate how...
In a wide class of new physics models, there exist scalar fields that obtain vacuum expectation values high energy scales. We study the possibility standard model Higgs field has experienced first order phase transition at scale due to couplings with these fields. estimate amount gravitational waves produced by transition, and discuss observational consequences.
We study the effect of density perturbations on process first-order phase transitions and gravitational wave production in early Universe. are mainly interested how distribution nucleated bubbles is affected by fluctuations local temperature. find that large-scale ($H_* < k_* \beta$) result a larger effective bubble size at time collision, enhancing produced amplitude waves. The necessary for this enhancement ${\cal P}_\zeta (k_*) \gtrsim (\beta / H_*)^{-2}$, therefore signal from with...
We consider first order cosmological phase transitions (PTs) happening at late times below standard model temperatures <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mi>T</a:mi><a:mrow><a:mi>PT</a:mi></a:mrow></a:msub><a:mo>≲</a:mo><a:mi>GeV</a:mi></a:math>. The inherently stochastic nature of bubble nucleation and the finite number bubbles associated with a late-time PT lead to superhorizon fluctuations in completion time. compute how such eventually source...
A new setup of cosmic inflation with a periodic inflaton potential and conformal factor is discussed in the metric Palatini formulations gravity. As concrete example, we focus on natural-inflation-like potential, show that inflationary predictions fall into allowed region microwave background observations both formulations.