Zobrazeno 1 - 10
of 199
pro vyhledávání: '"HIRAMATSU, TAKASHI"'
Autor:
Aoki, Katsuki, Gorji, Mohammad Ali, Hiramatsu, Takashi, Mukohyama, Shinji, Pookkillath, Masroor C., Takahashi, Kazufumi
We study the cosmic microwave background (CMB) radiation in the unified description of the effective field theory (EFT) of dark energy that accommodates both scalar-tensor and vector-tensor theories. The boundaries of different classes of theories ar
Externí odkaz:
http://arxiv.org/abs/2405.04265
Publikováno v:
Journal of Cosmology and Astroparticle Physics, 06, 030 (2024)
We study the collisions of elastic superconducting strings, also referred to as current-carrying strings, formed in a $U_{\rm local}(1) \times U_{\rm global}(1)$ field-theory model, using three-dimensional numerical field-theoretic simulations. The b
Externí odkaz:
http://arxiv.org/abs/2312.16091
The evidence for a non-vanishing isotropic cosmic birefringence in recent analyses of the CMB data provides a tantalizing hint for new physics. Domain wall (DW) networks have recently been shown to generate an isotropic birefringence signal in the ba
Externí odkaz:
http://arxiv.org/abs/2312.14104
Autor:
Kobayashi, Tsutomu, Hiramatsu, Takashi
Higher-order scalar-tensor theories having an instantaneous mode do not develop the Ostrogradsky instability even if a seemingly dangerous mode is present. Such theories satisfy only partially the degeneracy conditions that are usually imposed to rem
Externí odkaz:
http://arxiv.org/abs/2310.11041
We study a simple axionlike model with a charged scalar $\phi$ and a double-charged scalar $\zeta$ of global $U(1)$ symmetry. A particular feature of our model is that a vacuum manifold is a torus knot. We consider a hierarchical symmetry-breaking sc
Externí odkaz:
http://arxiv.org/abs/2309.04248
Autor:
Arai, Shun, Aoki, Katsuki, Chinone, Yuji, Kimura, Rampei, Kobayashi, Tsutomu, Miyatake, Hironao, Yamauchi, Daisuke, Yokoyama, Shuichiro, Akitsu, Kazuyuki, Hiramatsu, Takashi, Hirano, Shin'ichi, Kase, Ryotaro, Katsuragawa, Taishi, Kobayashi, Yosuke, Namikawa, Toshiya, Nishimichi, Takahiro, Okumura, Teppei, Shiraishi, Maresuke, Shirasaki, Masato, Sunayama, Tomomi, Takahashi, Kazufumi, Taruya, Atsushi, Tokuda, Junsei
Since the discovery of the accelerated expansion of the present Universe, significant theoretical developments have been made in the area of modified gravity. In the meantime, cosmological observations have been providing more high-quality data, allo
Externí odkaz:
http://arxiv.org/abs/2212.09094
Autor:
Hiramatsu, Takashi
We put constraints on the degenerate higher-order scalar-tensor (DHOST) theories using the Planck 2018 likelihoods. In our previous paper, we developed a Boltzmann solver incorporating the effective field theory parameterised by the six time-dependen
Externí odkaz:
http://arxiv.org/abs/2205.11559
Autor:
Hiramatsu, Takashi, Kobayashi, Tsutomu
We provide a cosmological test of modified gravity with two tensorial degrees of freedom and no extra propagating scalar mode. The theory of gravity we consider admits a cosmological model that is indistinguishable from the $\Lambda$CDM model at the
Externí odkaz:
http://arxiv.org/abs/2205.04688
We discuss how the topological defects in the dark sector affect the Standard Model sector when the dark photon has a kinetic mixing with the QED photon. In particular, we consider the dark photon appearing in the successive gauge symmetry breaking,
Externí odkaz:
http://arxiv.org/abs/2109.12771
We systematically investigate the preheating behavior of single field inflation with an oscillon-supporting potential. We compute the properties of the emitted gravitational waves (GWs) and the number density and characteristics of the produced oscil
Externí odkaz:
http://arxiv.org/abs/2011.12201