Details of a Researcher - Higaki, Tetsutaro

Fermion Hierarchies in SU(5) Grand Unification from Γ6' Modular Flavor Symmetry

Yoshihiko Abe, Tetsutaro Higaki, Junichiro Kawamura, Tatsuo Kobayashi

Journal of High Energy Physics （Springer Science+Business Media) 08 （ 097 ） 1 - 25 2023.08

Research paper (scientific journal), Accepted

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We construct a model in which the hierarchies of the quark and lepton masses and mixing are explained by the Γ′6 modular flavor symmetry. The hierarchies are realized by the Froggatt-Nielsen-like mechanism due to the residual ZT6 symmetry, approximately unbroken at τ∼i∞. We argue that the Γ(′)6 symmetry is the minimal possibility to realize the up-type quark mass hierarchies, since the Yukawa matrix is symmetric. We find a combination of the representations and modular weights and then show numerical values of O(1) coefficients for the realistic fermion hierarchies.
- Access to Document (DOI)
Quark and lepton hierarchies from S4' modular flavor symmetry

Yoshihiko Abe, Tetsutaro Higaki, Junichiro Kawamura, Tatsuo Kobayashi

Physics Letters B （Elsevier) 842 （ 137977 ） 1 - 9 2023.07

Research paper (scientific journal), Accepted

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We propose models in which the hierarchical structures of the masses and
mixing in both quark and lepton sectors are explained by the $S_4^\prime$
modular flavor symmetry near the fixed point $\tau \sim i\infty$. The model
provides the first explicit example which explains hierarchies of both quarks
and leptons. The hierarchies are realized by powers of $\epsilon = e^{2\pi i
\tau/4} = \mathcal{O}(0.01)$ and $2\,\mathrm{Im}\,\tau \sim 5$, where $\tau$
being the modulus. The small parameter $\epsilon$ plays a role of flavon in the
Froggatt-Nielsen mechanism under the residual $Z_4^T$ symmetry, and powers of
$2\,\mathrm{Im}\,\tau$ in the Yukawa couplings are controlled by modular
weights via the canonical normalization. The doublet quarks are identified to a
$S_4^\prime$ triplet to explain the hierarchical structure of the quark mixing
angles, while the doublet leptons are composed of three singlets for the large
mixing angles in the lepton sector. We show that the $S_4^\prime$ modular
symmetry alone can explain the hierarchies in both quark and lepton sectors by
$\mathcal{O}(1)$ coefficients.
- Access to Document (DOI)
Moduli inflation from modular flavor symmetries

Yoshihiko Abe, Tetsutaro Higaki, Fumiya Kaneko, Tatsuo Kobayashi, Hajime Otsuka

Journal of High Energy Physics （Springer Science+Business Media) 6 （ 187 ） 1 - 39 2023.06

Research paper (scientific journal), Joint Work, Accepted

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We study slow-roll inflation model controlled by the modular flavor symmetry.
In the model, the modulus field plays a role of inflaton and the introduction
of the stabilizer field coupled to a modular form in the superpotential
produces the inflaton potential. In order to generate the flat direction for
the slow-roll inflation, we consider the K\"{a}hler potential corrected by the
modular form. It is noted that the modulus field perpendicular to the inflaton
direction is stabilized during the inflation. The model is turns out to be
consistent with the current observations and behaves similarly to the
$\alpha$-attractor models in some parameter spaces. The inflaton rolls down to
the CP-symmetric vacuum at the end of inflation.
- Access to Document (DOI)
Quark masses and CKM hierarchies from S4′ modular flavor symmetry

Yoshihiko Abe, Tetsutaro Higaki, Junichiro Kawamurab, Tatsuo Kobayashi

e-Print: 2301.07439 [hep-ph] 2023.01

Research paper (other academic), Joint Work
Formation of Chiral Soliton Lattice

Tetsutaro Higaki, Kohei Kamada, Kentaro Nishimura

Physical Review D （American Physical Society) 106 （ 096022 ） 2022.11

Research paper (scientific journal), Accepted

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The Chiral Soliton Lattice (CSL) is a lattice structure composed of domain
walls aligned in parallel at equal intervals, which is energetically stable in
the presence of a background magnetic field and a finite (baryon) chemical
potential due to the topological term originated from the chiral anomaly. We
study its formation from the vacuum state, with describing the CSL as a layer
of domain-wall disks surrounded by the vortex or string loop, based on the
Nambu-Goto-type effective theory. We show that the domain wall nucleates via
quantum tunneling when the magnetic field is strong enough. We evaluate its
nucleation rate and determine the critical magnetic field strength with which
the nucleation rate is no longer exponentially suppressed. We apply this
analysis to the neutral pion in the two-flavor QCD as well as the axion-like
particles (ALPs) with a finite (baryon) chemical potential under an external
magnetic field. In the former case, even though the CSL state is more
energetically stable than the vacuum state and the nucleation rate becomes
larger for sufficiently strong magnetic field, it cannot be large enough so
that the nucleation of the domain walls is not exponentially suppressed and
promoted, without suffering from the tachyonic instability of the charged pion
fluctuations. In the latter case, we confirm that the effective interaction of
the ALPs generically includes the topological term required for the CSL state
to be energetically favored. We show that the ALP CSL formation is promoted if
the magnetic field strength and the chemical potential of the system is
slightly larger than the scale of the axion decay constant.

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Presentations 【 Display / hide 】

Approaches to effective field theories of string theory

檜垣徹太郎

Particle physics and cosmology from string compactification,

2023.09
,
Oral presentation (invited, special)
Modular flavor symmetry and cosmology

Tetsutaro Higaki

Kobe Workshop on Cosmology and Fundamental Physics 2023,

2023.03
,
Oral presentation (invited, special)
New 4D EFT from 10D non-Abelian DBI action in magnetic compactifications

Tetsutaro Higaki

KEK Theory Workshop 2021,

2021.12
,
Oral presentation (general)
4D effective action from 10D non-Abelian DBI action with magnetic flux background

Tetsutaro Higaki

Strings and Fields 2021,

2021.08
,
Oral presentation (general)
Implications of the weak gravity conjecture in anomalous quiver gauge theories

Tetsutaro Higaki

KEK Theory workshop 2020 (online) ,

2020.12
,
Oral presentation (general), KEK theory group

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

沼地予想とモジュライから探る究極理論の観測的性質（基盤研究(C)）

2022.04

-

2027.03

基盤研究(C), Principal investigator
隠れたセクターの場や粒子が引き起こす多様な宇宙現象を用いた究極理論探査（基盤研究A・分担）

2015.04

-

2018.03

Coinvestigator(s)
超弦理論におけるモジュライ場の現象論的、宇宙論的側面の研究（若手研究B）

2013.04

-

2015.03

Principal investigator
超弦理論におけるモジュライ場の現象論的、宇宙論的側面の研究（日本学術振興会優秀若手研究者海外派遣事業 (特別研究員)）

2009

-

2010

Principal investigator
超弦理論におけるモジュライ場の現象論的、宇宙論的側面の研究（学振PD）

2007.04

-

2010.03

Principal investigator