Hajime Otsuka

Note on arithmetic structure of modulus vacua in flux compactifications

Yukiya Furuta, Tatsuo Kobayashi, Tomoyasu Kori +3

We study modulus stabilization by background fluxes. Within the truncated complex-structure sector, the F-term conditions of the complex structure moduli are described by a holomor…

hep-ph2026

Textures of dimension-six operators in the SMEFT with non-invertible selection rules

Tatsuo Kobayashi, Hajime Otsuka, Morimitsu Tanimoto +1

We investigate the flavor structures of dimension-six operators in the Standard Model Effective Field Theory (SMEFT) subject to non-invertible selection rules. In particular, we cl…

Massive modes on magnetized blow-up manifold of $T^{2} / Z_{N}$

Tatsuo Kobayashi, Hajime Otsuka, Hikaru Uchida

We study massive modes on a magnetized blow-up manifold of $T^{2} / Z_{N}$ . The blow-up manifold can be constructed by appropriately replacing orbifold singular points with a pa…

Residual group-like symmetries in selection rules without group actions

Jun Dong, Tatsuo Kobayashi, Shuhei Miyamoto +2

We analyze loop-induced group-like symmetries in theories where fields are labeled by basis elements of a fusion algebra constructed from the conjugacy classes of finite groups. Al…

Yukawa Textures with Enhanced Symmetries in Heterotic Calabi-Yau Compactifications

Jun Dong, Tatsuo Kobayashi, Shuhei Miyamoto +1

We clarify the structure of Yukawa couplings and mass matrices for matter fields in heterotic string theory on smooth Calabi-Yau threefolds with standard embedding. The topological…

Modular weights of wave functions on magnetized torus

Tim Jeric, Tatsuo Kobayashi, Hajime Otsuka +2

We study the origin of modular weights of wave functions in magnetized $T^{2}$ models. It is explicitly demonstrated that the modular weights of the wave functions on magnetized $T…

Generalized CP from non-invertible selection rules

Tatsuo Kobayashi, Hajime Otsuka

We study a framework in which fields are labeled by basis elements of a fusion algebra with non-invertible fusion rules. In particular, we consider the case where fields are labele…

GUT-motivated non-invertible symmetry as a solution to the strong CP problem and the neutrino CP-violating phase

Tatsuo Kobayashi, Hajime Otsuka, Morimitsu Tanimoto +1

The unsuppressed CP violation in QCD is a problem in the standard model. If we have some mechanism to guarantee real determinants of the quark mass matrices, the vanishing physical…

Non-Invertible Selection Rules on Heterotic Non-Abelian Orbifolds

Tatsuo Kobayashi, Ryusei Nishida, Hajime Otsuka

We investigate coupling selection rules in heterotic string theory on non-Abelian orbifolds. Since boundary conditions on the orbifolds are classified by conjugacy classes of space…

Stringy Constraints on Modular Flavor Models

Keiya Ishiguro, Takafumi Kai, Tatsuo Kobayashi +1

We investigate stringy constraints on moduli spaces in modular flavor models by analyzing moduli-dependent threshold corrections in heterotic string vacua. While moduli play a cruc…

Non-invertible Symmetry as a Solution to the Strong CP Problem in a GUT-inspired Standard Model

Tatsuo Kobayashi, Hajime Otsuka, Tsutomu T. Yanagida

We propose a three-zero texture for the down-quark mass matrix within a $S U (5)$ GUT-inspired Standard Model, enforced by a non-invertible selection rule originating from $\mathbb{Z…

On discrete gauging and non-invertible selection rules

Jun Dong, Tim Jeric, Tatsuo Kobayashi +2

We clarify selection rules of conjugacy classes of several finite discrete groups where we deal with both gauged and ungauged cases. We find that the selection rules enjoy finite A…

Matter symmetries in supersymmetric standard models from non-invertible selection rules

Tatsuo Kobayashi, Hironobu Mita, Hajime Otsuka +1

We discuss phenomenological implications of non-invertible selection rules in the framework of the supersymmetric standard model. We find that a remnant $Z_{2}$ symmetry of…

Radiative neutrino mass models from non-invertible selection rules

Tatsuo Kobayashi, Hiroshi Okada, Hajime Otsuka

We apply non-invertible selection rules coming from a fusion algebra to radiative neutrino mass models where fields are labeled by the elements in the algebra. Since non-invertible…

hep-ph2025★ 17 cited

Lepton mass textures from non-invertible multiplication rules

Tatsuo Kobayashi, Hajime Otsuka, Morimitsu Tanimoto +1

We study the lepton mass textures, which are derived by $Z_{2}$ gauging of $Z_{M}$ symmetries. We can obtain various textures for the Yukawa couplings in the charged…

Classification of Modular Symmetries in Non-Supersymmetric Heterotic String theories

Shuta Funakoshi, Yuichi Koga, Hajime Otsuka

We study modular symmetries in non-supersymmetric heterotic string theories on toroidal backgrounds with Wilson line modulus, constructed by stringy Scherk-Schwartz compactificatio…

hep-ph2025★ 23 cited

More about quark Yukawa textures from selection rules without group actions

Tatsuo Kobayashi, Yume Nishioka, Hajime Otsuka +1

We study the coupling selection rules associated with non-group symmetries, i.e., $Z_{2}$ gauging of $Z_{M}$ symmetries. We clarify which Yukawa textures can be deriv…

hep-th2025★ 1 cited

Classification of Modular Symmetries in Type IIB Flux Landscape

Keiya Ishiguro, Takafumi Kai, Tatsuo Kobayashi +2

In this work, we study modular symmetries in type IIB flux landscape by investigating symplectic basis transformations of period vectors on toroidal orbifolds. To fix explicit cycl…

Quantum aspects of non-invertible flavor symmetries in intersecting/magnetized D-brane models

Shuta Funakoshi, Tatsuo Kobayashi, Hajime Otsuka

We discuss selection rules of chiral matters in type IIA intersecting and IIB magnetized D-brane models on toroidal orbifolds. Since the chiral matters on toroidal orbifolds are la…

Modular symmetry of localized modes

Tatsuo Kobayashi, Hajime Otsuka, Shohei Takada +1

We study the modular symmetry of localized modes on fixed points of $T^{2} / Z_{2}$ orbifold. First, we find that the localized modes with even (odd) modular weight generally ha…

Moduli stabilization and light axion by Siegel modular forms

Shuta Funakoshi, Junichiro Kawamura, Tatsuo Kobayashi +2

We discuss the stabilization of multiple moduli by utilizing Siegel modular forms in the framework of $S p (2 g, Z)$ modular invariant theories. We derive the stationary condi…

hep-ph2024

Yukawa textures from non-invertible symmetries

Tatsuo Kobayashi, Hajime Otsuka, Morimitsu Tanimoto

Phenomenological aspects of non-invertible symmetries, in particular the flavor structure of quarks and leptons, are studied. We start with a $Z_{M}$ discrete symmetry and g…