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…

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…

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…

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…

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-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…

Flavor symmetries from modular subgroups in magnetized compactifications

Tatsuo Kobayashi, Kaito Nasu, Ryusei Nishida +2

We study the flavor structures of zero-modes, which are originated from the modular symmetry on $T_{1}^{2} \times T_{2}^{2}$ and its orbifold with magnetic fluxes. We introduce the constrai…

hep-th2024★ 27 cited

Non-invertible flavor symmetries in magnetized extra dimensions

Tatsuo Kobayashi, Hajime Otsuka

We discuss non-invertible symmetries in toroidal compactifications of higher dimensional Yang-Mills theory with magnetic fluxes, which can be regarded as an effective action of typ…

hep-th2024★ 2 cited

Stabilization of a twisted modulus on a mirror of rigid Calabi-Yau manifold

Keiya Ishiguro, Takafumi Kai, Hajime Otsuka

We study the stabilization of a twisted modulus in Type IIB flux compactifications on a mirror of the rigid Calabi-Yau threefold. By analyzing the effective action of twisted and u…