The Next-to-Minimal Supersymmetric Standard Model (NMSSM) provides a natural
framework to realize a low-scale supersymmetric (SUSY) model, where a singlet
superfield is added to the minimal model to generate a SUSY-scale higgsino mass
term with it...

We study the phenomenological implications of the modular symmetry of lepton flavors facing recent experimental data of neutrino
oscillations. The mass matrices of neutrinos and charged leptons are
essentially given by fixin...

We investigate origins of predictive one-zero neutrino mass textures in a
systematic way. Here we search Abelian continuous(discrete) global symmetries,
and non-Abelian discrete symmetries, and show how to realize these neutrino
masses. Then we pr...

We study the modular symmetry in magnetized D-brane models on .
Non-Abelian flavor symmetry in the model with magnetic flux (in a
certain unit) is a subgroup of the modular symmetry. We also study the modular
symmetry in heterotic...

Tatsuo Kobayashi, Naoya Omoto, Hajime Otsuka, Takuya H. Tatsuishi

Phys. Rev. D 97, 106006 (2018) Nov 2017

We propose a new type of Kähler moduli stabilization mechanisms in type IIB
superstring theory on Calabi-Yau manifolds with the positive Euler number. The
overall Kähler modulus can be perturbatively stabilized by radiative
corrections due to ...

We study an axion inflation model recently proposed within the framework of
type IIB superstring theory, where we pay a particular attention to a
sub-Planckian axion decay constant. Our axion potential can lead to the small
field inflation with a ...

We study the flavor structure in heterotic string theory on
six-dimensional torus with magnetic fluxes. In particular, we focus on models
with the flavor symmetries and . In both models, we can
realize the realistic ...

We study the next-to-minimal supersymmetric standard model (NMSSM) with the
TeV scale mirage mediation, which is known as a solution for the little
hierarchy problem in supersymmetry. Our previous study showed that 125 GeV
Higgs boson is realized ...

We classify the combinations of parameters which lead three generations of
quarks and leptons in the framework of magnetized twisted orbifolds on
, , and with allowing nonzero discretized
Wilson line phases an...

We revisit the discrete dark matter model with flavor symmetry
originally introduced by M.Hirsch {\it et.al}. We show that radiative
corrections can lead to non-zero and non-zero mass for the
lightest neutrino. We find an inter...

Tatsuo Kobayashi, Naoya Omoto, Hajime Otsuka, Takuya H. Tatsuishi

Phys. Rev. D 96, 046004 (2017) Apr 2017

We propose a new type of moduli stabilization scenario where the
supersymmetric and supersymmetry-breaking minima are degenerate at the leading
level. The inclusion of the loop-corrections originating from the matter fields
resolves this degenerac...

We study Kähler moduli stabilizations in semi-realistic magnetized D-brane
models based on toroidal orbifolds. In type IIB
compactifications, 3-form fluxes can stabilize the dilaton and complex
structure moduli fields, but ther...

We study general class of small-field axion inflations which are the mixture
of polynomial and sinusoidal functions suggested by the natural and axion
monodromy inflations. The axion decay constants leading to the successful axion
inflations are s...

Based on the result of classification in our previous work, we exhaustively
investigate Yukawa sector of model on magnetized orbifolds
, , and by evaluating
ratios of the mass eigenvalue...

We study the moduli-induced gravitino problem within the framework of the
phenomenologically attractive mirage mediations. The huge amount of gravitino
generated by the moduli decay can be successfully diluted by introducing an
extra light modulus...

We consider domain walls in the symmetric NMSSM. The spontaneous
discrete symmetry breaking produces domain walls, and the stable domain walls
are problematic. Thus, we assume the symmetry is slightly but explicitly
broken and th...

We study heterotic string theory on torus with magnetic fluxes.
Non-vanishing fluxes can lead to non-universal gauge kinetic functions for
which is the important features of
heterotic string the...

We discuss an effective way for analyzing the system on the magnetized
twisted orbifolds in operator formalism, especially in the complicated cases
, and . We can obtain the exact and
analytical results whic...

We study the structure of Yukawa matrices derived from the supersymmetric
Yang-Mills theory on magnetized orbifolds, which can realize the observed quark
and charged lepton mass ratios as well as the CKM mixing angles, even with a
small number of ...

Tatsuo Kobayashi, Kentaro Tanaka, Takuya H. Tatsuishi

Phys. Rev. D 98, 016004 (2018) Mar 2018

We study the lepton flavor models, whose flavor symmetries are finite
subgroups of the modular group such as and . In our models,
couplings are also nontrivial representations of these groups and modular
functions of the modulus. We stu...

We have studied four-dimensional low-energy effective field theory, derived from superstring theory, in particular heterotic string theory on the orbifolds and magnetized/intersecting brane models. We have studied Abelian and non-Abelian discrete ...

The purpose of this research is to clarify which flavor structures can be derived from superstring theory and to study their phenomenological implications.Recently, several discrete non-Abelian flavor symmetries were proposed to derive realistic m...

Understanding the origin of fermion masses and mixing angles is one of important issues in particle physics. Within the framework of supersymmetric models, a mechanism to lead to realistic Yukawa matrices, in general, affects sfermion masses as we...

Supersymmetry Breaking and Superstring Phenomenology