Language：Japanese   Publishing type：Research paper (scientific journal)  

Recent discovery of neutrino large mixings implies the large mixings in the diagonalizing matrices
of ¯5 fields in SU(5) grand unified theory (GUT), while the diagonalizing matrices of 10 fields of
SU(5) are expected to have small mixings like Cabibbo-Kobayashi-Maskawa matrix. We calculate
the predictions of flavor changing nucleon decays (FCND) in SU(5), SO(10), and E6 GUT models
which have the above features for mixings. We found that FCND can be the main decay mode and
play an important role to test GUT models.

DOI： 10.1016/j.physletb.2017.02.028

Web of Science

Web of Science

Language：Japanese  

DOI： 10.1063/1.5010112

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

We study the thermal leptogenesis in the E 6 ×U(1) A SUSY GUT model in which realistic masses and mixings of quarks and leptons can be realized. We show that the sufficient baryon number can be produced by the leptogenesis in the model, in which the mass parameter of the lightest right-handed neutrino is predicted to be smaller than 10 8 GeV. The essential point is that the mass of the lightest right-handed neutrino can be enhanced in the model because it has a lot of mass terms whose mass parameters are predicted to be the same order of magnitude which is smaller than 10 8 GeV. We show that O(10) enhancement for the lightest right-handed neutrino mass is sufficient for the observed baryon asymmetry. Note that such mass enhancements do not change the predictions of neutrino masses and mixings at the low energy scale in the E 6 model which has six right-handed neutrinos. In the calculation, we include the effects of supersymmetry and flavor in final states of the right-handed neutrino decay. We show that the effect of supersymmetry is quite important even in the strong washout regime when the effect of flavor is included. This is because the washout effects on the asymmetries both of the muon and the electron become weaker than that of the tau asymmetry.

DOI： 10.1007/JHEP02(2016)108

arXiv

Language：English   Publishing type：Research paper (scientific journal)  

Particle production caused by the oscillation after inflation is important since it explains reheating after inflation. On the particle theory side, we know that effective action may have additional higher dimensional terms (usually called nonrenormalizable terms) suppressed by the cutoff scale. Moreover, interaction between the inflaton and so-called moduli field will be higher dimensional. Therefore, if such higher dimensional interaction is significant for resonant particle production, one cannot avoid the effect in a preheating study. We explicitly calculated the required number of oscillations for the energy transfer. Consequently, cosmological history of an oscillating field and the moduli problem can be reconsidered.

DOI： 10.1103/PhysRevD.91.103504

Language：English   Publishing type：Research paper (scientific journal)  

We show that the sizable D-term contributions to sfermion mass spectrum can be signatures of certain GUT, E6×SU(2)F×U(1)A GUT. Note that these D-term contributions deviate the degenerate sfermion masses among different generations in this model. This is different from the previous works which have argued the D-term contributions, which deviate masses only between sfermions with different quantum charges, as a signature of GUT with larger rank unification group. Such D-terms are strongly constrained by the FCNC processes if the SUSY breaking scale is the weak scale. However, in E6×SU(2)F×U(1)A, natural SUSY type sfermion mass spectrum is obtained, and if the masses of 103 sfermions are larger than O(1TeV) to realize 126 GeV Higgs and the other sfermion masses are O(10TeV), then sizable D-term contribution is allowed. If the deviations by these D-terms can be observed in future experiments like 100 TeV proton collider or muon collider, we may confirm the E6×SU(2)F×U(1)A GUT.

DOI： 10.1093/ptep/ptu151

Language：English   Publishing type：Research paper (scientific journal)  

We consider the situation in which m_{3/2}\sim O(100{\rm TeV}) for solving the gravitino problem and the other supersymmetry(SUSY) breaking parameters are O(1{\rm TeV}) for the naturalness. We point out that the anomaly mediation cancels out the renormalization group contribution to the gaugino masses and the sfermion masses other than the stop masses at a scale which is called the mirage scale. The situation is similar to the mirage mediation, in which special boundary conditions for the SUSY breaking parameters are required, though for the stop masses and the up-type Higgs mass, such cancellation at the mirage scale does not happen. Despite no cancellation for the up-type Higgs mass, we show that the little hierarchy problem becomes less severe in this situation. One advantage of this situation over the mirage mediation is that the stop mixing parameter A_t can be larger and therefore, smaller stop mass is sufficient for 125 GeV Higgs. When the mirage scale is around TeV scale, the SUSY breaking parameters induced by the gravity mediation at the grand unification scale can be observed directly by the TeV scale experiments.

DOI： DOI:10.1093/ptep/ptu118

Language：English   Publishing type：Research paper (scientific journal)  

Nucleon lifetimes for various decay modes via dimension 6 operators are calculated in the anomalous U(1)_A GUT scenario, in which the unification scale \Lambda_u becomes smaller than the usual suersymmetric (SUSY) unification scale \Lambda_G=2\times 10^{16} GeV in general. Since the predicted lifetime \tau(p \rightarrow \pi^0 + e^c) becomes around the experimental lower bound though it is strongly dependent on the explicit models, the discovery of the nucleon decay in near future can be expected. We explain why the two ratios R_1 \equiv \Gamma_{n \rightarrow \pi^0 + \nu^c}/\Gamma_{p \rightarrow \pi^0 + e^c} and R_2 \equiv \Gamma_{p \rightarrow K^0 + \mu^c}/\Gamma_{p \rightarrow \pi^0 + e^c} are important in identifying grand unification group and we show that three anomalous U(1)_A SUSY GUT models with SU(5), SO(10) and E_6 grand unification group can be identified by measuring the two ratios. If R_1 is larger than 0.4, the grand unification group is not SU(5), and moreover if R_2 is larger than 0.3, the grand unification group is implied to be E_6.

DOI： 10.1103/PhysRevD.88.095008

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/PhysRevD.83.091703

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

It has been pointed out that in E6 grand unified theory with SU(2) family symmetry, the spontaneous CP violation can solve the supersymmetric CP problem. The scenario predicts V_{ub} \sim O(\lambda^4) rather than O(\lambda^3) which is naively expected value, because of a cancellation at the leading order. Since the experimental value of V_{ub} is O(\lambda^4), it must be important to consider the reason and the conditions for the cancellation. In this paper, we give a simple reason for the cancellation and show that in some E6 models such a cancellation requires that the vacuum expectation value (VEV) of the adjoint Higgs does not break U(1)_{B-L}. Note that this direction of the VEV plays an important role in solving the doublet-triplet splitting problem by Dimopoulos-Wilczek mechanism. In this E6 models, the experiments may measure the direction of the adjoint Higgs VEV by measuring the size of V_{ub} \sim O(\lambda^4).

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

We showed that in E6 grand unified theory with family symmetry, spontaneous CP violation can not only solve the SUSY CP problem but also realize reasonable Kabayashi-Maskawa phase. I think that this scenario is one of the most promizing scenario which explains the origin of the Kobayashi-Maskawa matrix.

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

In E6 grand unified theory with horizontal symmetry, a specific sfermion mass spectrum is predicted. In this paper, we calculated the lepton flavor violation processes predicted by the sfermion mass spectrum. We pointed out that tau->mu gamma can be observed in (super) B factory and mu-> e gamma in MEG experiment.

Language：English   Publishing type：Research paper (scientific journal)  

When the standard model Higgs mass bound obtained by LEP is applied to the Higgs in supersymmetric models, the electroweak scale becomes unstable because of the large stop mass. This is called the little hierarchy problem. We pointed out that in the minimal supersymmetric standard model, there is a parameter region in which the coupling between the lightest higgs and Z boson becomes smaller than in the standard model and the higgs mass bound cannot be applied. We also pointed out that in the parameter region, all the Higgs bosons become light, but the contribution to the b->s gamma process can be cancelled by supersymmetric contribution.

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Event date： 2018.12

Language：English   Presentation type：Oral presentation (general)  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (keynote)  

Venue：坂出   Country：Japan  

Event date： 2018.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Tianjin  

Event date： 2018.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Barcellona   Country：Spain  

Event date： 2017.7

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：KEK つくば   Country：Japan  

Event date： 2017.5

Language：English   Presentation type：Oral presentation (invited, special)  

Venue：Cleveland   Country：United States  

Event date： 2016.12

Language：English   Presentation type：Oral presentation (general)  

Venue：J-Parc, Tokai, Ibaragi   Country：Japan  

Event date： 2016.6 - 2016.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Deadwood, South Dakoda, USA   Country：United States  

Event date： 2015.10

Language：English   Presentation type：Oral presentation (general)  

Venue：Stony Brook, USA   Country：United States  

Event date： 2015.8

Language：English   Presentation type：Oral presentation (general)  

Venue：J-Parc, Tokai, Ibaragi, Japan   Country：Japan  

Event date： 2007.3

Language：English   Presentation type：Oral presentation (general)  

Event date： 2006.12

Language：English  

Country：Japan  

Event date： 2006.9

Language：English  

Country：Japan  

Event date： 2006.6

Language：English  

大統一理論の基礎を説明し、3つの力を統一するだけでなく、クォーク、レプトンも統一することを示す。また、それぞれの統一に対して実験からのサポートがあることを学ぶ。