Yuji Omura

Moduli stabilization, F-term uplifting and soft supersymmetry breaking terms

We study moduli stabilization with F-term uplifting. As a source of uplifting F-term, we consider spontaneous supersymmetry breaking models, e.g. the Polonyi model and the Intriligator-Seiberg-Shih model. We analyze potential minima by requiring almost vanishing vacuum energy and evaluate the size of modulus F-term. We also study soft SUSY-breaking terms. In our scenario, the mirage mediation is dominant in gaugino masses. Scalar masses can be comparable with gaugino masses or much heavier, depending on couplings with spontaneous supersymmetry breaking sector.

Relaxed fine-tuning in models with nonuniversal gaugino masses

We study, in a bottom-up approach, the fine-tuning problem between soft supersymmetry (SUSY) breaking parameters and the μ term for the successful electroweak symmetry breaking in the minimal supersymmetric standard model. It is shown that certain ratios among nonuniversal gaugino masses at the grand unified theory (GUT) scale are necessary to reduce fine-tuning. In addition, when all the gaugino masses are regarded as independent ones in their origins, a small gluino mass M 3 ≤ 120 GeV and a nonvanishing A term A t ∼ O(M 3 ) associated with top squarks are also required at the GUT scale as well as the nonuniversality. On the other hand, when we consider some UV theory, which fixes ratios of soft SUSY breaking parameters as certain values aside from the overall magnitude, heavier spectra are allowed. It is favored that the gluino and W-ino masses are almost degenerate at the weak scale, while a wider region of b-ino mass is favorable.

D(4) Flavor Symmetry for Neutrino Masses and Mixing

Abstract We present the D 4 × Z 2 flavor symmetry, which is different from the previous work by Grimus and Lavoura. Our model reduces to the standard model in the low energy and there is no FCNC at the tree level. Putting the experimental data, parameters are fixed, and then the implication of our model is discussed. The condition to realize the tri-bimaximal mixing is presented. The possibility for stringy realization of our model is also discussed.

Soft supersymmetry breaking terms from D(4) x Z(2) lepton flavor symmetry

We study the supersymmetric model with D 4 × Z 2 lepton flavor symmetry. We evaluate soft supersymmetry breaking terms, i.e., soft slepton masses and A-terms, which are predicted in the D 4 flavor model. We consider constraints due to experiments of flavor-changing neutral current processes.

Flavor symmetry breaking and vacuum alignment on orbifolds

Flavor symmetry has been widely studied for figuring out the masses and mixing angles of standard model fermions. In this paper we present a framework for handling flavor symmetry breaking where the symmetry breaking is triggered by boundary conditions of scalar fields in extra-dimensional space. The alignment of scalar expectation values is achieved without referring to any details of scalar potential and its minimization procedure. As applications to non-Abelian discrete flavor symmetries, illustrative lepton mass models are constructed where the

Soft supersymmetry breaking terms from A4 lepton flavor symmetry

{S}_{3}

Dynamically sequestered F-term uplifting in extra dimension

and

Duality cascade of softly broken supersymmetric theories

{A}_{4}

Dynamical realization of democratic Yukawa matrices and alignment of A terms

flavor symmetries are broken down to the directions leading to the tribimaximal form of lepton mixing and realistic mass patterns.

R-symmetry, supersymmetry breaking and metastable vacua in global and local supersymmetric theories

We study the supersymmetric model with the A4 lepton flavor symmetry, in particular soft supersymmetry breaking terms, which are predicted from the A4 lepton flavor symmetry. We evaluate soft slepton masses and A-terms within the framework of supergravity theory. Constraints due to experiments of flavor changing neutral current processes are examined.