We complete the four-dimensional N = 1 superfield description of sixdimensional supergravity. The missing ingredients in the previous works are the superfields that contain the sechsbein e(4)((v) under bar), e(5)((v) under bar), e(mu)((4) under bar), e(mu)((5) under bar) and the second gravitino. They are necessary to make the action invariant under the diffeomorphisms and the Lorentz transformations involving the extra dimensions. We find the corresponding superfield transformation laws, and show the invariance of the action under them. We also check that the resultant action reproduces the known superfield description of five-dimensional supergravity through the dimensional reduction.

We study Kahler moduli stabilizations in semirealistic magnetized D-brane models based on Z(2) x Z'(2) toroidal orbifolds. In type IIB compactifications, 3-form fluxes can stabilize the dilaton and complex structure moduli fields, but there remain some massless closed string moduli fields, Kahler moduli. The magnetic fluxes generate Fayet-Iliopoulos terms, which can fix ratios of Kahler moduli. On top of that, we consider D-brane instanton effects to stabilize them in concrete D-brane models and investigate the brane configurations to confirm that the moduli fields can be stabilized successfully. In this paper, we treat two types of D-brane models. One is based on D9-brane systems respecting the Pati-Salam model. The other is realized in a D7-brane system breaking the Pati-Salam gauge group. We find suitable configurations where the D-brane instantons can stabilize the moduli fields within both types of D-brane models, explaining an origin of a small constant term of the superpotential, which is a key ingredient for successful moduli stabilizations.

We study supersymmetric (SUSY) models derived from the ten-dimensional SUSY Yang-Mills theory compactified on magnetized orbifolds, with nonvanishing Fayet-Iliopoulos (FI) terms induced by magnetic fluxes in extra dimensions. Allowing the presence of FI- terms relaxes a constraint on flux configurations in SUSY model building based on magnetized backgrounds. In this case, charged fields develop their vacuum expectation values to cancel the FI- terms in the D-flat directions of fluxed gauge symmetries, which break the gauge symmetries and lead to a SUSY vacuum. Based on this idea, we propose a new class of SUSY magnetized orbifold models with three generations of quarks and leptons. Especially, we construct a model where the right-handed sneutrinos develop their vacuum expectation values which restore the supersymmetry but yield lepton number violating terms below the compactification scale, and show their phenomenological consequences.

We study the flavor structure in SO(32) heterotic string theory on six-dimensional tori with magnetic fluxes. Specifically, we focus on models with the flavor symmetries SU(3)(f) and Delta(27). In both models, we can realize the realistic quark masses and mixing angles.

We construct several dynamical supersymmetry breaking (DSB) models within a single ten-dimensional supersymmetric Yang-Mills (SYM) theory, compactified on magnetized tori with or without orbifolding. We study the case that the supersymmetry breaking is triggered by a strong dynamics of SU(NC) SYM theory with N-F flavors contained in the four-dimensional effective theory. We show several configurations of magnetic fluxes and orbifolds, those potentially yield, below the compactification scale, the field contents and couplings required for triggering DSB. We especially find a class of self-complete DSB models on orbifolds, where all the extra fields are eliminated by the orbifold projection and DSB successfully occurs within the given framework. Comments on some perspectives for associating the obtained DSB models with the other sectors, such as the visible sector and another hidden sector for, e.g., stabilizing moduli, are also given. (C) 2016 The Authors. Published by Elsevier B.V.

We study wavefunctions on D7-branes with magnetic fluxes in the conifold. Since some supersymmetric embeddings of D- branes on the AdS(5) x T-1,T-1 geometry are known, we consider one of the embeddings, especially the spacetime filling D7-branes in which (a part of) the standard model is expected to be realized. The explicit form of induced metric on the D7-branes allows us to solve the Laplace and Dirac equations to evaluate matter wavefunctions in extra dimensions analytically. We find that the zeromode wavefunctions can be localized depending on the configuration of magnetic fluxes on D7-branes, and show some phenomenological aspects.

We study SO(32) heterotic string theory on a torus with magnetic fluxes. Non-vanishing fluxes can lead to non-universal gauge kinetic functions for SU(3) x SU(2) x U(1)gamma, which is an important feature of SO(32) heterotic string theory in contrast to the E-8 x E-8 theory. It is found that the experimental values of gauge couplings are realized with O(1) values of moduli fields based on realistic models with the SU(3) x SU(2) x U(1)gamma gauge symmetry and three chiral generations of quarks and leptons without chiral exotics.

We provide a systematic way of dimensional reduction for (4 + 2n)-dimensional U(N) supersymmetric Yang-Mills (SYM) theories (n = 0, 1, 2, 3) and their mixtures compactified on two-dimensional tori with background magnetic fluxes, which preserve a partial N = 1 supersymmetry out of full N = 2, 3 or 4 in the original SYM theories. It is formulated in an N = 1 superspace respecting the unbroken supersymmetry, and the four-dimensional effective action is written in terms of superfields representing N = 1 vector and chiral multiplets, those arise from the higher-dimensional SYM theories. We also identify the dilaton and geometric moduli dependence of matter Kahler metrics and superpotential couplings as well as of gauge kinetic functions in the effective action. The results would be useful for various phenomenological/cosmological model buildings with SYM theories or D-branes wrapping magnetized tori, especially, with mixture configurations of them with different dimensionalities from each other. (C) 2015 The Authors. Published by Elsevier B.V.

Abstract: We express the action of six-dimensional supergravity in terms of four-dimensional N=1$$ \\mathcal{N}=1 $$ superfields, focusing on the moduli dependence of the action. The gauge invariance of the action in the tensor-vector sector is realized in a quite nontrivial manner, and it determines the moduli dependence of the action. The resultant moduli dependence is intricate, especially on the shape modulus. Our result is reduced to the known superfield actions of six-dimensional global SUSY theories and of five-dimensional supergravity by replacing the moduli superfields with their background values and by performing the dimensional reduction, respectively.

We search for realistic supersymmetric standard-like models from SO(32) heterotic string theory on factorizable tori with multiple magnetic fluxes. Three chiral ganerations of quarks and leptons are derived from the adjoint and vector representations of SO(12) gauge groups embedded in SO(32) adjoint representation. Massless spectra of our models also include Higgs fields, which have desired Yukawa couplings to quarks and leptons at the tree-level.

© 2015, The Author(s). Abstract: We search for realistic supersymmetric standard-like models from SO(32) heterotic string theory on factorizable tori with multiple magnetic fluxes. Three chiral ganerations of quarks and leptons are derived from the adjoint and vector representations of SO(12) gauge groups embedded in SO(32) adjoint representation. Massless spectra of our models also include Higgs fields, which have desired Yukawa couplings to quarks and leptons at the tree-level.

Abstract: In this letter, we study collider phenomenology in the supersymmetric Standard Model with a certain type of non-universal gaugino masses at the gauge coupling unification scale, motivated by the little hierarchy problem. In this scenario, especially the wino mass is relatively large compared to the gluino mass at the unification scale, and the heavy wino can relax the fine-tuning of the higgsino mass parameter, so-called μ-parameter. Besides, it will enhance the lightest Higgs boson mass due to the relatively large left-right mixing of top squarks through the renormalization group (RG) effect. Then 125 GeV Higgs boson could be accomplished, even if the top squarks are lighter than 1 TeV and the μ parameter is within a few hundreds GeV. The right-handed top squark tends to be lighter than the other sfermions due to the RG runnings, then we focus on the top squark search at the LHC. Since the top squark is almost right-handed and the higgsinos are nearly degenerate, 2b + ET miss channel is the most sensitive to this scenario. We figure out current and expected experimental bounds on the lightest top squark mass and model parameters at the gauge coupling unification scale.

We construct the Dirac-Born-Infeld action in the context of N=1 conformal supergravity and its possible extensions including matter couplings. We especially focus on the Volkov-Akulov constraint, which is important to avoid ghost modes from the higher derivative terms. In the case with matter couplings, we find the modified D-term potential.

We study the μ-term matrix of Higgs pairs induced by the D-brane instanton effects in intersecting D6-brane models compactified on T6. It is found that the μ-term matrix has a certain permutation symmetry and its eigenvalues have large hierarchical structure without fine-tuning.

We construct the Dirac-Born-Infeld action in the context of N = 1 conformal supergravity and its possible extensions including matter couplings. We especially focus on the Volkov-Akulov constraint, which is important to avoid ghost modes from the higher derivative terms. In the case with matter couplings, we find the modified D-term potential.

We study the mu-term matrix of Higgs pairs induced by the D-brane instanton effects in intersecting D6-brane models compactified on T-6. It is found that the mu-term matrix has a certain permutation symmetry and its eigenvalues have large hierarchical structure without fine-tuning.

We investigate the inflation model with a massive vector multiplet in a case that the action of the vector multiplet is extended to the Dirac-Born-Infeld (DBI) type one. We show the massive DBI action in four-dimensional N = 1 supergravity and find that the higher-order corrections associated with the DBI extension make the scalar potential flat with a simple choice of the matter couplings. We also discuss the DBI extension of the new minimal Starobinsky model and find that it is dual to a special class of the massive DBI action.

We propose natural inflation from the heterotic string theory on the "Swiss-Cheese" Calabi-Yau manifold with multiple U(1) magnetic fluxes. Such multiple U(1) magnetic fluxes stabilize the same number of the linear combination of the universal axion and Kahler axions, and one of the Kahler axions is identified as the inflaton. This axion decay constant can be determined by the size of one-loop corrections to the gauge kinetic function of the hidden gauge groups, which leads effectively to the trans-Planckian axion decay constant consistent with the Planck data. During the inflation, the real parts of the moduli are also stabilized by employing the nature of the "Swiss-Cheese" Calabi-Yau manifold.

We propose a mechanism for the natural inflation with and without modulation in the framework of type IIB string theory on toroidal orientifold or orbifold. We explicitly construct the stabilization potential of complex structure, dilaton and Kahler moduli, where one of the imaginary component of complex structure moduli becomes light which is identified as the inflaton. The inflaton potential is generated by the gaugino-condensation term which receives the one-loop threshold corrections determined by the field value of complex structure moduli and the axion decay constant of inflaton is enhanced by the inverse of one-loop factor. We also find the threshold corrections can also induce the modulations to the original scalar potential for the natural inflation. Depending on these modulations, we can predict several sizes of tensor-to-scalar ratio as well as the other cosmological observables reported by WMAP, Planck and/or BICEP2 collaborations.

We express supersyrnmetric couplings among the vector and the tensor multiplets in six dimensions (6D) in terms of N = 1 superfields. The superfield description is derived from the invariant action in the projective superspace. The obtained expression is consistent with the known superfield actions of 6D supersymmetric gauge theory and 5D Chern-Simons theory after the dimensional reduction. Our result provides a crutial clue to the N = 1 superfield description of 6D supergravity.

We consider the supersymmetry breaking effects on typical inflation models with different types of Kahler potential. The critical size of supersymmetry-breaking scale, above which the flatness of the inflaton potential is spoiled, drastically changes model by model. We present the universal description of such effects in terms of a field-dependent scaling factor by which gravity-mediated supersymmetry breaking terms are suppressed or enhanced, based on the conformal supergravity framework. Such a description would be useful when we estimate them in constructing supersymmetric models of particle cosmology.

We propose a simple,. but effective mechanism to realize an inflationary earl universe consistent with the observed WMAP, Planck and/or BICEP2 data, which would be incorporated in various supersymmetric models of elementary particles constructed in the (effective) five-dimensional spacetime. In our scenario, the inflaton field is identified with one of the moduli appearing when the fifth direction is compactified, and a successful cosmological inflation without the so-called eta problem can be achieved by a very simple moduli stabilization potential. We also discuss the related particle cosmology during and (just) after the inflation, such as the (no) cosmological moduli problem.

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 Cabibbo-Kobayashi-Maswaka (CKM) mixing angles, even with a small number of tunable parameters and without any critical fine-tuning. As a reason behind this, we find that the obtained Yukawa matrices possess a Froggatt-Nielsen-like structure with Gaussian hierarchies, which provides a suitable texture for them favored by the experimental data.

We study the Higgs boson mass and the spectrum of supersymmetric (SUSY) particles in the wellmotivated particle physics model derived from a ten-dimensional supersymmetric Yang Mills theory compactified on three factorizable tori with magnetic fluxes. This model was proposed in a previous work, where the flavor structures of the standard model including the realistic Yukawa hierarchies are obtained from non-hierarchical input parameters on the magnetized background. Assuming moduli- and anomaly-mediated contributions dominate the soft SUSY breaking terms, we study the precise SUSY spectra and analyze the Higgs boson mass in this mode, which are compared with the latest experimental data. (C) 2014 The Authors. Published by Elsevier B.V.

We study the mass of the lightest CP-even Higgs boson in the deflected mirage mediation that is a quite general framework of the mediation of supersymmetry breaking, incorporating the case where all of the modulus-, the anomaly-and the gauge-mediated contributions to the soft supersymmetry breaking parameters become sizable. We evaluate the degree of tuning the so-called parameter required for realizing a correct electroweak symmetry breaking and study how to accomplish both the observed Higgs boson mass and the relaxed fine-tuning. We identify the parameter space favored from such a perspective and show the superparticle mass spectrum with some input parameters inside the indicated region. The results here would be useful when we aim to prove the communication between the visible and the hidden sectors in supergravity and superstring models based on the recent observations.

We study discrete flavor symmetries of the models based on a ten-dimensional supersymmetric Yang-Mills (10D SYM) theory compactified on magnetized tori. We assume non-vanishing non-factorizable fluxes as well as the orbifold projections. These setups allow model-building with more various flavor structures. Indeed, we show that there exist various classes of non-Abelian discrete flavor symmetries. In particular, we find that S-3 flavor symmetries can be realized in the framework of the magnetized 10D SYM theory for the first time.

We study the flavor landscape of the visible sector of particle physics models based on a ten-dimensional super Yang-Mills theory compactified on magnetized tori preserving four-dimensional Nu = 1 supersymmetry. Recently, we constructed a semirealistic model which contains the minimal supersymmetric standard model (MSSM) using an ansatz of magnetic fluxes and orbifolding projections. However, we can consider more various configurations of magnetic fluxes and orbifolding projections preserving fourdimensional N = 1 supersymmetry. We research systematically such possibilities for leading to MSSM-like models and study their phenomenological aspects.

We present a particle physics model based on a ten-dimensional (10D) super Yang-Mills (SYM) theory compactified on magnetized tori preserving four-dimensional N = 1 supersymmetry. The low-energy spectrum contains the minimal supersymmetric standard model with hierarchical Yukawa couplings caused by a wavefunction localization of the chiral matter fields due to the existence of magnetic fluxes, allowing a semi-realistic pattern of the quark and the lepton masses and mixings. We show supersymmetric flavor structures at low energies induced by a moduli-mediated and an anomaly-mediated supersymmetry breaking. (C) 2013 Elsevier B.V. All rights reserved.

We identify a parameter region where the mass of the lightest CP-even Higgs boson resides at 124.4-126.8 GeV, and at the same time the degree of tuning a Higgsino-mass parameter (the so-called mu-parameter) is relaxed above 10% in the minimal supersymmetric standard model (MSSM) with soft supersymmetry breaking terms, by solving the full set of one-loop renormalization group equations numerically. It is found that certain nonuniversal values of gaugino-mass parameters at the so-called grand unification theory (GUT) scale similar to 10(16) GeV are important ingredients for the MSSM to predict, without severe fine-tuning, the Higgs boson mass similar to 125 GeV, indicated by recent observations at the Large Hadron Collider. We also show a typical superparticle spectrum in this parameter region.

We present a four-dimensional (4D) N = 1 superfield description of supersymmetric Yang-Mills (SYM) theory in ten-dimensional (10D) spacetime with certain magnetic fluxes in compactified extra dimensions preserving partial N = 1 supersymmetry out of full N = 4. We derive a 41) effective action in N = 1 superspace directly from the 10D superfield action via dimensional reduction, and identify its dependence on dilaton and geometric moduli superfields. A concrete model for three generations of quark and lepton superfields are also shown. Our formulation would be useful for building various phenomenological models based on magnetized SYM theories or D-branes. (C) 2012 Elsevier B.V. All rights reserved.

We perform a comprehensive and systematic analysis of the SUSY flavor structure of generic 5D supergravity models on S-1/Z(2) with multiple Z(2)-odd vector multiplets that generate multiple moduli. The SUSY flavor problem can be avoided due to contact terms in the 4D effective Kahler potential peculiar to the multi-moduli case. A detailed phenomenological analysis is provided based on an illustrative model.

We study non-Abelian flavor symmetries on orbifolds, S-1/Z(2) and T-2/Z(3). Our extra dimensional models realize D-N, Sigma(2N(2)), Delta(3N(2)) and Delta(6N(2)) including A(4) and S-4. In addition, one can also realize their subgroups such as Q(N), T-7, etc. The S-3 flavor symmetry can be realized on both S-1/Z(2) and T-2/Z(3) orbifolds.

We study the flavor structure of four-dimensional (4D) effective theories, which are derived from extra dimensional theories with magnetic fluxes and non-Abelian Wilson lines. We study zero-mode wave functions in generic case and compute Yukawa couplings as well as four-point couplings. In our models, we also discuss non-Abelian discrete flavor symmetries such as D-4, Delta(27), and Delta(54). The orbifold background is also studied.

We study torus/orbifold models with magnetic flux and Wilson line backgrounds. The number of zero modes and their profiles depend on those backgrounds. That has interesting implications from the viewpoint of particle phenomenology.

We study non-Abelian discrete flavor symmetries, which appear in magnetized brane models. For example, D-4, Delta(27) and Delta(54) flavor symmetries can appear with matter fields in several representations. We also study the orbifold background, where non-Abelian flavor symmetries are broken in a certain way. (C) 2009 Published by Elsevier B.V.

We study three generation models in the four-dimensional spacetime, which can be derived from the ten-dimensional N = 1 super-Yang-Mills theory on the orbifold background with a non-vanishing magnetic flux. We classify the flavor structures and show possible patterns of Yukawa matrices. Some examples of numerical studies are also shown. (C) 2009 Elsevier B.V. All rights reserved.

We compute three-point and higher order couplings in magnetized brane models. We show that higher order couplings are written as products of three-point couplings. This behavior is the same as higher order amplitudes by conformal field theory calculations e. g. in intersecting D-brane models.

We study five-dimensional supergravity on S1/Z2 with a physical Z2-odd vector multiplet, which yields an additional modulus other than the radion. We derive four-dimensional effective theory and find additional terms in the Kähler potential that are peculiar to the multi-moduli case. Such terms can avoid tachyonic soft scalar masses at tree level, which are problematic in the single modulus case. We also show that the flavor structure of the soft terms are different from that in the single modulus case when hierarchical Yukawa couplings are generated by wave function localization in the fifth dimension. We present a concrete model that stabilizes the moduli at a supersymmetry breaking Minkowski minimum and show the low-energy sparticle spectrum. © 2009 The American Physical Society.

We study the duality cascade of softly broken supersymmetric theories. We investigate the renormalization group (RG) flow of SUSY breaking terms as well as supersymmetric couplings. It is found that the magnitudes of SUSY breaking terms are suppressed in most regimes of the RG flow through the duality cascade. At one stage of cascading, the gaugino mass of the strongly coupled sector and scalar masses converge to certain values, which are determined by the gauge coupling and the gaugino mass of the weakly coupled sector. At the next stage, the strongly and weakly coupled sectors are interchanged with each other. We also show the possibility that cascading would be terminated by the gauge symmetry breaking, which is induced by the so-called B-term.

We study five-dimensional supergravity on S-1/Z(2) with a physical Z(2)-odd vector multiplet, which yields an additional modulus other than the radion. We derive four-dimensional effective theory and find additional terms in the Kahler potential that are peculiar to the multi-moduli case. Such terms can avoid tachyonic soft scalar masses at tree level, which are problematic in the single modulus case. We also show that the flavor structure of the soft terms are different from that in the single modulus case when hierarchical Yukawa couplings are generated by wave function localization in the fifth dimension. We present a concrete model that stabilizes the moduli at a supersymmetry breaking Minkowski minimum and show the low-energy sparticle spectrum.

We study five-dimensional supergravity on S-1 Z(2) with a physical Z(2)-odd vector multiplet, which yields an additional modulus other than the radion We find additional terms in the 4-dimensional effective theory that are peculiar to the multi moduli case Such terms can make the soft masses are non-tachyonic and almost flavor-universal at tree-level, in contrast to the single modulus case This provides a new possibility to solve the SUSY flavor problem

We study (4+2n)-dimensional N=1 super Yang-Mills theory on the orbifold background with non-vanishing magnetic fluxes. In particular, we study zero- modes of spinor fields. The flavor structure of our models is different from one in magnetized torus models, and would be interesting in realistic model building.

We study nonperturbative moduli superpotentials with positive exponents, i.e. the form like Ae(aT) with a positive constant a and the modulus T. These effects can be generated, e.g., by D-branes which have negative Ramond-Ramond charge of the lower-dimensional D-brane. The scalar potentials including such terms have quite a rich structure. There are several local minima with different potential energies and a high barrier, whose height is of O(M-p(4)). We discuss their implications from the viewpoints of cosmology and particle phenomenology, e.g. the realization of inflation models, avoiding the overshooting problem. This type of potential would be useful to realize the inflation and low-energy supersymmetry breaking.

We study a four-dimensional effective theory of the five-dimensional (5D) gauged supergravity with a universal hypermultiplet and perturbative superpotential terms at the orbifold fixed points. Among eight independent isometrics of the scalar manifold, we focus on three directions for gauging by the graviphoton. The class of models we consider includes the 5D heterotic M-theory and the supersymmetric Randall-Sundrum model as special limits of the gauging parameters. We analyze the vacuum structure of such models, especially the nature of moduli stabilization, from the viewpoint of the effective theory. We also discuss the uplifting of supersymmetric anti-de Sitter vacua. (c) 2007 Elsevier B.V. All rights reserved.

We study moduli stabilization, the dynamical supersymmetry (SUSY) breaking, the uplifting of SUSY anti-de Sitter (AdS) vacuum and the sequestering of hidden sector in a five-dimensional supergravity model, where all modes of the visible sector and the hidden sector are originated from bulk fields. We clarify couplings between the visible and hidden sectors. The expressions for the visible sector soft SUSY breaking terms as well as the hidden sector potential are shown explicitly in our model. The sequestering is achieved dynamically by a wavefunction localization in extra dimension. We find that the tree-level soft scalar mass and the A-term can be suppressed at a SUSY breaking Minkowski minimum where the radius modulus is stabilized, while gaugino masses would be a mirage type.

We study the scenario that conformal dynamics leads to metastable supersymmetry breaking vacua. At a high energy scale, the superpotential is not R-symmetric and has a supersymmetric minimum. However, conformal dynamics suppresses several operators along renormalization group flow toward the infrared fixed point. Then we can find an approximately R-symmetric superpotential, which has a metastable supersymmetry breaking vacuum, and the supersymmetric vacuum moves far away from the metastable supersymmetry breaking vacuum. We show a 4D simple model. Furthermore, we can construct 5D models with the same behavior, because of the AdS/CFT duality.

We investigate 5-dimensional supergravity on S-1/Z(2) with a physical Z(2)-odd vector multiplet, which yields an additional modulus other than the radion. We find additional terms in the 4-dimensional effective theory that are peculiar to the multi moduli case. Such terms can make the soft masses are non-tachyonic and almost flavor-universal at tree-level, in contrast to the single modulus case. This provides a new possibility to solve the SUSY flavor problem.

We present a systematic. way for deriving a four-dimensional(4D) effective action of the five-dimensional(5D) orbifold supergravity respecting the N=1 off-shell structure. As an illustrating example, we derive a 4D effective theory of the 5D gauged supergravity with a universal hypermultiplet and generic gaugings, which includes the 5D heterotic Mtheory and the supersymmetric Randall-Sundrum model as special limits of the gauging parameters. We show the vacuum structure of such model, especially the nature of moduli stabilization, introducing perturbative superpotential terms at the orbifold fixed points.

We discuss the nature of sequestering supersymmetry breaking sectors in a certain class of moduli stabilization in supergravity/string models, where a negative vacuum energy of the nonperturbative moduli potential is canceled by dynamically generated F-terms. Two illustrating examples are shown to sketch the issues around the supersymmetry breaking, flavors and sequestering within such a framework.

We study moduli stabilization and a realization of de Sitter vacua in generalized F-term uplifting scenarios of the Kachru-Kallosh-Linde-Trivedi-type anti-de Sitter vacuum, where the uplifting sector X directly couples to the light Kahler modulus T in the superpotential through, e.g., stringy instanton effects. F-term uplifting can be achieved by a spontaneous supersymmetry breaking sector, e.g., the Polonyi model, the O'Raifeartaigh model, and the Intriligator-Seiberg-Shih model. Several models with the X-T mixing are examined, and qualitative features in most models even with such mixing are almost the same as those in the Kachru-Kallosh-Linde-Trivedi scenario. One of the quantitative changes, which are relevant to the phenomenology, is a larger hierarchy between the modulus mass m(T) and the gravitino mass m(3/2), i.e., m(T)/m(3/2)=O(a(2)), where a similar to 4 pi(2). In spite of such a large mass, the modulus F term is suppressed not like F-T=O(m(3/2)/a(2)), but like F-T=O(m(3/2)/a) for ln(M-Pl/m(3/2))similar to a, because of an enhancement factor coming from the X-T mixing. Then we typically find a mirage-mediation pattern of gaugino masses of O(m(3/2)/a), while the scalar masses would be generically of O(m(3/2)).

We study N=1 global and local supersymmetric theories with a continuous global U(1)(R) symmetry as models of dynamical supersymmetry (SUSY) breaking. We introduce explicit R-symmetry breaking terms into such models, in particular a generalized O'Raifeartaigh model. Such explicit R-symmetry breaking terms can lead to a SUSY preserving minimum. We classify explicit R-symmetry breaking terms by the structure of newly appeared SUSY stationary points as a consequence of the R-breaking effect, which could make the SUSY breaking vacuum metastable. We show that the R-breaking terms are basically divided into two categories. One of them does not generate a SUSY solution, or yields SUSY solutions that disappear in the case of supergravity when we tune a parameter so that the original SUSY breaking minimum becomes a Minkowski vacuum. We also show that the general argument by Nelson and Seiberg for a dynamical SUSY breaking still holds with a local SUSY except for a certain nontrivial case, and present concrete examples of the exception.

We study the TeV scale partial mirage unification scenario, where the gluino and wino masses are degenerate around a TeV scale, but the bino mass is not degenerate. This scenario has phenomenologically interesting aspects. First, because of the degeneracy between the gluino and wino masses, this scenario does not have the little hierarchy problem, that is, the higgisino mass is around 150 GeV. The lightest superparticle is a mixture of the bino and higgsino, and can lead to a right amount of thermal relic density as a dark matter candidate.

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 M3 120GeV and a nonvanishing A term At∼O(M3) 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. © 2007 The American Physical Society.

We study, in a bottom-up approach, the fine-tuning problem between soft supersymmetry (SUSY) breaking parameters and the mu 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 less than or similar to 120 GeV and a nonvanishing A term A(t)similar to 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.

We study the five-dimensional (5D) supergravity compactified on an orbifold S-1/Z(2), where the U(1)(R) symmetry is gauged by the graviphoton with Z(2)-even coupling. In contrast to the case of gauging with Z(2)-odd coupling, this class of models has Majoranatype masses and allows the Scherk-Schwarz ( SS) twist even in the warped spacetime. Starting from the off-shell formulation, we show that the supersymmetry is always broken in an orbifold slice of AdS(5), irrespective of the value of the SS twist parameter. We analyze the spectra of gaugino and gravitino in such background, and find the SS twist can provide sizable effects on them in the small warping region.

We reinterpret the Scherk-Schwarz (SS) boundary condition for SU(2) R in a compactified five-dimensional (5D) Poincaré supergravity in terms of the twisted SU(2)U gauge fixing in 5D conformal supergravity. In such translation, only the compensator hypermultiplet is relevant to the SS twist, and various properties of the SS mechanism can be easily understood. Especially we show the correspondence between the SS twist and boundary constant superpotentials within our framework. © 2007 American Institute of Physics.

We discuss the dimensional reduction of five-dimensional supergravity compactified on S1/Z2 keeping the N=1 off-shell structure. In particular, we clarify the roles of the Z2-odd N=1 multiplets in such an off-shell dimensional reduction. Their equations of motion provide constraints on the Z2-even multiplets and extract the zero modes from the latter. The procedure can be applied to a wide range of models and performed in a background-independent way. We demonstrate it in some specific models. © 2007 The American Physical Society.

We show some structures of moduli stabilization and supersymmetry breaking caused by gaugino condensations with the gauge couplings depending on two moduli which often appear in the four-dimensional effective theories of superstring compactifications. © 2007 American Institute of Physics.

We show some structures of moduli stabilization and supersymmetry breaking caused by gaugino condensations with the gauge couplings depending on two moduli which often appear in the four-dimensional effective theories of superstring compactifications.

We show some structures of moduli stabilization and supersymmetry breaking caused by gaugino condensations with the gauge couplings depending on two moduli which often appear in the four-dimensional effective theories of superstring compactifications.

We discuss the dimensional reduction of five-dimensional supergravity compactified on S-1/Z(2) keeping the N=1 off-shell structure. In particular, we clarify the roles of the Z(2)-odd N=1 multiplets in such an off-shell dimensional reduction. Their equations of motion provide constraints on the Z(2)-even multiplets and extract the zero modes from the latter. The procedure can be applied to a wide range of models and performed in a background-independent way. We demonstrate it in some specific models.

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.

We study two steps of moduli stabilization in type IIB flux compactification with gaugino condensations. We consider the condition that one can integrate out heavy moduli first with light moduli remaining. We give appendix, where detail study is carried out for potential minima of the model with a six dimensional compact space with h(1,1)=h(2,1)=1, including the model, whose respective moduli with h(1,1),h(2,1)not equal 1 are identified.

There are some points to notice in the dimensional reduction of off-shell supergravity. We discuss a consistent way of dimensional reduction of five-dimensional off-shell supergravity compactified on S-1/Z(2). There are two approaches to the four-dimensional effective action, which are complementary to each other. Their essential difference is the treatment of the compensator and the radion superfields. We explain these approaches in detail and examine their consistency. Comments on related works are also provided.

We study supersymmetric models with double gaugino condensations in the hidden sector, where the gauge couplings depend on two light moduli of superstring theory. We perform a detailed analysis of this class of model and show that there is no stable supersymmetric minimum with finite vacuum values of moduli fields. Instead, we find that the supersymmetry breaking occurs with moduli stabilized and negative vacuum energy. That yields moduli-dominated soft supersymmetry breaking terms. To realize slightly positive (or vanishing) vacuum energy, we add uplifting potential. We discuss uplifting does not change qualitatively the vacuum expectation values of moduli and the above feature of supersymmetry breaking. (c) 2006 Elsevier B.V. All rights reserved.

We study KKLT type models with moduli-mixing superpotential. In several string models, gauge kinetic functions are written as linear combinations of two or more moduli fields. Their gluino condensation generates moduli-mixing superpotential. We assume one of moduli fields is frozen already around the string scale. It is found that Kahler modulus can be stabilized at a realistic value without tuning 3-form fluxes because of gluino condensation on (non-)magnetized D-brane. Furthermore, we do not need to highly tune parameters in order to realize a weak gauge coupling and a large hierarchy between the gravitino mass and the Planck scale, when there exists nonperturbative effects on D3-brane. SUSY breaking patterns in our models have a rich structure. Also, some of our models have cosmologically important implications, e.g., on the overshooting problem and the destabilization problem due to finite temperature effects as well as the gravitino problem and the moduli problem.

We reinterpret the Scherk-Schwarz (SS) boundary condition for SU(2)(R) in a compactified five-dimensional (5D) Poincare supergravity in terms of the twisted SU( 2) U gauge fixing in 5D conformal supergravity. In such translation, only the compensator hypermultiplet is relevant to the SS twist, and various properties of the SS mechanism can be easily understood. Especially, we show the correspondence between the SS twist and constant superpotentials within our framework.

We construct an effective N=1 superfield description of five-dimensional conformal supergravity. By the use of this description, we reinterpret some physical systems such as Scherk-Schwarz supersymmetry breaking from the conformal supergravity viewpoint. We also show how to introduce a radion fluctuation mode in this framework.

We clarify the radion superfield dependence of 5D N = 1 superspace action. The radion is treated as a dynamical field and appears in the action with the correct mode function. Our derivation is systematic and based on the superconformal formulation of 5D supergravity. We can read off the couplings of the dynamical radion superfield to the matter superfields from our result. The correct radion mass can be obtained by calculating the radion potential from our superspace action. © 2005 American Institute of Physics.

We derive 5D N = 1 superspace action including the radion superfield. The radion is treated as a dynamical field and identified as a solution of the equation of motion even in the presence of the radius stabilization mechanism. Our derivation is systematic and based on the superconformal formulation of 5D supergravity. We can read off the couplings of the dynamical radion superfield to the matter superfields from our result. The correct radion mass can be obtained by calculating the radion potential from our superspace action.

We discuss a gauged U(I)R supergravity on five-dimensional orbifold (S-1/Z(2)) in which a Z(2)-even U(1) gauge field takes part in the U(1)(R) gauging, and show the structure of Fayet-Iliopoulos (FI) terms allowed in such model. Some physical consequences of the FI terms are examined.

We discuss a gauged U(1)(R) supergravity on five-dimensional (5D) orbifold (S-1/Z(2)) in which both a Z(2)-even U(1) gauge field and the Z(2)-odd graviphoton take part in the U(1)(R) gauging. Based on the off-shell formulation of 5D supergravity, we analyze the structure of Fayet-Iliopoulos (FI) terms allowed in such model. Introducing a Z(2)-even U(1)(R) gauge field accompanies new bulk and boundary FI terms in addition to the known integrable boundary FI term which could be present in the absence of any gauged U(1)(R) symmetry. Some physical consequences of these new FI terms are examined.

We provide a systematic and practical method of deriving 5D supergravity action described by 4D superfields on a general warped geometry, including a non-BPS background. Our method is based on the superconformal formulation of 5D supergravity, but is easy to handle thanks to the superfield formalism. We identify the radion superfield in the language of 5D superconformal gravity, and clarify its appearance in the action. We also discuss SUSY breaking effects induced by a deformed geometry due to the backreaction of the radius stabilizer.

We discuss a locally supersymmetric formulation for the boundary FayetIliopoulos (FI) terms in 5-dimensional U(1) gauge theory on S-1/Z(2), using the four-form multiplier mechanism to introduce the necessary Z(2)-odd FI coefficient. Some physical consequences of the boundary FI terms, e.g., supersymmetry/gauge symmetry breakings and the generation of 5D kink mass for hypermultiplet, are studied within the full supergravity framework. For models giving a flat spacetime geometry, the only meaningful deformation of vacuum configuration induced by the FI terms is a kink-type vacuum expectation value of the vector multiplet scalar field. On the other hand, for models giving an warped geometry, the boundary FI terms can lead to more interesting vacuum deformation breaking gauge symmetry and/or N = 1 supersymmetry, and also provide a non-trivial connection between the orbifold radius and the hyperscalar dynamics on the boundaries which may be useful for the radion stabilization.

We discuss a locally supersymmetric formulation for the boundary FayetIliopoulos (FI) terms in 5-dimensional U(1) gauge theory on S-1/Z(2), using the four-form multiplier mechanism to introduce the necessary Z(2)-odd FI coefficient. Some physical consequences of the boundary FI terms, e.g., supersymmetry/gauge symmetry breakings and the generation of 5D kink mass for hypermultiplet, are studied within the full supergravity framework. For models giving a flat spacetime geometry, the only meaningful deformation of vacuum configuration induced by the FI terms is a kink-type vacuum expectation value of the vector multiplet scalar field. On the other hand, for models giving an warped geometry, the boundary FI terms can lead to more interesting vacuum deformation breaking gauge symmetry and/or N = 1 supersymmetry, and also provide a non-trivial connection between the orbifold radius and the hyperscalar dynamics on the boundaries which may be useful for the radion stabilization.

We examine the soft supersymmetry breaking parameters induced by the Scherk-Schwarz (SS) boundary condition in 5-dimensional orbifold field theory in which the quark and lepton zero modes are quasi-localized at the orbifold fixed points to generate the hierarchical Yukawa couplings. In such theories, the radion corresponds to a flavon to generate the flavor hierarchy and at the same time plays the role of the messenger of supersymmetry breaking. As a consequence, the resulting soft scalar masses and trilinear A-parameters of matter zero modes at the compactification scale are highly flavor-dependent, thereby can lead to dangerous flavor violations at low energy scales. We analyze in detail the low energy flavor violations in SS-dominated supersymmetry breaking scenario under the assumption that the compactification scale is close to the grand unification scale and the 4-dimensional effective theory below the compactification scale is given by the minimal supersymmetric standard model. Our analysis can be applied to any supersymmetry breaking mechanism giving a sizable F-component of the radion superfield, e.g. the hidden gaugino condensation model.

We systematically study VEVs of a gauge scalar field Sigma in a bulk U(1) vector multiplet and scalar fields in brane/bulk hypermultiplets charged under U(1) in the 5D S-1/Z(2) orbifold model with generic FI terms. A non-trivial VEV of Sigma generates bulk mass terms for U(1) charged fields, and their zero modes have non-trivial profiles. In particular, in the SUSY-breaking case, bosonic and fermionic zero modes have Gaussian profiles. Such non-trivial profiles are useful to explain hierarchical couplings. A toy model for SUSY breaking is studied, and it yields sizable D-term contributions to scalar masses. Because the overall magnitude of D-term contributions is the same everywhere in the bulk and also on both branes, we have to take into account these contributions and other SUSY-breaking terms to obtain a realistic description. We also give profiles and mass eigenvalues of higher modes.

We present four-dimensional gauge theories that describe physics on five-dimensional curved (warped) backgrounds, which includes bulk fields with various spins (vectors, spinors, and scalars). Field theory on the AdS(5) geometry is examined as a simple example of our formulation. Various properties of bulk fields on this background, e.g., the mass spectrum and field localization behavior, can be achieved within a fully four-dimensional framework. Moreover, that gives a localization mechanism for massless vector fields. We also consider supersymmetric cases, and show in particular that the conditions on bulk masses imposed by supersymmetry on warped backgrounds are derived from a four-dimensional supersymmetric theory on the flat background. As a phenomenological application, models are shown to generate hierarchical Yukawa couplings. Finally, we discuss possible underlying mechanisms which dynamically realize the required couplings to generate curved geometries.

The dynamically generated fermion mass is investigated in a flat brane world with (4+delta)-dimensional bulk space-time, and in the Randall-Sundrum (RS) brane world. We consider the bulk Yang-Mills theory interacting with a fermion confined on a four-dimensional brane. Based on the effective theory below a reduced cutoff scale on the brane, we formulate the Schwinger-Dyson equation of the brane fermion propagator. By using the improved ladder approximation we numerically solve the Schwinger-Dyson equation and find that the dynamical fermion mass is near the reduced cutoff scale on the brane for the flat brane world with deltagreater than or equal to3 and for the RS brane world. In the RS brane world Kaluza-Klein excited modes of the bulk gauge field localize around the y=piR brane and this enhances dynamical symmetry breaking on the brane. The decay constant of the fermion and the antifermion composite operator can be taken to be of the order of the electroweak scale, much smaller than the Planck scale. Therefore the electroweak mass scale can be realized from only the Planck scale in the RS brane world due to fermion and antifermion pair condensation. That is a dynamical realization of the Randall-Sundrum model which solves the weak-Planck hierarchy problem.

The chiral phase transition of strong-coupling Abelian gauge theories is investigated in brane world models. It is assumed that the gauge boson propagates in an extra dimension, i.e. we consider bulk gauge theories. The phase structure is analytically evaluated by using low-energy effective theories. We also numerically solve the ladder Schwinger-Dyson equation for the full fermion propagator including Kaluza-Klein (KK) excitation modes of the gauge field. It is found that the chiral phase transition is of second order, and the critical value of the coupling constant is obtained. The extra dimension has a large influence on the chiral phase transition. It is studied how the number of KK modes affects the chiral phase transition.

The dynamical fermion mass generation in the four-dimensional brane is discussed in a model with five-dimensional Kaluza-Klein fermions in interaction with four-dimensional fermions. It is found that the dynamical fermion masses are generated beyond the critical radius of the compactified extra dimensional space and may be made small compared with the masses of the Kaluza-Klein modes.

The path-integral method of calculating the Casimir energy between two parallel conducting plates is developed within the framework of supersymmetric quantum electrodynamics at vanishing temperature as well as at finite temperature. The choice of the suitable boundary condition for the photino on the plates is argued and the physically acceptable condition is adopted which eventually breaks the supersymmetry. The photino mass term is introduced in the Lagrangian and the photino mass dependence of the Casimir energy and pressure is fully investigated.