5542247
Three family Z3 orbifold trinification, MSSM and doublet–triplet splitting problem
Abstract A Z 3 orbifold compactification of E 8 × E 8 ′ heterotic string is considered toward a trinification SU (3) 3 with three light families. The GUT scale VEVs of the SU (2) W × U (1) Y × SU (3) c singlet chiral fields in two sets of the trinification spectrum allow an acceptable symmetry breaking pattern toward MSSM. We show that a doublet–triplet splitting is related to the absence of a Δ B nonzero operator.
16283086
Three generation magnetized orbifold models
Abstract 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.
118237829
UV Completion of Axion
A multiple number of global U(1)s, arising from accidental symmetries up to a certain order of the potential, enjoy lowering the axion decay constant from UV‐scale and evading supersymmetric Fayet–Illiopoulos term constraints.
119201914
Extended gauge symmetries in F-theory
We study gauge symmetry in F-theory in light of global aspects. For this, we consider not only a simple (local) group, but also a semi-simple group with Abelian factors. Once we specify the complete gauge group by decomposing the discriminant, analogous to arranging 7-branes, we can derive the matter contents, their localization and the relation to enhanced groups. Global constraints coming from Calabi-Yau conditions and anomaly cancellations imply a unified group. The semisiple group shows explicit formation of matter curves and nontriviality of its embedding into exceptional group. Also the dual heterotic string vacua with line bundles provide a guide on the unification.
119243457
Non-Abelian Discrete Flavor Symmetries on Orbifolds
We study non-Abelian flavor symmetries on orbifolds, S1/Z2 and T2/Z3. Our extra dimensional models realize DN, Σ(2N2), Δ(3N2) and Δ(6N2) including A4 and S4. In addition, one can also realize their subgroups such as QN, T7, etc. The S3 flavor symmetry can be realized on both S1/Z2 and T2/Z3 orbifolds.
118042770
SU(3) x SU(2) x U(1) Vacua in F-Theory
The Standard Model group and matter spectrum is obtained in vacua of F-theory, without resorting to an intermediate unification group. The group SU(3) x SU(2) x U(1)_Y is the commutant to SU(5)_t \times U(1)_Y structure group of a Higgs bundle in E_8 and is geometrically realized as a deformation of I_5 singularity. Lying along the unification groups of E_n, our vacua naturally inherit their unification structure. By modding SU(5)_t out by Z_4 monodromy group, we can distinguish Higgses from lepton doublets by matter parity. Turning on universal G-flux on this part, the spectrum contains three generations of quarks and leptons, as well as vectorlike pairs of electroweak and colored Higgses. Minimal Yukawa couplings is obtained at the renormalizable level.
118886098
Dark radiation and small-scale structure problems with decaying particles
Although the standardCDM model describes the cosmic microwave background radiation and the large scale structure of the Universe with great success, it has some tensions with observations in the effective number of neutrino species (dark radiation) and the number of small scale structures (overabundance problem). Here we propose a scenario which can relax these tensions by producing both dark matter and dark radiation by late decays of heavy particle. Thanks to the generation mechanism, dark matters are rather warm so that the small-scale structure problem is resolved. This scenario can be naturally realized in supersymmetric axion model, in which axions produced by saxion decays provide dark radiation, while axinos from saxion decays form warm dark matter. We identify a parameter region of supersymmetric axion model satisfying all known cosmological constraints.
119366917
Double suppression of FCNCs in supersymmetric models
A mechanism for double suppression of flavor-changing neutral currents (FCNCs) and CP violating phases in supersymmetric models is suggested. At M{sub SUSY} they are suppressed due to a nonabelian discrete flavor symmetry, and the infrared attractive force of gauge interactions in extra dimensions are used to suppress them at the compactification scale. We present a concrete model, which is a simple extension of S{sub 3} invariant minimal supersymmetric standard model, where only SU(2){sub L} and SU(3){sub C} gauge multiplets are assumed to propagate in the bulk. We find that a disorder of 2 orders of magnitude in soft supersymmetry breaking parameters above the compactification scale may be allowed to satisfy experimental constraints on FCNC processes and CP violating phenomena.
118336374
Techni-dilaton as dark matter
Abstract We propose a new dark matter candidate, light decoupled techni-dilaton , which arises from the almost scale-invariant/conformal (extreme walking) technicolor. We investigate its characteristic nature and discuss several cosmological and astrophysical constraints. It turns out that techni-dilatons are extremely weakly interacting and produced dominantly by the non-thermal mechanism to become the main component of dark matter with mass range between around 0.01 eV and 500 eV for extreme walking technicolor scenarios.
14862395
Softness of brane-localized supersymmetry breaking on orbifolds
Abstract We consider the brane-localized supersymmetry breaking in 5D compactified on S 1 / Z 2 . In case of a bulk gaugino with arbitrary brane masses for its even and odd modes, we find the mass spectrum and the wave functions of gaugino. We show that the gaugino masses at the distant brane are soft in the usual sense in the effective field theory with zero modes of bulk gauge fields and they are also extremely soft in view of the one-loop finite mass of a brane scalar in the KK regularization.
16830627
U(1)R-mediated supersymmetry breaking from a six-dimensional flux compactification
We study the U(1)R-mediated supersymmetry breaking in a flux compactification of 6D chiral gauged supergravity with codimension-two branes. We consider a concrete model with manifest U(1)R invariance for moduli stabilization and visible sector in the context of 4D effective supergravity with gauged U(1)R and determine soft scalar masses in the visible sector mainly by a nonzero U(1)R D-term. We obtain a low energy superparticle spectrum and discuss on the implications of the obtained non-universal scalar soft masses on the SUSY phenomenology such as dark matter relic abundances.