54193494
Sparticle spectrum of large volume compactification
We examine the large volume compactification of Type IIB string theory or its F theory limit and the associated supersymmetry breakdown and soft terms. It is crucial to incorporate the loop-induced moduli mixing, originating from radiative corrections to the Kähler potential. We show that in the presence of moduli mixing, soft scalar masses generically receive a D-term contribution of the order of the gravitino mass m3/2 when the visible sector cycle is stabilized by the D-term potential of an anomalous U(1) gauge symmetry, while the moduli-mediated gaugino masses and A-parameters tend to be of the order of m3/2/8π2. It is noticed also that a too large moduli mixing can destabilize the large volume solution by making it a saddle point.
119256844
Effective interactions of axion supermultiplet and thermal production of axino dark matter
We discuss the effective interactions of axion supermultiplet, which might be important for analyzing the cosmological aspect of supersymmetric axion model. Related to axino cosmology, it is stressed that three seemingly similar but basically different quantities, the Wilsonian axino-gluino-gluon coupling, the 1PI axino-gluino-gluon amplitude, and the PQ anomaly coefficient, should be carefully distinguished from each other for correct analysis of the thermal production of axinos in the early Universe. It is then noticed that the 1PI axino-gluino-gluon amplitude at energy scale p in the range MΦ < p < vPQ is suppressed by MΦ2/p2 in addition to the well-known suppression by p/16π2vPQ, where MΦ is the mass of the heaviest PQ-charged and gauge-charged matter supermultiplet in the model, which can be well below the PQ scale vPQ. As a result, axino production at temperature T > MΦ is dominated by the production by matter supermultiplet, not by the production by gauge supermultiplet. Still the axino production rate is greatly reduced if MΦ ≪ vPQ, which would make the subsequent cosmology significantly altered. This would be most notable in the supersymmetric DFSZ model in which MΦ corresponds to the Higgsino mass which is around the weak scale, however a similar reduction is possible in the KSVZ model also. We evaluate the relic axino density for both the DFSZ and KSVZ models while including the axino production in the processes involving the heaviest PQ-charged and gauge-charged matter supermultiplet.
53338971
Mixed mediation of supersymmetry breaking with anomalous U(1) gauge symmetry
Models with anomalous U(1) gauge symmetry contain various superfields which can have nonzero supersymmetry breaking auxiliary components providing the origin of soft terms in the visible sector, e.g. the U(1) vector superfield, the modulus or dilaton superfield implementing the Green-Schwarz anomaly cancellation mechanism, U(1)-charged but standard model singlet matter superfield required to cancel the Fayet-Iliopoulos term, and finally the supergravity multiplet. We examine the relative strength between these supersymmetry breaking components in a simple class of models, and find that various different mixed mediations of supersymmetry breaking, involving the modulus, gauge, anomaly and D-term mediations, can be realized depending upon the characteristics of D-flat directions and how those D-flat directions are stabilized with a vanishing cosmological constant. We identify two parameters which represent such properties and thus characterize how the various mediations are mixed. We also discuss the moduli stabilization and soft terms in a variant of KKLT scenario, in which the visible sector Kähler modulus is stabilized by the D-term potential of anomalous U(1) gauge symmetry.
4991507
Higgs phenomenology in the Peccei-Quinn invariant NMSSM
A bstractWe study the Higgs phenomenology in the Peccei-Quinn invariant NMSSM (PQ-NMSSM) where the low energy mass parameters of the singlet superfield are induced by a spontaneous breakdown of the Peccei-Quinn symmetry. In the generic NMSSM, scalar mixing among CP-even Higgs bosons is constrained by the observed properties of the SM-like Higgs boson, as well as by the LEP bound on the chargino mass and the perturbativity bound on the singlet Yukawa coupling. In the minimal PQ-NMSSM, scalar mixing is further constrained due to the presence of a light singlino-like neutralino. It is noticed that the 2σ excess of the LEP $ Zb\overline{b} $ events at $ {m_{{b\overline{b}}}} $ ≃ 98 GeV can be explained by a singlet-like 98 GeV Higgs boson in the minimal PQ-NMSSM with low tan β, stops around or below 1 TeV, and light doublet-higgsinos around the weak scale.
119238385
THERMAL PRODUCTION OF AXINO DARK MATTER
We discuss certain features of the low energy effective interactions of axion supermultiplet, which are relevant for axino cosmology, and examine the implication to thermal production of axino in the early Universe.
53991379
Higgs mixing and diphoton rate enhancement in NMSSM models
A bstractWe study the implications of the LHC Higgs signals on the Higgs mixing in the next-to-minimal supersymmetric standard model (NMSSM). The Higgs couplings can depart from their values in the standard model (SM) due to mixing effects. However the Higgs signal rate in the WW and ZZ channels can remain close to the SM values, as observed at the LHC, even if the SM-like Higgs boson with a mass near 125 GeV has a large singlet component. This allows to get a sizable enhancement in the Higgs to diphoton rate through the charged-higgsino loop contribution, as well as a sizable reduction of the Higgs to $ b\overline{b} $ and ττ rates through the mixing effects, with little deviation in the WW and ZZ signal rates from the SM prediction. We find that an enhancement of diphoton signals by a factor of 1.5 or more, and also a reduction of $ b\overline{b} $ and ττ signals by a factor of 0.5, can be obtained in the region of parameter space consistent with the constraints on the higgsino mass parameter and the singlet coupling to the Higgs doublets, which determine the Higgs mixing.
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.
15721073
Gauge unification via stable brane recombination
We study the transition between parallel and intersecting branes on a torus. Spontaneous symmetry breaking of nonabelian gauge symmetry is understood as brane separation, and a more general intermediate deformation is discussed. We argue that there exists supersymmetry preserving transition and we can always have parallel branes as a final state. The transition is interpreted due to dynamics of the F- and D-string junctions and their generalization to (F, Dp) bound states. The gauge group and coupling unification is achieved, also as a result of supersymmetry. From the tadpole cancelation condition, we naturally have intersecting brane models as broken phases of type-I theory with SO(32) gauge group.
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.
55020130
Weak Mixing Angle and Proton Stability in F-theory GUT
Abstract It is pointed out that a class of flipped SU ( 5 ) models based on F-theory naturally explains the gauge coupling unification. It is because the gauge group SU ( 5 ) × U ( 1 ) X is embedded in SO ( 10 ) and E 8 . To prohibit the dimension 4 and 5 proton decay processes, the structure group associated with monodromy should be SU ( 3 ) ⊥ or smaller. Extra heavy vector-like pairs of { 5 − 2 , 5 ¯ 2 } except only one pair of Higgs should be disallowed, because they could induce the unwanted dimension 5 proton decays. We construct a simple global F-theory model considering these points. To maintain sin 2 θ W 0 = 3 8 at the GUT scale, the fluxes are turned on only on the flavor branes.
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.