119158878
Inflation in supergravity without Kähler potential
We propose a new class of inflation models in supergravity with higher derivative terms. In those models, the K\"ahler potential does not contain the inflaton multiplet, but a supersymmetric derivative term does. In the models, inflation is effectively driven by a single scalar field with a standard kinetic term and a scalar potential. Remarkably, the so-called $\eta$ problem does not exist in our models.
119278125
SUSY flavor structure of generic 5D supergravity models
We perform a comprehensive and systematic analysis of the SUSY flavor structure of generic 5D supergravity models on S1/Z2 with multiple Z2-odd vector multiplets that generate multiple moduli. The SUSY flavor problem can be avoided due to contact terms in the 4D effective Kähler potential peculiar to the multi-moduli case. A detailed phenomenological analysis is provided based on an illustrative model.
44450900
Illustrating SUSY breaking effects on various inflation mechanisms
A bstractWe consider the supersymmetry breaking effects on typical inflation models with different types of Kähler 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.
119288533
Reheating processes after Starobinsky inflation in old-minimal supergravity
A bstractWe study reheating processes and its cosmological consequences in the Starobinsky model embedded in the old-minimal supergravity. First, we consider minimal coupling between the gravity and matter sectors in the higher curvature theory, and transform it to the equivalent standard supergravity coupled to additional matter superfields. We then discuss characteristic decay modes of the inflaton and the reheating temperature TR. Considering a simple model of supersymmetry breaking sector, we estimate gravitino abundance from inflaton decay, and obtain limits on the masses of gravitino and supersymmetry breaking field. We find TR ≃ 1.0 × 109 GeV and the allowed range of gravitino mass as 104 GeV ≲ m3/2 ≲ 105 GeV, assuming anomaly-induced decay into the gauge sector as the dominant decay channel.
2763498
One-loop corrections to the chargino and neutralino mass matrices in the on-shell scheme
We present a consistent procedure for the calculation of the one-loop corrections to the charginos and neutralinos by using their on-shell mass matrices. The on-shell gaugino mass parameters M and M', and the Higgsino mass parameter \mu are defined by the elements of these on-shell mass matrices. The on-shell mass matrices are different by finite one-loop corrections from the tree-level ones given in terms of the on-shell parameters. When the on-shell M and \mu are determined by the chargino sector, the neutralino masses receive corrections up to 4%. This must be taken into account in precision measurements at future e^+ e^- linear colliders.
119423425
Large tan beta SUSY QCD corrections to B -> X_s gamma
The charged-Higgs boson contributions to the Wilson coefficients C_7 and C_8, relevant for the decay B -> X_s gamma, are discussed in supersymmetric models at large tan beta. These contributions receive two-loop O(alpha_s tan beta) corrections by squark-gluino subloops, which are possibly large and nondecoupling in the limit of heavy superpartners. In previous studies, the relevant two-loop Feynman integrals were approximated by using an effective two-Higgs-doublet lagrangian. However, this approximation is theoretically justified only when the typical supersymmetric scale M_SUSY is sufficiently larger than the electroweak scale m_weak \sim (m_W,m_t) and the mass of the charged-Higgs boson m_{H^\pm}. Here we evaluate these two-loop integrals exactly and compare the results with the existing, approximated ones. We then examine the validity of this approximation beyond the region where it has been derived, i.e. for m_H \gtap M_SUSY and/or M_SUSY \sim m_weak.
1388004
Low-scale anomalous U(1) and decoupling solution to supersymmetric flavor problem
Abstract Supersymmetric standard models where the ultraviolet cut-off scale is only a few orders of magnitude higher than the electroweak scale are considered. Phenomenological consequences of this class of models are expected to be very different from, for example, the conventional supergravity scenario. We apply this idea to a model with an anomalous U(1) gauge group and construct a viable model in which some difficulties of the decoupling solution to the supersymmetric flavor problem are ameliorated.
16196762
Electroweak Precision Measurements and the Minimal Supersymmetric Standard Model
We discuss supersymmetric contributions to the electroweak precision measurements in the Minimal Supersymmetric Standard Model for two cases: the quark-lepton universality violation $\delta_{q\ell}$ in charged currents and the ratio $R_b=\Gamma(Z\rightarrow b\bar{b})/\Gamma(Z\rightarrow \rm hadrons)$. The recent experimental data suggest deviations from the Standard Model for these observables, at the 1-$\sigma$ level for the former and at more than 3-$\sigma$ level for the latter. We analyze the non-oblique corrections from the SUSY particles to explain these discrepancies. The observed non-zero $\delta_{q\ell}$ may be explained by relatively light sleptons, charginos and neutralinos. Although the observed excess of $R_b$ can be explained by very light scalar top and chargino for low $\tan\beta$, this interpretation is severely constrained by the opening of exotic decay modes for the top quark.
17333378
SUSY - QCD corrections to top and bottom squark decays into Higgs bosons
We calculate the $\mathcal{O}({\ensuremath{\alpha}}_{s})$ SUSY-QCD corrections to the widths of top and bottom squark decays into Higgs bosons within the minimal supersymmetric standard model. We give the complete analytical formulas, paying particular attention to the on-shell renormalization of the soft SUSY-breaking parameters. We also perform a detailed numerical analysis of both top and bottom squark decays into all Higgs bosons ${h}^{0},$ ${H}^{0},$ ${A}^{0},$ and ${H}^{\ifmmode\pm\else\textpm\fi{}}.$ We find that the SUSY-QCD corrections are significant, mostly negative, and of the order of a few ten percent.