Flat Higgs potential from Planck scale supersymmetry breaking

The observed Higgs boson mass poses a new puzzle in addition to the longstanding problem of the origin of the electroweak scale; the shallowness of the Higgs potential. The Higgs quartic coupling even seems to vanish at around the Planck scale within the uncertainties of the top quark mass and the strong gauge coupling. We show that the shallowness of the Higgs potential might be an outcome of supersymmetry breaking at around the Planck scale. There, the electroweak fine-tuning in the Higgs quadratic terms leads to an almost vanishing quartic coupling at around the Planck scale

Lower bound of the tensor-to-scalar ratio r≳0.1 in a nearly quadratic chaotic inflation model in supergravity

We consider an initial condition problem in a nearly quadratic chaotic inflation model in supergravity. We introduce shift symmetry breaking not only in the superpotential but also in the Kahler potential. In this model the inflaton potential is nearly quadratic for inflaton field values around the Planck scale, but deviates from the quadratic one for larger field values. As a result, the prediction on the tensor-to-scalar ratio can be smaller than that of a purely quadratic model. Due to the shift symmetry breaking in the Kahler potential, the inflaton potential becomes steep for large inflaton field values, which may prevent inflation from naturally taking place in a closed universe. We estimate an upper bound on the magnitude of the shift symmetry breaking so that inflation takes place before a closed universe with a Planck length size collapses, which yields a lower bound on the tensor-to-scalar ratio, r≳0.1

Wino dark matter and future dSph observations

We discuss the indirect detection of the wino dark matter utilizing gammaray observations of dwarf spheroidal galaxies (dSphs). After carefully reviewing current limits with particular attention to astrophysical uncertainties, we show prospects of the wino mass limit in future gamma-ray observation by the Fermi-LAT and the GAMMA-400 telescopes. We find that the improvement of the so-called J -factor of both the classical and the ultra-faint dSphs will play a crucial role to cover whole mass range of the wino dark matter. For example, with δ (log 10 J ) = 0 . 1 for both the classical and the ultra-faint dSphs, whole wino dark matter mass range can be covered by 15 years and 10 years data at the Fermi-LAT and GAMMA-400 telescopes, respectively

Upper bounds on gluino, squark and higgisino masses in the focus point gaugino mediation with a mild fine tuning Δ ≤ 100

We show that upper bounds on the masses for gluino, squarks and higgsino are m gluino ≤5 . 5 TeV , m squark ≤ 4 . 7 TeV and m higgsino ≤ 650 GeV in a focus point gaugino mediation. Here, we impose a mild fine tuning Δ ≤ 100. This result shows that it is very challenging for the LHC to exclude the focus point gaugino mediation with the mild fine tuning. However, the ILC may have a potential for excluding the focus point gaugino mediation with such a mild fine tuning. It is also shown that vector-like matters reduce the required masses of the squark (stop) and gluino to explain the observed Higgs boson mass and enhance the testability of the model at the LHC. The fine-tuning is still kept mild

Decay rates of Gaussian-type I-balls and Bose-enhancement effects in 3+1 dimensions

I-balls/oscillons are long-lived spatially localized lumps of a scalar field which may be formed after inflation. In the scalar field theory with monomial potential nearly and shallower than quadratic, which is motivated by chaotic inflationary models and supersymmetric theories, the scalar field configuration of I-balls is approximately Gaussian. If the I-ball interacts with another scalar field, the I-ball eventually decays into radiation. Recently, it was pointed out that the decay rate of I-balls increases exponentially by the effects of Bose enhancement under some conditions and a non-perturbative method to compute the exponential growth rate has been derived. In this paper, we apply the method to the Gaussian-type I-ball in 3+1 dimensions assuming spherical symmetry, and calculate the partial decay rates into partial waves, labelled by the angular momentum of daughter particles. We reveal the conditions that the I-ball decays exponentially, which are found to depend on the mass and angular momentum of daughter particles and also be affected by the quantum uncertainty in the momentum of daughter particles

Dynamical chaotic inflation in the light of BICEP2

The measurement of a large tensor-to-scalar ratio by the BICEP2 experiment, <math altimg="si1.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mi>r</mi><mo>=</mo><msubsup><mrow><mn>0.20</mn></mrow><mrow><mo>−</mo><mn>0.05</mn></mrow><mrow><mo>+</mo><mn>0.07</mn></mrow></msubsup></math> , severely restricts the landscape of viable inflationary models and shifts attention once more towards models featuring large inflaton field values. In this context, chaotic inflation based on a fractional power-law potential that is dynamically generated by the dynamics of a strongly coupled supersymmetric gauge theory appears to be particularly attractive. We revisit this class of inflation models and find that, in the light of the BICEP2 measurement, models with a non-minimal gauge group behind the dynamical model seem to be disfavored, while the model with the simplest group, i.e. <math altimg="si2.gif" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi mathvariant="italic">SU</mi></mrow><mo stretchy="false">(</mo><mn>2</mn><mo stretchy="false">)</mo></math> , is consistent with all results. We also discuss how the dynamical model can be distinguished from the standard chaotic inflation model based on a quadratic inflaton potential

CP-safe gravity mediation and muon g 2

We propose a CP-safe minimal supersymmetric (SUSY) standard model in gravity mediation, where the phases of the Higgs parameter, scalar trilinear couplings, and gaugino mass parameters are all aligned. Since all dangerous CP-violating phases are suppressed, we are now safe to consider low-energy SUSY scenarios under the assumption that the SUSY flavor-changing neutral current problem is solved. As an application, we consider a gravity mediation model explaining the observed muon anomaly. The CP-safe property originates in two simple assumptions: SUSY breaking in the Kähler potential and the shift symmetry of a SUSY-breaking field . As a result of the shift symmetry, the imaginary part of behaves as a QCD (quantum chromodynamics) axion, leading to an intriguing possibility: the strong CP problem in QCD and the SUSY CP problem are solved simultaneously

Phase locked inflation. Effectively trans-Planckian natural inflation

A model of natural inflation with an effectively trans-Planckian decay constant can be easily achieved by the “phase locking” mechanism while keeping field values in the effective field theory within the Planck scale. We give detailed description of “phase locked” inflation based on this mechanism. We also construct supersymmetric natural inflation based on this mechanism and show that the model is consistent with low scale supersymmetry. We also investigate couplings of the inflaton with the minimal supersymmetric standard model to achieve an appropriate reheating process. Interestingly, in a certain class of models, we find that the inflation scale is related to the mass of the right-handed neutrino in a consistent way with the seesaw mechanism

R -symmetric axion/natural inflation in supergravity via deformed moduli dynamics

We construct a natural inflation model in supergravity where the inflaton is identified with a modulus field possessing a shift symmetry. The superpotential for the inflaton is generated by meson condensation due to strong dynamics with deformed moduli constraints. In contrast to models based on gaugino condensation, the inflaton potential is generated without R -symmetry breaking and hence does not depend on the gravitino mass. Thus, our model is compatible with low scale supersymmetry

Cosmologically safe QCD axion as a present from extra dimension

We propose a QCD axion model where the origin of PQ symmetry and suppression of axion isocurvature perturbations are explained by introducing an extra dimension. Each extra quark–antiquark pair lives on branes separately to suppress PQ breaking operators. The size of the extra dimension changes after inflation due to an interaction between inflaton and a bulk scalar field, which implies that the PQ symmetry can be drastically broken during inflation to suppress undesirable axion isocurvature fluctuations