On the Solution to the Polonyi Problem with No-Scale Type Supergravity

We study the solution to the Polonyi problem in the framework of no-scale type supergravity. In such a model, Polonyi field can weigh as $O(10{\rm TeV})$ and decay just before the big-bang nucleosynthesis. It is shown that in spite of a large entropy production by the decay of the Polonyi field, one can naturally explain the present value of the baryon-to-entropy ratio, $n_B/s \sim (10^{-10}-10^{-11})$ if the Affleck-Dine mechanism for baryogenesis works. It is pointed out, however, that there is another cosmological problem related to the abundance of the lightest superparticles produced by the decay of the Polonyi field.Comment: Talk given at the Yukawa International Seminar '95 in Kyoto, 21 - 26 August, 199

A Solution to the Polonyi Problem in the Minimum SUSY-GUT

We show that the Polonyi problem is solved in the minimum SUSY-GUT model in which a self-coupling strength for a heavy Higgs $\Sigma$, $\lambda\Sigma^{3}$, is very small $\lambda\sim 10^{-6}$. It is stressed that with this small $\lambda$ the mass of the physical $\Sigma$ becomes m_{\Sigma} \sim 10^{12}\GEV and the unification scale is raised up to the gravitational one, M\simeq 2\times 10^{18}\GEV. A potential problem, however, is also pointed out in this GUT model

Electromagnetic Cascade in the Early Universe and its Application to the Big-Bang Nucleosynthesis

We investigate the electromagnetic cascade initiated by injection of very high energy photons in the early Universe and calculate the cascade spectrum by solving a set of Boltzmann equations numerically. In the calculation we take account of Compton scattering off the background electrons and pair creation off the background nucleons as well as photon-photon processes and inverse Compton scattering. We also apply our cascade spectrum to the big bang nucleosynthesis with photo-dissociation processes due to heavy unstable particles and obtain the constraint on their lifetime and abundance.Comment: 21pages (compressed and uuencoded postscript file including 6 figures

Gravitino Production in the Inflationary Universe and the Effects on Big-Bang Nucleosynthesis

Gravitino production and decay in the inflationary universe are reexamined. Assuming that the gravitino mainly decays into a photon and a photino, we calculate the upperbound on the reheating temperature. Compared to previous works, we have essentially improved the following two points: (i) the helicity $\pm\frac{3}{2}$ gravitino production cross sections are calculated by using the full relevant terms in the supergravity lagrangian, and (ii) the high energy photon spectrum is obtained by solving the Boltzmann equations numerically. Photo-dissociation of the light elements (D, T, $^3$He, $^4$He) leads to the most stringent upperbound on the reheating temperature, which is given by ($10^{6}$--$10^{9}$)GeV for the gravitino mass 100GeV--1TeV. On the other hand, requiring that the present mass density of photino should be smaller than the critical density, we find that the reheating temperature have to be smaller than ($10^{11}$--$10^{12}$)GeV for the photino mass (10--100)GeV, irrespectively of the gravitino mass. The effect of other decay channels is also considered

Limit on the Color-Triplet Higgs Mass in the Minimum Supersymmetric SU(5) Model

In the minimum supersymmetric SU(5) GUT, we derive the upper limit on the mass of the color-triplet Higgs multiplets as \mhc\leq 2.4\times 10^{16}~\GEV (90 \% C.L.) taking all possible corrections into account in a renormalization group analysis. If the above upper limit is compared with a limit on \mhc from the negative search for the proton decay; \mhc \geq 2.0\times 10^{16}~\GEV (in which effects of the larger top-quark mass are included), the minimum supersymmetric SU(5) GUT is severely constrained

Upper Bound on the Gluino Mass in Supersymmetric Models with Extra Matters

We discuss the upper bound on the gluino mass in supersymmetric models with vector-like extra matters. In order to realize the observed Higgs mass of 125 GeV, the gluino mass is bounded from above in supersymmetric models. With the existence of the vector-like extra matters at around TeV, we show that such an upper bound on the gluino mass is significantly reduced compared to the case of minimal supersymmetric standard model. This is due to the fact that radiatively generated stop masses as well the stop trilinear coupling are enhanced in the presence of the vector-like multiplets. In a wide range of parameter space of the model with extra matters, the gluino is required to be lighter than $\sim 3$ TeV, which is likely to be within the reach of forthcoming LHC experiment.Comment: 16 pages, 6 figures; references adde

Lepton Flavor Violations in High-Scale SUSY with Right-Handed Neutrinos

Motivated by the recent discovery of the Higgs boson at m_h = 126 GeV and also by the non-observation of superparticles at the LHC, high-scale SUSY, where the superparticles are as heavy as O(10) TeV, has been recently proposed. We study lepton-flavor violations (LFVs) in the high-scale SUSY with right-handed neutrinos. Even if the slepton masses are of O(10) TeV, the renormalization group (RG) effects on the slepton mass-squared matrix may induce large enough LFVs which are within the reach of future LFV experiments. We also discuss the implication of the right-handed neutrinos on the electroweak symmetry breaking in such a model, and show that the parameter region with the successful electroweak symmetry breaking is enlarged by the RG effects due to the right-handed neutrinos.Comment: 11 pages, 3 figure

The muon anomalous magnetic dipole moment in the minimal supersymmetric standard model

The muon anomalous magnetic dipole moment (MDM) is calculated in the framework of the minimal supersymmetric standard model (MSSM). In this paper, we discuss how the muon MDM depends on the parameters in MSSM in detail. We show that the contribution of the superparticle-loop becomes significant especially when \tan\beta is large. Numerically, it becomes O(10^{-8}-10^{-9}) in a wide parameter space, which is within the reach of the new Brookhaven E821 experiment

Naturalness Re-examined: Implications for Supersymmetry Searches

We discuss the origin of "focus points" in the scalar mass RGEs of the MSSM and their implications for collider searches. We present a new exact analytic solution to the homogeneous system of scalar mass RGEs in the MSSM for general $\tan\beta$. This is then used to prove that the focus point for $m^2_{H_u}$ depends only on the value of the top Yukawa coupling at the {\em weak} scale (not its value at the GUT scale) and is independent of the bottom Yukawa coupling.Comment: 7 pages, 2 figures, to appear in the Proceedings of PASCOS'99, Lake Tahoe, December 10-16, 199