101 research outputs found

    SUSY CP Problem in Gauge Mediation Model

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    SUSY CP problem in the gauge mediation supersymmetry breaking model is reconsidered. We pay particular attention to two sources of CP violating phases whose effects were not seriously studied before; one is the effect of the breaking of the GUT relation among the gaugino masses due to the field esponsible for the GUT symmetry breaking, and the other is the supergravity effect on the supersymmetry breaking parameters, in particular, on the bi-linear supersymmetry breaking Higgs mass term. We show that both of them can induce too large electric dipole moments of electron, neutron, and so on, to be consistent with the experimental bounds.Comment: 15 pages, 3 figures, corrected typos, The version to appear in PL

    Light Higgsino and Gluino in RR-invariant Direct Gauge Mediation

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    We provide a simple solution to the μ\mu-BμB_\mu problem in the "RR-invariant direct gauge mediation model". With the solution, the Higgsino and gluino are predicted to be light as O(100)\mathcal{O}(100)GeV and O(1)\mathcal{O}(1)TeV, respectively. Those gluino and Higgsino can be accessible at the LHC and future collider experiments. Moreover, dangerous dimension five operators inducing rapid proton decays are naturally suppressed by the RR-symmetry.Comment: 14 pages, 3 figure

    Upper Bounds on Gluino, Squark and Higgisino Masses in the Focus Point Gaugino Mediation with a Mild Fine Tuning Δ≤100\Delta \le 100

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    We show that upper bounds on the masses for gluino, squarks and higgsino are mgluino≤5.5m_{gluino} \le 5.5 TeV, msquark≤4.7m_{squark} \le 4.7 TeV and mhiggsino≤650m_{higgsino} \le 650 GeV in a focus point gaugino mediation. Here, we impose a mild fine tuning Δ≤100\Delta \le 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.Comment: 13 pages, 2 figure

    Focus Point in Gaugino Mediation ~ Reconsideration of the Fine-tuning Problem ~

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    We reconsider the fine-tuning problem in SUSY models, motivated by the recent observation of the relatively heavy Higgs boson and non-observation of the SUSY particles at the LHC. Based on this thought, we demonstrate a focus point-like behavior in a gaugino mediation model, and show that the fine-tuning is indeed reduced to about 2 percent level if the ratio of the gluino mass to wino mass is about 0.4 at the GUT scale. We show that such a mass ratio may arise naturally in a product group unification model without the doublet-triplet splitting problem. This fact suggests that the fine-tuning problem crucially depends on the physics at the high energy scale.Comment: 13 pages, 4 figures; published versio

    Effects of Large Threshold Corrections in Supersymmetric Type-I Seesaw Model

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    We investigate lepton flavor violating (LFV) radiative processes and the relic abundance of neutralino dark matter in supersymmetric type-I seesaw model. We carefully derive threshold corrections to the flavor off-diagonal elements of slepton mass matrix and up-type Higgs mass squared and find that they can be large in the case of large BN0B_N^0. We examine how the branching ratios of LFV radiative decays and the relic abundance of neutralino dark matter can be significantly affected by the large threshold corrections. Soft scalar mass squared parameter of up-type Higgs scalar is also affected by the threshold corrections. Since the higgsino mass depends on the mass parameter for up-type Higgs, the LFV processes and the relic abundance of the neutralino dark matter are correlated with each other. We show that there are parameter regions where the predictions of the relic abundance of neutralino dark matter are consistent with WMAP observation and the branching ratios of LFV radiative decays are predicted to be testable in future experiments. We find that the masses of scalar supersymmetric particles are not necessarily small so that the branching ratios of LFV decays can be testable in future experiment, which is distinctive feature of this scenario.Comment: 32 pages, 6 figures, references are added, the version to appear in JHE
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