arXiv subjects

Motoi Endo

Publications and source records attributed to Motoi Endo.

98 records · Page 6Linked to original sources

arXiv2004

Radiative CP Phases in Supergravity Theories

In this letter, we point out that possible sources of CP violation originate from radiative corrections to soft terms which are ubiquitous in supergravity theories and also in other high-energy frameworks of supersymmetry breaking. With these radiative phases of gaugino masses and scalar couplings, a complex phase of Higgs holomorphic mass parameter is generated via renormalization-group running down to low energy. It is found that its phase value is mainly controlled by wino as well as gluino, which generally receive different radiative corrections to their complex phases, even if the leading part of mass parameters follow from the universality hypothesis. The radiatively generated phases are constrained by the existing experimental bounds on electric dipole moments, and may be detectable in future measurements. They are also found to be available for the cancellation mechanism to be worked.

hep-ph↗

arXiv2003

New Constraint on Squark Flavor Mixing from 199Hg Electric Dipole Moment

A new constraint is obtained on the CP-violating flavor mixing between the left-handed top scalar quark (\tilde{t}_L) and charm scalar quark (\tilde{c}_L), by considering a chargino loop contribution to chromo-electric dipole moment of strange quark, which is limited by the electric dipole moment of the ^{199}Hg atom. It is found that the flavor mixing should be suppressed to the level of {\cal O}(0.1) for the CP phase of order unity, when \tan βis relatively large and sparticle masses lie in a few hundred GeV range. Although it is much stronger than the known constraint from the chargino loop contribution to b \to s γ, the moderate constraint we obtain here is argued to leave room for sizable supersymmetric contribution to the CP asymmetry in B_d^0 \to ϕK_s.

hep-ph↗

arXiv2003

CP violation in models with TeV-scale SUSY breaking

We estimate contributions of the goldstino supermultiplet to the electric dipole moment (EDM) in the case that the SUSY breaking scale Λ_S is of order the TeV scale. We found that such contributions can saturate the experimental bound if Λ_S is close to the soft mass scale. We also discuss EDM in the gaugino mediated scenario on the warped geometry as an example of models with the TeV-scale SUSY breaking.

hep-ph↗

arXiv2003

Raising Sfermion Masses by Adding Extra Matter Fields

The renormalization group flow of soft supersymmetry breaking masses is sensitive to the field contents of the theory one considers. We point out that the addition of extra vector-like matter fields to the minimal supersymmetric standard model raises the masses of squarks and sleptons relative to those of gauginos. We discuss its phenomenological implications. Besides an obvious effect to the superparticle mass spectrum, we find that radiative corrections from heavier stop loops increase the lightest CP-even Higgs boson mass. We also discuss impact on models with no-scale boundary conditions. It turns out that, unlike the minimal case, staus can become heavier than a B-ino like neutralino, which is cosmologically favored.

hep-ph↗

arXiv2003

Cosmic String from D-term Inflation and Curvaton

We study effects of the cosmic string in the D-term inflation model on the cosmic microwave background (CMB) anisotropy. In the D-term inflation model, gauged cosmic string is usually formed, which may significantly affect the CMB anisotropy. We see that its study imposes important constraint. In order to realize the minimal model of D-term inflation, we see that the coupling constant λin the superpotential generating the inflaton potential should be significantly small, λ\lesssim O(10^{-4}-10^{-5}). We also discuss that a consistent scenario of the D-term inflation with λ\sim 1 can be constructed by adopting the curvaton mechanism where the cosmic density fluctuations are generated by a primordial fluctuation of a late-decaying scalar field other than the inflaton.

hep-ph↗

arXiv2002

Recent Muon g-2 Result in Deflected Anomaly-Mediated Supersymmetry Breaking

We study the deflected anomaly-mediated supersymmetry breaking (AMSB) scenario in the light of the recent result of the muon g-2 from Brookhaven E821 experiment. The E821 result suggests the deviation from the SM prediction, though there remain unsettled uncertainties. We find that the supersymmetric contribution to the muon g-2 can be \mathcal{O}(10^{-9}), large enough to fill the deviation, with other experimental constraints satisfied. In particular, the Higgs mass and b \to s γput severe constraints on the model and large \tanβis favored to enhance the muon g-2.

hep-ph↗

arXiv2002

Phenomenology of Minimal Supergravity with Vanishing A and B Soft Supersymmetry-Breaking Parameters

The ansatz of vanishing A and B parameters eliminates CP violating complex phases in soft supersymmetry-breaking parameters of the minimal supersymmetric standard model, and thus provides a simple solution to the supersymmetry CP problem. Phenomenological implications of this ansatz are investigated in the framework of minimal supergravity. We show that electroweak symmetry breakdown occurs, predicting relatively large \tan β. The ansatz survives the Higgs mass bound as well as the b \to s γconstraint if the universal gaugino mass is larger than 300 GeV. We also find that the supersymmetric contribution to the anomalous magnetic moment of muon lies in an experimentally interesting region of order 10^{-9} in a large portion of the parameter space.

hep-ph↗

arXiv2001

Muon Magnetic Dipole Moment and Higgs Mass in Supersymmetric SU(5) Models

We study the muon magnetic dipole moment and the Higgs mass in the framework of the supersymmetric SU(5) models. In this analysis, all the relevant parameters in the Lagrangian are taken to be free; in particular, assumption of the universal scalar mass is not adopted. Negative search for the Higgs boson at the LEP II experiment sets an important constraint on the supersymmetric contribution to the muon magnetic dipole moment a_μ(SUSY). It is shown that, for a fixed value of the lightest Higgs mass, the maximum possible value of a_μ(SUSY) becomes significantly larger in the general SU(5) case compared to the case of the universal scalar mass (i.e., the case of the so-called ``CMSSM''). We also point out that, if we take relatively large value of the trilinear scalar couplings, the constraint from the Higgs mass is drastically relaxed. In this case, a_μ(SUSY) can be as large as \sim 50\times 10^{-10} even for small value of \tanβ(say, for \tanβ=5).

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