Observation of modulation instability in a nonlinear magnetoinductive waveguide

We report numerical and experimental investigations into modulation instability in a nonlinear magnetoinductive waveguide. By numerical simulation we find that modulation instability occurs in an electrical circuit model of a magnetoinductive waveguide with third-order nonlinearity. We fabricate the nonlinear magnetoinductive waveguide for microwaves using varactor-loaded split-ring resonators and observe the generation of modulation instability in the waveguide. The condition for generating modulation instability in the experiment roughly agrees with that in the numerical analysis.Comment: 7 pages, 11 figure

Enhancement of second harmonic generation in a doubly resonant metamaterial

We investigate second harmonic (SH) generation in a doubly resonant metamaterial. We show that SH generation can be enhanced when the resonant condition is satisfied for the SH frequency as well as for the fundamental frequency. A unit cell of the doubly resonant metamaterial consists of two coupled resonators, one of which resonates at the fundamental frequency, whereas the other resonates around the SH frequency. We observe that the SH generation in the doubly resonant metamaterial is 4.6 times as large as that in a singly resonant metamaterial.Comment: 4 pages, 4 figure

Storage of electromagnetic waves in a metamaterial that mimics electromagnetically induced transparency

We propose a method for dynamically controlling the properties of a metamaterial that mimics electromagnetically induced transparency (EIT) by introducing varactor diodes to manipulate the structural symmetry of the metamaterial. Dynamic modulation of the EIT property enables the storage and retrieval of electromagnetic waves. We confirmed that the electromagnetic waves were stored and released, while maintaining the phase distribution in the propagating direction.Comment: 4 pages, 3 figures (Rapid Communication in Phys. Rev. B

TeV scale partial mirage unification and neutralino dark matter

We study the TeV scale partial mirage unification scenario, where the gluino and wino masses are degenerate around a TeV scale, but the bino mass is not degenerate. This scenario has phenomenologically interesting aspects. First, because of the degeneracy between the gluino and wino masses, this scenario does not have the little hierarchy problem, that is, the higgisino mass is around 150 GeV. The lightest superparticle is a mixture of the bino and higgsino, and can lead to a right amount of thermal relic density as a dark matter candidate

Higgs-mediated muon-electron conversion process in supersymmetric seesaw model

We study the effect of the Higgs-exchange diagram for the lepton flavor violating muon-electron conversion process in nuclei in the supersymmetric seesaw model. The contribution is significant for a large value of tan beta and a small value of a neutral heavy Higgs boson mass, in which case the ratio of the branching ratios of B(mu N -> e N) / B(mu -> e gamma) is enhanced. We also show that the target atom dependence of the conversion branching ratio provides information on the size of the Higgs exchange diagram.Comment: 12 pages, 2 figures, a reference adde

Natural Supersymmetry at the LHC

If the minimal supersymmetric standard model is the solution to the hierarchy problem, the scalar top quark (stop) and the Higgsino should weigh around the electroweak scale such as 200 GeV. A low messenger scale, which results in a light gravitino, is also suggested to suppress the quantum corrections to the Higgs mass parameters. Therefore the minimal model for natural supersymmetry is a system with stop/Higgsino/gravitino whereas other superparticles are heavy. We study the LHC signatures of the minimal system and discuss the discovery potential and methods for the mass measurements.Comment: 19 pages, 6 figures, 1 tabl