21,503 research outputs found

    Electric Dipole Moments in the Generic Supersymmetric Standard Model

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    The generic supersymmetric standard model is a model built from a supersymmetrized standard model field spectrum the gauge symmetries only. The popular minimal supersymmetric standard model differs from the generic version in having R-parity imposed by hand. We review an efficient formulation of the model and some of the recently obtained interesting phenomenological features, focusing on one-loop contributions to fermion electric dipole moments.Comment: 1+7 pages Revtex 3 figures incoporated; talk at NANP'0

    Neutrino Oscillations from Supersymmetry without R-parity - Its Implications on the Flavor Structure of the Theory

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    We discuss here some flavor structure aspects of the complete theory of supersymmetry without R-parity addressed from the perspective of fitting neutrino oscillation data based on the recent Super-Kamiokande result. The single-VEV parametrization of supersymmetry without R-parity is first reviewed, illustrating some important features not generally appreciated. For the flavor structure discussions, a naive, flavor model independent, analysis is presented, from which a few interesting things can be learned.Comment: 1+10 pages latex, no figure; Invited talk at NANP 99 conference, Dubna (Jun 28 - Jul 3) --- submission for the proceeding

    Little Higgs Model Completed with a Chiral Fermionic Sector

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    The implementation of the little Higgs mechanism to solve the hierarchy problem provides an interesting guiding principle to build particle physics models beyond the electroweak scale. Most model building works, however, pay not much attention to the fermionic sector. Through a case example, we illustrate how a complete and consistent fermionic sector of the TeV effective field theory may actually be largely dictated by the gauge structure of the model. The completed fermionic sector has specific flavor physics structure, and many phenomenological constraints on the model can thus be obtained beyond gauge, Higgs, and top physics. We take a first look on some of the quark sector constraints.Comment: 14 revtex pages with no figure, largely a re-written version of hep-ph/0307250 with elaboration on flavor sector FCNC constraints; accepted for publication in Phys.Rev.

    Quantized Casimir Force

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    We investigate the Casimir effect between two-dimensional electron systems driven to the quantum Hall regime by a strong perpendicular magnetic field. In the large separation (d) limit where retardation effects are essential we find i) that the Casimir force is quantized in units of 3\hbar c \alpha^2/(8\pi^2 d^4), and ii) that the force is repulsive for mirrors with same type of carrier, and attractive for mirrors with opposite types of carrier. The sign of the Casimir force is therefore electrically tunable in ambipolar materials like graphene. The Casimir force is suppressed when one mirror is a charge-neutral graphene system in a filling factor \nu=0 quantum Hall state.Comment: 4.2 page

    New Results for Diffusion in Lorentz Lattice Gas Cellular Automata

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    New calculations to over ten million time steps have revealed a more complex diffusive behavior than previously reported, of a point particle on a square and triangular lattice randomly occupied by mirror or rotator scatterers. For the square lattice fully occupied by mirrors where extended closed particle orbits occur, anomalous diffusion was still found. However, for a not fully occupied lattice the super diffusion, first noticed by Owczarek and Prellberg for a particular concentration, obtains for all concentrations. For the square lattice occupied by rotators and the triangular lattice occupied by mirrors or rotators, an absence of diffusion (trapping) was found for all concentrations, except on critical lines, where anomalous diffusion (extended closed orbits) occurs and hyperscaling holds for all closed orbits with {\em universal} exponents df=74{\displaystyle{d_f = \frac{7}{4}}} and Ï„=157{\displaystyle{\tau = \frac{15}{7}}}. Only one point on these critical lines can be related to a corresponding percolation problem. The questions arise therefore whether the other critical points can be mapped onto a new percolation-like problem, and of the dynamical significance of hyperscaling.Comment: 52 pages, including 18 figures on the last 22 pages, email: [email protected]

    Correlations and fluctuations of a confined electron gas

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    The grand potential Ω\Omega and the response R=−∂Ω/∂xR = - \partial \Omega /\partial x of a phase-coherent confined noninteracting electron gas depend sensitively on chemical potential μ\mu or external parameter xx. We compute their autocorrelation as a function of μ\mu, xx and temperature. The result is related to the short-time dynamics of the corresponding classical system, implying in general the absence of a universal regime. Chaotic, diffusive and integrable motions are investigated, and illustrated numerically. The autocorrelation of the persistent current of a disordered mesoscopic ring is also computed.Comment: 12 pages, 1 figure, to appear in Phys. Rev.

    Analysis of Microstrip Lines with Alternative Implementation of Conductors and Superconductors

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    An analysis of microstrip line structures in which either the strip or the ground plane or both are made of a high Tc superconductor is presented. The effect of implementation of a superconductor to the strip and the ground plane is explained with the calculation of a conductor loss of the structure by the Phenomenological Loss Equivalence Method (PEM). The theoretical values are compared with the experimental results from a ring resonator which is made of a gold ground plane and a high Tc superconductor, YBa2Cu3O(7-x), strip

    Lattice vibrations and structural instability in Cesium near the cubic to tetragonal transition

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    Under pressure cesium undergoes a transition from a high-pressure fcc phase (Cs-II) to a collapsed fcc phase (Cs-III) near 4.2GPa. At 4.4GPa there follows a transition to the tetragonal Cs-IV phase. In order to investigate the lattice vibrations in the fcc phase and seek a possible dynamical instability of the lattice, the phonon spectra of fcc-Cs at volumes near the III-IV transition are calculated using Savrasov's density functional linear-response LMTO method. Compared with quasiharmonic model calculations including non-central interatomic forces up to second neighbours, at the volume V/V0=0.44V/V_0= 0.44 (V0V_0 is the experimental volume of bcc-Cs with a0a_0=6.048{\AA}), the linear-response calculations show soft intermediate wavelength T[11ˉ0][ξξ0]T_{[1\bar{1}0]}[{\xi}{\xi}0] phonons. Similar softening is also observed for short wavelength L[ξξξ]L[\xi\xi\xi] and L[00ξ]L[00\xi] phonons and intermediate wavelength L[ξξξ]L[\xi\xi\xi] phonons. The Born-von K\'{a}rm\'{a}n analysis of dispersion curves indicates that the interplanar force constants exhibit oscillating behaviours against plane spacing nn and the large softening of intermediate wavelength T[11ˉ0][ξξ0]T_{[1\bar{1}0]}[{\xi}{\xi}0] phonons results from a negative (110)-interplanar force-constant Φn=2\Phi_{n=2}. The frequencies of the T[11ˉ0][ξξ0]T_{[1\bar{1}0]}[{\xi}{\xi}0] phonons with ξ\xi around 1/3 become imaginary and the fcc structure becomes dynamically unstable for volumes below 0.41V00.41V_0. It is suggested that superstructures corresponding to the q≠0\mathbf{q}{\neq}0 soft mode should be present as a precursor of tetragonal Cs-IV structure.Comment: 12 pages, 5 figure

    The narrow X-ray tail and double H-alpha tails of ESO 137-002 in Abell 3627

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    We present the analysis of a deep Chandra observation of a ~2L_* late-type galaxy, ESO 137-002, in the closest rich cluster A3627. The Chandra data reveal a long (>40 kpc) and narrow tail with a nearly constant width (~3 kpc) to the southeast of the galaxy, and a leading edge ~1.5 kpc from the galaxy center on the upstream side of the tail. The tail is most likely caused by the nearly edge-on stripping of ESO 137-002's ISM by ram pressure, compared to the nearly face-on stripping of ESO 137-001 discussed in our previous work. Spectral analysis of individual regions along the tail shows that the gas throughout it has a rather constant temperature, ~1 keV, very close to the temperature of the tails of ESO 137-001, if the same atomic database is used. The derived gas abundance is low (~0.2 solar with the single-kT model), an indication of the multiphase nature of the gas in the tail. The mass of the X-ray tail is only a small fraction (<5%) of the initial ISM mass of the galaxy, suggesting that the stripping is most likely at an early stage. However, with any of the single-kT, double-kT and multi-kT models we tried, the tail is always "over-pressured" relative to the surrounding ICM, which could be due to the uncertainties in the abundance, thermal vs. non-thermal X-ray emission, or magnetic support in the ICM. The H-alpha data from SOAR show a ~21 kpc tail spatially coincident with the X-ray tail, as well as a secondary tail (~12 kpc long) to the east of the main tail diverging at an angle of ~23 degrees and starting at a distance of ~7.5 kpc from the nucleus. At the position of the secondary H-alpha tail, the X-ray emission is also enhanced at the ~2 sigma level. We compare the tails of ESO 137-001 and ESO 137-002, and also compare the tails to simulations. Both the similarities and differences of the tails pose challenges to the simulations. Several implications are briefly discussed.Comment: 15 pages, 6 figures, accepted for publication in Ap
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