132 research outputs found

    Imminent Phenomenology of a Minimal Gauge-Mediated Model

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    We calculate the inclusive branching ratio for B--> X_s gamma, the inclusive branching ratios and asymmetries for B--> X_s l+ l- and the anomalous magnetic moment g-2 of the muon, within a minimal gauge-mediated SUSY-breaking model which naturally generates a large ratio tan(beta) of Higgs field vacuum expectation values. These predictions are highly correlated with each other, depending on only two fundamental parameters: the superpartner mass scale and the logarithm of a common messenger mass. The predictions for B--> X_s gamma decay and g-2 are in somewhat better agreement with current experiments than the standard model, but a much sharper comparison will soon be possible using new measurements now in progress or under analysis. Moreover we predict large deviations in B--> X_s e+ e- and B--> X_s mu+ mu- asymmetries, and somewhat smaller ones in B--> X_s e+ e- and B--> X_s tau+ tau- branching ratios, which will be detectable in hadronic colliders

    The Unified Minimal Supersymmetric Model with Large Yukawa Couplings

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    The consequences of assuming the third-generation Yukawa couplings are all large and comparable are studied in the context of the minimal supersymmetric extension of the standard model. General aspects of the RG evolution of the parameters, theoretical constraints needed to ensure proper electroweak symmetry breaking, and experimental and cosmological bounds on low-energy parameters are presented. We also present complete and exact semi-analytic solutions to the 1-loop RG equations. Focusing on SU(5) or SO(10) unification, we analyze the relationship between the top and bottom masses and the superspectrum, and the phenomenological implications of the GUT conditions on scalar masses. Future experimental measurements of the superspectrum and of the strong coupling will distinguish between various GUT-scale scenarios. And if present experimental knowledge is to be accounted for most naturally, a particular set of predictions is singled out.Comment: 59 pages, plus 10 postscript figures and 2 postscript tables uuencoded and attached as part 2, plain LaTeX + epsf macro

    Materials Characterization Using High-Frequency Atomic Force Microscopy and Friction Force Microscopy

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    During the last decade, Atomic Force Microscopy (AFM) has been widely used to image the topography of various surfaces with corrugations down to the atomic scale [1,2]. Since then, development of new techniques based on AFM has been conducted to evaluate physical, chemical or mechanical surface properties [3]. We describe the use of near-field acoustic microscopy, based on AFM and hereafter referred to as Acoustic Microscopy by Atomic Force Microscopy (AFAM), as it has been developed earlier [4]. The relevance of this new scanning probe microscopy for high-resolution nondestructive testing and evaluation purposes is pointed out. It is shown that AFAM is capable of measuring elasticity on surfaces with a spatial resolution of less than 100 nm. Subsurface elastic properties and subsurface microdefect characterization can be performed by this technique. The high frequency Friction Force Microscopy (FFM) image, hereafter called Acoustic Friction Force Micropscopy (AFFM), reveals information different from the conventionally taken friction force image. We describe experimental and theoretical aspects of high-frequency atomic force and friction force microscopy

    Dynamic Behavior in Piezoresponse Force Microscopy

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    Frequency dependent dynamic behavior in Piezoresponse Force Microscopy (PFM) implemented on a beam-deflection atomic force microscope (AFM) is analyzed using a combination of modeling and experimental measurements. The PFM signal comprises contributions from local electrostatic forces acting on the tip, distributed forces acting on the cantilever, and three components of the electromechanical response vector. These interactions result in the bending and torsion of the cantilever, detected as vertical and lateral PFM signals. The relative magnitudes of these contributions depend on geometric parameters of the system, the stiffness and frictional forces of tip-surface junction, and operation frequencies. The dynamic signal formation mechanism in PFM is analyzed and conditions for optimal PFM imaging are formulated. The experimental approach for probing cantilever dynamics using frequency-bias spectroscopy and deconvolution of electromechanical and electrostatic contrast is implemented.Comment: 65 pages, 15 figures, high quality version available upon reques

    Gravitational Smearing of Minimal Supersymmetric Unification Predictions

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    A short and mean paper.Comment: 10 pages total + 1 postscript figure (included), revised: all lines are TRULY < 70 characters long (try it!); LBL-32905, UCB-PTH-92/3

    Casimir and van der Waals force between two plates or a sphere (lens) above a plate made of real metals

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    The Casimir and van der Waals forces acting between two metallic plates or a sphere (lens) above a plate are calculated accounting for the finite conductivity of the metals. The simple formalism of surface modes is briefly presented which allows the possibility to obtain the generalization of Lifshitz results for the case of two semi-spaces covered by the thin layers. Additional clarifications of the regularization procedure provides the means to obtain reliable results not only for the force but also for the energy density. This, in turn, leads to the value of the force for the configuration of a sphere (lens) above a plate both of which are covered by additional layers. The Casimir interaction between Al and Au test bodies is recalculated using the optical tabulated data for the complex refractive index of these metals. The computations turn out to be in agreement with the perturbation theory up to the fourth order in relative penetration depth of electromagnetic zero point oscillations into the metal. The disagreements between the results recently presented in the literature are resolved. The Casimir force between Al bodies covered by the thin Au layers is computed and the possibility to neglect spatial dispersion effects is discussed as a function the layer thickness. The van der Waals force is calculated including the transition region to the Casimir force. The pure non-retarded van der Waals force law between Al and Au bodies is shown to be restricted to a very narrow distance interval from 0.5 nm to (2--4) nm. New, more exact, values of the Hamaker constant for Al and Au are determined.Comment: 5 figure

    An Updated Description of Heavy-Hadron Interactions in Geant-4

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    Exotic stable massive particles (SMP) are proposed in a number of scenarios of physics beyond the Standard Model. It is important that LHC experiments are able both to detect and extract the quantum numbers of any SMP with masses around the TeV scale. To do this, an understanding of the interactions of SMPs in matter is required. In this paper a Regge-based model of R-hadron scattering is extended and implemented in Geant-4. In addition, the implications of RR-hadron scattering for collider searches are discussed
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