15,025 research outputs found

    Is there New Physics in B Decays ?

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    Rare decays of the BB meson are sensitive to new physics effects. Several experimental results on these decays have been difficult to understand within the standard model (SM) though more precise measurements and a better understanding of SM theory predictions are needed before any firm conclusions can be drawn. In this talk we try to understand the present data assuming the presence of new physics. We find that the data points to new physics of an extended Higgs sector and we present a two higgs doublet model with a 2-3 flavor symmetry in the down type quark sector that can explain the deviations from standard model reported in several rare B decays.Comment: 8 pages, Talk presented at Theory Canada II, Perimeter Institute, Waterloo, Canada. New references added and update

    On the Observability of "Invisible" / "Nearly Invisible" Charginos

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    It is shown that if the charginos decay into very soft leptons or hadrons + \not{E} due to degeneracy/ near- degeneracy with the LSP or the sneutrino, the observability of the recently proposed signal via the single photon (+ soft particles) + \not{E} channel crucially depends on the magnitude of the \SNU mass due to destructive interferences in the matrix element squared. If the \SNU's and, consequently, left-sleptons are relatively light, the size of the signal, previously computed in the limit \MSNU \to \infty only, is drastically reduced. We present the formula for the signal cross section in a model independent way and discuss the observability of the signal at LEP 192 and NLC energies.Comment: 27 pages, Late

    Embedding approach for dynamical mean field theory of strongly correlated heterostructures

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    We present an embedding approach based on localized basis functions which permits an efficient application of the dynamical mean field theory (DMFT) to inhomogeneous correlated materials, such as semi-infinite surfaces and heterostructures. In this scheme, the semi-infinite substrate leads connected to both sides of the central region of interest are represented via complex, energy-dependent embedding potentials that incorporate one-electron as well as many-body effects within the substrates. As a result, the number of layers which must be treated explicitly in the layer-coupled DMFT equation is greatly reduced. To illustrate the usefulness of this approach, we present numerical results for strongly correlated surfaces, interfaces, and heterostructures of the single-band Hubbard model.Comment: 8 pages, 4 figures; typos correcte

    A prohibition of equilibrium spin currents in multi-terminal ballistic devices

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    We show that in the multi-terminal ballistic devices with intrinsic spin-orbit interaction connected to normal metal contacts there are no equilibrium spin currents present at any given electron energy. Obviously, this statement holds also after the integration over all occupied states. Based on the proof of this fact, a number of scenarios involving nonequilibrium spin currents is identified and further analyzed. In particular, it is shown that an arbitrary two-terminal device cannot polarize transient current. The same is true for the output terminal of an N-terminal device when all N-1 inputs are connected in parallel.Comment: 3 pages, 1 figure; presented at the DARPA SPinS review (#Th-19), San Francisco, CA, October 25-28, 200

    Economics of different craft - gear combination in Orissa coast

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    After declaration of Exclusive Econonomic Zone, the Govt. of India took lot of developmental programmes in capture fisheries. But it is very difficult to formulate as well as to implement any programme unless and until we know the existing position prevailing in different coastal areas

    Productivity, profitability and income distribution in capture fishery - a case study in Orissa coast

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    In the literature on marine and inland fisheries very little attention has been focused on income generation by various craft-gear combinations, their productivity and the extent, nature and causes of fluctuations in their incomes. This study of the Orissa coast explores the consequences of mechanisation on income distribution between mechanised and non-mechanised fishing units

    Responses of stiffened plates with varying depth of stiffeners under uniform lateral loads

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    The main portion of ship’s structure is usually composed of stiffened plates. Under various loads applied to a ship, such as those due to cargo, buoyancy and waves, these stiffened plates are subjected to combined in plane and lateral loads. Longitudinal stiffeners attached to the plates may significantly increase the overall buckling loads of the resultant stiffened structures. In this work, eigen-buckling responses for a series of rectangular perfectly flat plates and longitudinally stiffened plates subjected to in plane axial forces for different depth of stiffeners are derived by finite element approach using general purpose software (ANSYS). Finally stiffener arrangements are explained in explicit form based on the results of numerical investigations of the non-linear behaviour of plates and stiffened plates

    Optimization of Process Parameters by Reliability-Based Uncertainty Modeling of Cold Rolling Process

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    Metal working processes can often be expressed in a reliability format. Information about present and anticipated reliabilities in metallurgical processes, in conjunction with decision models, provides a rational and powerful decision-making tool. In practice uncertainties arise in predicting service or lifetime loads in considering the variability in material properties, workmanship, process dimensions, environmental conditions, inspection test data, maintenance and so on. A wide range of materials with different elastic moduli, yield stresses, strain hardening and friction co-efficient constitute specific characteristics in a metal working process. Thus a metal working process may be defined as a collection of one or more related objects. Consequently, decisions related to rolling processes are based on uncertain or incomplete information. Finite element based process simulation can offer valuable guidelines on how the current process parameters should be modified to meet the requirements on the process and the product. This work represents a continued effort towards developing a sound methodology for modelling uncertainties in rolling process with reference to the reliability assessment. Based on the information obtained from the finite element simulation, investigations are conducted to assess the structural integrity of final product. The objective of this work is to use probabilistic methods to represent sources of uncertainty and to attain optimum set of points of rolling by iteration to achieve controlled microstructure of the finished product
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