3,470 research outputs found

    Predictions for the unitarity triangle angles in a new parametrization

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    A new approach to the parametrization of the CKM matrix, VV, is considered in which VV is written as a linear combination of the unit matrix II and a non-diagonal matrix UU which causes intergenerational-mixing, that is V=cosθI+isinθUV=\cos\theta I+i\sin\theta U. Such a VV depends on 3 real parameters including the parameter θ\theta. It is interesting that a value of θ=π/4\theta=\pi/4 is required to fit the available data on the CKM-matrix including CP-violation. Predictions of this fit for the angles α\alpha, β\beta and γ\gamma for the unitarity triangle corresponding to V11V13+V21V23+V31V33=0V_{11}V^*_{13} + V_{21} V^*_{23} +V_{31}V^*_{33} =0, are given. For θ\theta=π/4\pi/4, we obtain α=88.46\alpha=88.46^\circ, β=45.046\beta=45.046^\circ and γ=46.5\gamma=46.5^\circ. These values are just about in agreement, within errors, with the present data. It is very interesting that the unitarity triangle is expected to be approximately a right-angled, isosceles triangle. Our prediction sin2β=1\sin 2\beta = 1 is in excellent agreement with the value 0.99±0.15±0.050.99\pm 0.15\pm 0.05 reported by the Belle collaboration at the Lepton-Photon 2001 meeting.Comment: 11 pages, latex, no figure

    Spectra of phase point operators in odd prime dimensions and the extended Clifford group

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    We analyse the role of the Extended Clifford group in classifying the spectra of phase point operators within the framework laid out by Gibbons et al for setting up Wigner distributions on discrete phase spaces based on finite fields. To do so we regard the set of all the discrete phase spaces as a symplectic vector space over the finite field. Auxiliary results include a derivation of the conjugacy classes of ESL(2,FN){\rm ESL}(2, \mathbb{F}_N).Comment: Latex, 19page

    Hudson's Theorem for finite-dimensional quantum systems

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    We show that, on a Hilbert space of odd dimension, the only pure states to possess a non-negative Wigner function are stabilizer states. The Clifford group is identified as the set of unitary operations which preserve positivity. The result can be seen as a discrete version of Hudson's Theorem. Hudson established that for continuous variable systems, the Wigner function of a pure state has no negative values if and only if the state is Gaussian. Turning to mixed states, it might be surmised that only convex combinations of stabilizer states give rise to non-negative Wigner distributions. We refute this conjecture by means of a counter-example. Further, we give an axiomatic characterization which completely fixes the definition of the Wigner function and compare two approaches to stabilizer states for Hilbert spaces of prime-power dimensions. In the course of the discussion, we derive explicit formulas for the number of stabilizer codes defined on such systems.Comment: 17 pages, 3 figures; References updated. Title changed to match published version. See also quant-ph/070200

    The Schwinger SU(3) construction - I: Multiplicity problem and relation to induced representations

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    The Schwinger oscillator operator representation of SU(3) is analysed with particular reference to the problem of multiplicity of irreducible representations. It is shown that with the use of an Sp(2,R)Sp(2,R) unitary representation commuting with the SU(3) representation, the infinity of occurrences of each SU(3) irreducible representation can be handled in complete detail. A natural `generating representation' for SU(3), containing each irreducible representation exactly once, is identified within a subspace of the Schwinger construction; and this is shown to be equivalent to an induced representation of SU(3).Comment: Latex, 25 page

    Particle alignments and shape change in 66^{66}Ge and 68^{68}Ge

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    The structure of the NZN \approx Z nuclei 66^{66}Ge and 68^{68}Ge is studied by the shell model on a spherical basis. The calculations with an extended P+QQP+QQ Hamiltonian in the configuration space (2p3/22p_{3/2}, 1f5/21f_{5/2}, 2p1/22p_{1/2}, 1g9/21g_{9/2}) succeed in reproducing experimental energy levels, moments of inertia and QQ moments in Ge isotopes. Using the reliable wave functions, this paper investigates particle alignments and nuclear shapes in 66^{66}Ge and 68^{68}Ge. It is shown that structural changes in the four sequences of the positive- and negative-parity yrast states with even JJ and odd JJ are caused by various types of particle alignments in the g9/2g_{9/2} orbit. The nuclear shape is investigated by calculating spectroscopic QQ moments of the first and second 2+2^+ states, and moreover the triaxiality is examined by the constrained Hatree-Fock method. The changes of the first band crossing and the nuclear deformation depending on the neutron number are discussed.Comment: 18 pages, 21 figures; submitted to Phys. Rev.

    Quantum phase space distributions in thermofield dynamics

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    It is shown that the the quantum phase space distributions corresponding to a density operator ρ\rho can be expressed, in thermofield dynamics, as overlaps between the state ρ>\mid \rho > and "thermal" coherent states. The usefulness of this approach is brought out in the context of a master equation describing a nonlinear oscillator for which exact expressions for the quantum phase distributions for an arbitrary initial condition are derived.Comment: 17 pages, revtex, no figures. number of pages were incorrectly stated as 3 instead of 17. No other correction

    Linear amplification and quantum cloning for non-Gaussian continuous variables

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    We investigate phase-insensitive linear amplification at the quantum limit for single- and two-mode states and show that there exists a broad class of non-Gaussian states whose nonclassicality survives even at an arbitrarily large gain. We identify the corresponding observable nonclassical effects and find that they include, remarkably, two-mode entanglement. The implications of our results for quantum cloning outside the Gaussian regime are also addressed.Comment: published version with reference updat

    TOLERANCE SHOWN BY Rattus rattus TO AN ANTICOAGULANT RODENTICIDE

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    Apart from using 0.005% concentration, the recommended field dose of 0.025% of the anticoagulant is used along with an alternate food for individual rats for a varying number of days. Those that had survived were taken as tolerant, provided they showed an mg/kg intake beyond the tolerance limit, survived a six days of feeding, exhibited bait-shyness and did not exhibit hemorrhage after death. In determining the criteria for tolerance to an anticoagulant by a rat, one should take into account four composite factors. These are, six days of even 0.025% feeding, bait-shyness when alternate food is given, higher mg/kg intake than the tolerance level and a loss of intensive hemorrhage after death

    First-principles quantum dynamics in interacting Bose gases I: The positive P representation

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    The performance of the positive P phase-space representation for exact many-body quantum dynamics is investigated. Gases of interacting bosons are considered, where the full quantum equations to simulate are of a Gross-Pitaevskii form with added Gaussian noise. This method gives tractable simulations of many-body systems because the number of variables scales linearly with the spatial lattice size. An expression for the useful simulation time is obtained, and checked in numerical simulations. The dynamics of first-, second- and third-order spatial correlations are calculated for a uniform interacting 1D Bose gas subjected to a change in scattering length. Propagation of correlations is seen. A comparison is made to other recent methods. The positive P method is particularly well suited to open systems as no conservation laws are hard-wired into the calculation. It also differs from most other recent approaches in that there is no truncation of any kind.Comment: 21 pages, 7 figures, 2 tables, IOP styl
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