400 research outputs found

    Quantum Mechanical Breaking of Local GL(4) Invariance

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    We consider the gravitational coupling of a scalar field, in a reformulation of General Relativity exhibiting local GL(4) invariance at the classical level. We compute the one-loop contribution of the scalar to the quantum effective potential of the vierbein and find that it does not have GL(4) invariance. The minima of the effective potential occur for a vierbein which is proportional to the unit matrix.Comment: 9 pages, plain-TeX, no figure

    A model for the continuous q-ultraspherical polynomials

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    We provide an algebraic interpretation for two classes of continuous qq-polynomials. Rogers' continuous qq-Hermite polynomials and continuous qq-ultraspherical polynomials are shown to realize, respectively, bases for representation spaces of the qq-Heisenberg algebra and a qq-deformation of the Euclidean algebra in these dimensions. A generating function for the continuous qq-Hermite polynomials and a qq-analog of the Fourier-Gegenbauer expansion are naturally obtained from these models

    Tests of Complete Positivity in Fiber Optics

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    We consider the propagation of polarized photons in optical fibers under the action of randomly generated noise. In such situation, the change in time of the photon polarization can be described by a quantum dynamical semigroup. We show that the hierarchy among the decay constants of the polarization density matrix elements as prescribed by complete positivity can be experimentally probed using standard laboratory set-ups.Comment: 10 pages, LaTe

    Open system approach to neutrino oscillations

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    Neutrino oscillations are studied in the general framework of open quantum systems by means of extended dynamics that take into account possible dissipative effects. These new phenomena induce modifications in the neutrino oscillation pattern that in general can be parametrized by means of six phenomenological constants. Although very small, stringent bounds on these parameters are likely to be given by future planned neutrino experiments.Comment: 15 pages, plain-TeX, to appear in JHE

    Complete positivity and neutron interferometry

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    We analyze the dynamics of neutron beams in interferometry experiments using quantum dynamical semigroups. We show that these experiments could provide stringent limits on the non-standard, dissipative terms appearing in the extended evolution equations.Comment: 12 pages, plain Te

    Massless neutrino oscillations

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    Quantum dynamical semigroups provide a general framework for studying the evolution of open systems. Neutrino propagation both in vacuum and in matter can be analyzed using these techniques: they allow a consistent treatment of non-standard, dissipative effects that can alter the pattern of neutrino oscillations. In particular, initially massless neutrinos can give rise to a nonvanishing flavour transition probability, involving in addition the Majorana CP-violating mixing phase.Comment: 27 pages, plain-TeX, no figure

    More on the q-oscillator algebra and q-orthogonal polynomials

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    Properties of certain qq-orthogonal polynomials are connected to the qq-oscillator algebra. The Wall and qq-Laguerre polynomials are shown to arise as matrix elements of qq-exponentials of the generators in a representation of this algebra. A realization is presented where the continuous qq-Hermite polynomials form a basis of the representation space. Various identities are interpreted within this model. In particular, the connection formula between the continuous big qq-Hermite polynomials and the continuous qq-Hermite polynomials is thus obtained, and two generating functions for these last polynomials are algebraically derived

    Asymptotic Entanglement of Two Independent Systems in a Common Bath

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    Two, non-interacting systems immersed in a common bath and evolving with a Markovian, completely positive dynamics can become initially entangled via a purely noisy mechanism. Remarkably, for certain, phenomenologically relevant environments, the quantum correlations can persist even in the asymptotic long-time regime.Comment: 10 pages, LaTe
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