1,721,159 research outputs found

    A Doob h-Transform of the Gross-Pitaevskii Hamiltonian

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    We perform a Doob h-transformation of the N-body Hamiltonian for N trapped interacting Bose particles starting from the unique real strictly positive ground state. This identifies the unitarily equivalent Markov generator describing the N interacting diffusion processes. By applying the convergence results coming from the Gross-Pitaevskii (GP) scaling limit to the energy form associated with this Markov generator we obtain the asymptotic generator uniquely corresponding to the GP Hamiltonian, which has been rigorously derived from the N-body Hamiltonian by performing the same scaling limit. Our asymptotic generator is a non linear diffusion generator with a killing rate governed by the GP order parameter. The associated stochastic process properly describes the single particle motion in the Bose-Einstein condensate including the self-interaction which acts here as a probability density-dependent killing rate. Finally, in a one-dimensional setting, we discuss under which conditions the process conditioned to survival converges to a quasi-stationary distribution having density with respect to the speed measure given by the principal eigenfunction of the diffusion generator with killing

    Complex Dirichlet Forms: Non symmetric Diffusion Processes and Schoedinger Operators

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    The concept of complex Dirichlet forms epsilon_c resp.operators L_c in complex weighted L^2-spaces is introduced. Perturbations of classical Dirichlet forms by forms associated with complex first-order differential operators provide examples of complex Dirichlet forms. Complex Dirichlet operators L_c are unitarily equivalent with (a family of) Schroedinger operators with electromagnetic potentials. To epsilon_c there is associated a pair of real-valued non symmetric Dirichlet forms on the corresponding real weighted L^2-spaces, which in turn are associated with (non-symmetric) diffusion processes. Results by Stannat on non symmetric Dirichlet forms and their perturbations can be used for discussing the essential self-adjointness of L_c. New closability criteria for (perturbation of) non symmetric Dirichlet forms are obtained

    Some results for the exponential interaction in two or more dimensions

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    We show that for the regularized exponential interaction \lambda :e^{\alpha \varphi_x in dd space-time dimensions the Schwinger functions converge, upon cut-off removal, to the Schwinger functions for the free field if d>2d>2 for all α\alpha or if d=2d=2 for all α\alpha such that $|\alpha|>\alpha_0>0

    The exponential interaction in RdR^d

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    We prove that removing the ultraviolet cut-off the exponential interaction field theory becomes trivial in space-time dimension >2 at all non zero couplings and in dimension 2 at large enough couplings

    Non-symmetric diffusions and related Hamiltonians

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    We exhibit a unitary correspondence between (equivalence classes) of Hamiltonians H (Φ, A), involving electromagnetic potentials (A, Φ), and generators of 'bi-directional' Markov semigroups associated with non-symmetric diffusion processes

    An extended Kohonen phonetic map

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    This letter contains an approach to improve the Kohonen phonetic typewriter [1] by enlarging the phonetic objects which are used to label the phonetic map: the transitions between phonemes are introduced as new labels of neurons
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