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    Symmetry breaking in quasi-1D Coulomb systems
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2010) Aizenman, Michael; Jansen, Sabine; Jung, Paul
    Let a high-dimensional random vector vecX can be represented as a sum of two components - a signa vecS, which belongs to some low-dimensional subspace mathcalS, and a noise component vecN. This paper presents a new approach for estimating the subspace mathcalS based on the ideas of the Non-Gaussian Component Analysis. Our approach avoids the technical difficulties that usually exist in similar methods - it doesn't require neither the estimation of the inverse covariance matrix of vecX nor the estimation of the covariance matrix of vecN
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    Fermionic and bosonic Laughlin state on thick cylinders
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2011) Jansen, Sabine
    We investigate a many-body wave function for particles on a cylinder known as Laughlin's function. It is the power of a Vandermonde determinant times a Gaussian. Our main result is: in a many-particle limit, at fixed radius, all correlation functions have a unique limit, and the limit state has a non-trivial period in the axial direction. The result holds regardless how large the radius is, for fermions as well as bosons. In addition, we explain how the algebraic structure used in proofs relates to a ground state perturbation series and to quasi-state decompositions, and we show that the monomer-dimer function introduced in an earlier work is an exact, zero energy, ground state of a suitable finite range Hamiltonian; this is interesting because of formal analogies with some quantum spin chains.