Joachim Hilgert

  1. Integration on Non-Compact Supermanifolds.

    Authors: Alexander Alldridge, Joachim Hilgert, Wolfgang Palzer
    Subjects: Differential Geometry
    Abstract

    We investigate the Berezin integral of non-compactly supported quantities. In
    the framework of supermanifolds with corners, we give a general, explicit and
    coordinate-free repesentation of the boundary terms introduced by an arbitrary
    change of variables. As a corollary, a general Stokes's theorem is derived -
    here, the boundary integral contains transversal derivatives of arbitrarily
    high order.

  2. Invariant Berezin integration on homogeneous supermanifolds.

    Authors: Alexander Alldridge, Joachim Hilgert
    Subjects: Differential Geometry
    Abstract

    Let G be a Lie supergroup and H a closed subsupergroup. We study the
    unimodularity of the homogeneous supermanifold G/H, i.e. the existence of
    G-invariant sections of its Berezinian line bundle. To that end, we express
    this line bundle as a G-equivariant associated bundle of the principal H-bundle
    G over G/H. We also study the fibre integration of Berezinians on oriented
    fibre bundles. As an application, we prove a formula of `Fubini' type: the
    invariant integral over G can be expressed (up to sign) by a succesive
    invariant integration over H and G/H.

  3. Chevalley's restriction theorem for reductive symmetric superpairs.

    Authors: Alexander Alldridge, Joachim Hilgert, Martin R. Zirnbauer
    Subjects: Representation Theory
    Abstract

    Let (g,k) be a reductive symmetric superpair of even type, i.e. so that there
    exists an even Cartan subspace a in p. The restriction map S(p^*)^k->S(a^*)^W
    where W=W(g_0:a) is the Weyl group, is injective. We determine its image
    explicitly.

  4. Patterson--Sullivan distributions for rank one symmetric spaces of the noncompact type.

    Authors: Joachim Hilgert, Michael Schroeder
    Subjects: Spectral Theory
    Abstract

    There is a remarkable relation between two kinds of phase space distributions
    associated to eigenfunctions of the Laplacian of a compact hyperbolic manifold:
    It was observed in \cite{AZ} that for compact hyperbolic surfaces
    $X_{\Gamma}=\Gamma\backslash\mathbb{H}$ Wigner distributions $\int_{S^*
    X_{\Gamma}} a dW_{ir_j} = < Op(a)\phi_{ir_j},\phi_{ir_j}>_{L^2(X_{\Gamma})}$
    and Patterson--Sullivan distributions $PS_{ir_j}$ are asymptotically equivalent
    as $r_j\to\infty$.

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