Karl-Hermann Neeb

  1. Categories of unitary representations of Banach-Lie supergroups and restriction functors.

    Authors: Karl-Hermann Neeb, Hadi Salmasian, Stephane Merigon
    Subjects: Representation Theory
    Abstract

    We prove that the categories of smooth and analytic unitary representations
    of Banach--Lie supergroups are well-behaved under restriction functors, in the
    sense that the restriction of a representation to an integral subsupergroup is
    well-defined. We also prove that the category of analytic representations is
    isomorphic to a subcategory of the category of smooth representations. These
    facts are needed as a crucial first step to a rigorous treatment of the
    analytic theory of unitary representations of Banach--Lie supergroups.

  2. On Analytic Vectors for Unitary Representations of Infinite Dimensional Lie Groups.

    Authors: Karl-Hermann Neeb
    Subjects: Representation Theory
    Abstract

    Let $G$ be a 1-connected Banach-Lie group or, more generally, a BCH--Lie
    group. On the complex enveloping algebra $U_\C(\g)$ of its Lie algebra $\g$ we
    define the concept of an analytic functional and show that every positive
    analytic functional $\lambda$ is integrable in the sense that it is of the form
    $\lambda(D) = \la \dd\pi(D)v, v\ra$ for an analytic vector $v$ of a unitary
    representation of $G$. On the way to this result we derive criteria for the
    integrability of *-representations of infinite dimensional Lie algebras of
    unbounded operators to unitary group representations.

  3. Infinite Tensor Products of C_0(R): Towards a Group Algebra for R^\infty.

    Authors: Karl-Hermann Neeb, Hendrik Grundling
    Subjects: Operator Algebras
    Abstract

    The construction of an infinite tensor product of the C*-algebra C_0(R) is
    not obvious, because it is nonunital, and it has no nonzero projection. Based
    on a choice of an approximate identity, we construct here an infinite tensor
    product of C_0(R), denoted L_V. We use this to construct (partial) group
    algebras for the full continuous unitary representation theory of the group
    R^(N) = the infinite sequences with real entries, of which only finitely many
    entries are nonzero.

  4. Localization via Automorphisms of the CARs. Local gauge invariance.

    Authors: Karl-Hermann Neeb, Hendrik Grundling
    Subjects: Mathematical Physics
    Abstract

    The classical matter fields are sections of a vector bundle E with base
    manifold M. The space L^2(E) of square integrable matter fields w.r.t. a
    locally Lebesgue measure on M, has an important module action of C_b^\infty(M)
    on it. This module action defines restriction maps and encodes the local
    structure of the classical fields. For the quantum context, we show that this
    module action defines an automorphism group on the algebra A, of the canonical
    anticommutation relations on L^2(E), with which we can perform the analogous
    localization. That is, the net structure of the CAR, A, w.r.t.

  5. Semibounded representations and invariant cones in infinite dimensional Lie algebras.

    Authors: Karl-Hermann Neeb
    Subjects: Representation Theory
    Abstract

    A unitary representation of a, possibly infinite dimensional, Lie group $G$
    is called semi-bounded if the corresponding operators $i\dd\pi(x)$ from the
    derived representations are uniformly bounded from above on some non-empty open
    subset of the Lie algebra $\g$. In the first part of the present paper we
    explain how this concept leads to a fruitful interaction between the areas of
    infinite dimensional convexity, Lie theory, symplectic geometry (momentum maps)
    and complex analysis.

  6. Borel--Weil Theory for Groups over Commutative Banach Algebras.

    Authors: Christoph Muller, Karl-Hermann Neeb, Henrik Seppanen
    Subjects: Representation Theory
    Abstract

    Let $\cA$ be a commutative unital Banach algebra, $\g$ be a semisimple
    complex Lie algebra and $G(\cA)$ be the 1-connected Banach--Lie group with Lie
    algebra $\g \otimes \cA$. Then there is a natural concept of a parabolic
    subgroup $P(\cA)$ of $G(\cA)$ and we obtain generalizations $X(\cA) :=
    G(\cA)/P(\cA)$ of the generalized flag manifolds. In this note we provide an
    explicit description of all homogeneous holomorphic line bundles over $X(\cA)$
    with non-zero holomorphic sections.

  7. Borel--Weil Theory for Groups over Commutative Banach Algebras.

    Authors: Christoph Muller, Karl-Hermann Neeb, Henrik Seppanen
    Subjects: Representation Theory
    Abstract

    Let $\cA$ be a commutative unital Banach algebra, $\g$ be a semisimple
    complex Lie algebra and $G(\cA)$ be the 1-connected Banach--Lie group with Lie
    algebra $\g \otimes \cA$. Then there is a natural concept of a parabolic
    subgroup $P(\cA)$ of $G(\cA)$ and we obtain generalizations $X(\cA) :=
    G(\cA)/P(\cA)$ of the generalized flag manifolds. In this note we provide an
    explicit description of all homogeneous holomorphic line bundles over $X(\cA)$
    with non-zero holomorphic sections.

RSS-материал