1,438 research outputs found
Symmetry breaking boundary conditions and WZW orbifolds
Symmetry breaking boundary conditions for WZW theories are discussed. We
derive explicit formulae for the reflection coefficients in the presence of
boundary conditions that preserve only an orbifold subalgebra with respect to
an involutive automorphism of the chiral algebra. The characters and modular
transformations of the corresponding orbifold theories are computed. Both inner
and outer automorphisms are treated.Comment: 39 pages, LaTeX2
KMS weights on higher rank buildings
We extend some of the results of Carey-Marcolli-Rennie on modular index
invariants of Mumford curves to the case of higher rank buildings: we discuss
notions of KMS weights on buildings, that generalize the construction of graph
weights over graph C*-algebras.Comment: 25 pages, LaTeX, 4 jpg figure
Prime Type III Factors
We show that for each (0<\lambda <1), the free Araki-Woods factor of type
III(_{\lambda}) cannot be written as a tensor product of two diffuse von
Neumann algebras (i.e., is prime), and does not contain a Cartan subalgebra
Charged sectors, spin and statistics in quantum field theory on curved spacetimes
The first part of this paper extends the Doplicher-Haag-Roberts theory of
superselection sectors to quantum field theory on arbitrary globally hyperbolic
spacetimes. The statistics of a superselection sector may be defined as in flat
spacetime and each charge has a conjugate charge when the spacetime possesses
non-compact Cauchy surfaces. In this case, the field net and the gauge group
can be constructed as in Minkowski spacetime.
The second part of this paper derives spin-statistics theorems on spacetimes
with appropriate symmetries. Two situations are considered: First, if the
spacetime has a bifurcate Killing horizon, as is the case in the presence of
black holes, then restricting the observables to the Killing horizon together
with "modular covariance" for the Killing flow yields a conformally covariant
quantum field theory on the circle and a conformal spin-statistics theorem for
charged sectors localizable on the Killing horizon. Secondly, if the spacetime
has a rotation and PT symmetry like the Schwarzschild-Kruskal black holes,
"geometric modular action" of the rotational symmetry leads to a
spin-statistics theorem for charged covariant sectors where the spin is defined
via the SU(2)-covering of the spatial rotation group SO(3).Comment: latex2e, 73 page
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