Hilbert C*-systems for actions of the circle group
Hellmut Baumgärtel, Alan L. Carey
October 10, 2000
The paper contains constructions of Hilbert systems for the action of the
circle group $T$ using subgroups of implementable Bogoljubov unitaries w.r.t.
Fock representations of the Fermion algebra for suitable data of the selfdual
framework: ${\mathcal H}$ is the reference Hilbert space, $\Gamma$ the conjugation
and $P$ a basis projection on ${\mathcal H}.$ The group $C(\text{spec} {\mathcal Z}\rightarrow T)$
of $T$-valued functions on $\text{spec} {\mathcal Z}$ turns out to be isomorphic to the
stabilizer of ${\mathcal A}$. In particular, examples are presented where the
center ${\mathcal Z}$ of the fixed point algebra ${\mathcal A}$ can be calculated
explicitly.
Keywords:
none