A Group Algebra for Inductive Limit Groups. Continuity Problems of the Canonical Commutation Relations

Given an inductive limit group where each is locally compact, and a continuous two-cocycle , we construct a C^*-algebra group algebra is imbedded in its multiplier algebra , and the representations of are identified with the strong operator continuous of G. If any of these representations are faithful, the above imbedding is faithful. When G is locally compact, is precisely , the twisted group algebra of G, and for these reasons we regard in the general case as a twisted group algebra for G. Applying this construction to the CCR-algebra over an infinite dimensional symplectic space (S,\,B),we realise the regular representations as the representation space of the C^*-algebra , and show that pointwise continuous symplectic group actions on (S,\, B) produce pointwise continuous actions on , though not on the CCR-algebra. We also develop the theory to accommodate and classify 'partially regular' representations, i.e. representations which are strong operator continuous on some subgroup H of G (of suitable type) but not necessarily on G, given that such representations occur in constrained quantum systems.     

A Family of Examples with Quantum Constraints

In Rep. Math. Phys. 35 (1995), 101, the authors describe a method for constructing directly (i.e. without using explicitly any field operator nor any concrete representation of the C*-algebra) nets of local C*-algebras associated to massless models with arbitrary helicity and that satisfy Haag–Kastler's axioms. In order to specify the sesquilinear and the symplectic form of the CAR- and CCR-algebras, respectively, a certain operator-valued function is introduced. This function is shown to be very useful in proving the covariance and causality of the net and it also codes the degenerate character of massless models with respect to massive models.It is the intention of this Letter to point out that the massless bosonic examples with helicity bigger than 0 fit completely into the general theory that Grundling and Hurst used to describe systems with gauge degeneracy.