Functional integration on spaces of connections

Stephen F. Sawin, John C. Baez

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Abstract

<p> Suppose that <em> G </em> is a compact connected Lie group and <em> P </em> &rarr; <em> M </em> is a smooth principal <em> G </em> -bundle. We define a &ldquo;cylinder function&rdquo; on the space of smooth connections on <em> P </em> to be a continuous complex function of the holonomies along finitely many piecewise smoothly immersed curves in <em> M </em> . Completing the algebra of cylinder functions in the sup norm, we obtain a commutative C*-algebra Fun(). Let a &ldquo;generalized measure&rdquo; on be a bounded linear functional on Fun(). We construct a generalized measure <em> &mu; </em> <sub> 0 </sub> on that is invariant under all automorphisms of the bundle <em> P </em> (not necessarily fixing the base <em> M </em> ). This result extends previous work which assumed <em> M </em> was real-analytic and used only piecewise analytic curves in the definition of cylinder functions. As before, any graph with <em> n </em> edges embedded in <em> M </em> determines a C*-subalgebra of Fun() isomorphic to <em> C </em> ( <em> G <sup> n </sup> </em> ), and the generalized measure <em> &mu; </em> <sub> 0 </sub> : Fun()&rarr; restricts to the linear functional on <em> C </em> ( <em> G <sup> n </sup> </em> ) given by integration against normalized Haar measure on <em> G <sup> n </sup> </em> . Our result implies that the group of gauge transformations acts as unitary operators on <em> L </em> <sup> 2 </sup> (), the Hilbert space completion of Fun() in the norm &Vert; <em> F </em> &Vert; <sub> 2 </sub> = <em> &mu; </em> <sub> 0 </sub> (| <em> F </em> | <sup> 2 </sup> ) <sup> 1/2 </sup> . Using &ldquo;spin networks,&rdquo; we construct explicit functions spanning the subspace <em> L </em> <sup> 2 </sup> (/)&sube; <em> L </em> <sup> 2 </sup> () consisting of vectors invariant under the action of .</p>
Original languageAmerican English
JournalJournal of Functional Analysis
Volume150
DOIs
StatePublished - Jan 1 1997

Disciplines

  • Computer Sciences
  • Physical Sciences and Mathematics

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