TY - JOUR A1 - Baumgaertel, Hellmut A1 - Grundling, H. T1 - Superselection in the presence of constraints N2 - Superselection and constraints occur together in many gauge theories, and here we begin a study of such systems. Our main focus will be to analyze compatibility questions between constraining and superselection, and we will develop an example modelled on QED in which our framework is realized. We proceed from a generalization of Doplicher- Roberts superselection theory to the case of the nontrivial center, and a set of Dirac quantum constraints and find conditions under which the superselection structures will survive constraining in some form. This involves an analysis of the restriction and factorization of superselection structures. (c) 2005 American Institute of Physics Y1 - 2005 UR - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/13484 SN - 0022-2488 ER -