16 citations · 125 across the 34 of their papers we have counts for
36 papers
Charges in light cones and quenched infrared radiation
Detlev Buchholz, Fabio Ciolli, Giuseppe Ruzzi +1
The creation of electrically charged states and the resulting electromagnetic fields are considered in space-time regions in which such experiments can actually be carried out, nam…
Twisting factors and fixed-time models in quantum field theory
Ezio Vasselli
We construct a class of fixed-time models in which the commutations relations of a Dirac field with a bosonic field are non-trivial and depend on the choice of a given distribution…
Twisted tensor products of field algebras
Ezio Vasselli
Let A be a C*-algebra, h a Hilbert space and C the CAR algebra over h. We construct a twisted tensor product of A by C such that the two factors are not necessarily one in the rela…
Where charged sectors are localizable: a viewpoint from covariant cohomology
Fabio Ciolli, Giuseppe Ruzzi, Ezio Vasselli
Given a Haag-Kastler net on a globally hyperbolic spacetime, one can consider a family of regions where quantum charges are supposed to be localized. Assuming that the net fulfils…
Gauss's law, the manifestations of gauge fields, and their impact on local observables
Detlev Buchholz, Fabio Ciolli, Giuseppe Ruzzi +1
Within the framework of the universal algebra of the electromagnetic field, the impact of globally neutral configurations of external charges on the field is analyzed. External cha…
The universal algebra of the electromagnetic field III. Static charges and emergence of gauge fields
Detlev Buchholz, Fabio Ciolli, Giuseppe Ruzzi +1
A universal C*-algebra of gauge invariant operators is presented, describing the electromagnetic field as well as operations creating pairs of static electric charges having opposi…
Aharonov-Bohm superselection sectors
Claudio Dappiaggi, Giuseppe Ruzzi, Ezio Vasselli
We show that the Aharonov-Bohm effect finds a natural description in the setting of QFT on curved spacetimes in terms of superselection sectors of local observables. The extension…
On string-localized potentials and gauge fields
Detlev Buchholz, Fabio Ciolli, Giuseppe Ruzzi +1
A recent idea, put forward by Mund, Rehren and Schroer, is discussed; it suggests that in gauge quantum field theory one can replace the point-localized gauge fields by string-loca…
Background potentials and superselection sectors
Ezio Vasselli
The basic aspects of the Aharonov-Bohm effect can be summarized by the remark that wavefunctions become sections of a line bundle with a flat connection (that is, a "flat potential…
Linking numbers in local quantum field theory
Detlev Buchholz, Fabio Ciolli, Giuseppe Ruzzi +1
Linking numbers appear in local quantum field theory in the presence of tensor fields, which are closed two-forms on Minkowski space. Given any pair of such fields, it is shown tha…
Gerbes over posets and twisted C*-dynamical systems
Ezio Vasselli
A base generating the topology of a space becomes a partially ordered set (poset), when ordered under inclusion of open subsets. Given a precosheaf over of fixed-point…
The universal C*-algebra of the electromagnetic field II. Topological charges and spacelike linear fields
Detlev Buchholz, Fabio Ciolli, Giuseppe Ruzzi +1
Conditions for the appearance of topological charges are studied in the framework of the universal C*-algebra of the electromagnetic field, which is represented in any theory descr…
The universal C*-algebra of the electromagnetic field
Detlev Buchholz, Fabio Ciolli, Giuseppe Ruzzi +1
A universal C*-algebra of the electromagnetic field is constructed. It is represented in any quantum field theory which incorporates electromagnetism and expresses basic features o…
QED Representation for the Net of Causal Loops
Fabio Ciolli, Giuseppe Ruzzi, Ezio Vasselli
The present work tackles the existence of local gauge symmetries in the setting of Algebraic Quantum Field Theory (AQFT). The net of causal loops, previously introduced by the auth…
The C(X)-algebra of a net and index theory
Giuseppe Ruzzi, Ezio Vasselli
Given a connected and locally compact Hausdorff space X with a good base K we assign, in a functorial way, a C(X)-algebra to any precosheaf of C*-algebras A defined over K. Afterwa…
Presheaves of superselection structures in curved spacetimes
Ezio Vasselli
We show that superselection structures on curved spacetimes, that are expected to describe quantum charges affected by the underlying geometry, are categories of sections of preshe…
Presheaves of symmetric tensor categories and nets of C*-algebras
Ezio Vasselli
Motivated by algebraic quantum field theory, we study presheaves of symmetric tensor categories defined over the base of a space, intended as a spacetime. Any section of a presheaf…
Causal posets, loops and the construction of nets of local algebras for QFT
Fabio Ciolli, Giuseppe Ruzzi, Ezio Vasselli
We provide a model independent construction of a net of C*-algebras satisfying the Haag-Kastler axioms over any spacetime manifold. Such a net, called the net of causal loops, is c…
Representations of nets of C*-algebras over S^1
Giuseppe Ruzzi, Ezio Vasselli
In recent times a new kind of representations has been used to describe superselection sectors of the observable net over a curved spacetime, taking into account of the effects of…
A new light on nets of C*-algebras and their representations
Giuseppe Ruzzi, Ezio Vasselli
The present paper deals with the question of representability of nets of C*-algebras whose underlying poset, indexing the net, is not upward directed. A particular class of nets, c…
Bundles of C*-categories, II: C*-dynamical systems and Dixmier-Douady invariants
Ezio Vasselli
We introduce a cohomological invariant arising from a class in nonabelian cohomology. This invariant generalizes the Dixmier-Douady class and encodes the obstruction to a C*-algebr…
Net bundles over posets and K-theory
J. E. Roberts, G. Ruzzi, E. Vasselli
We continue studying net bundles over partially ordered sets (posets), defined as the analogues of ordinary fibre bundles. To this end, we analyze the connection between homotopy,…
Bundles of C*-algebras and the KK(X;-,-)-bifunctor
Ezio Vasselli
An overview about C*-algebra bundles with a Z-grading is presented, with particular emphasis on classification questions. In particular, we discuss the role of the representable KK…
Extension of automorphisms to C*-crossed products with non-trivial centre
Roberto Conti, Ezio Vasselli
Given a quasi-special endomorphism of a C*-algebra A with nontrivial center, we study an extension problem for automorphisms of A to a minimal cross-product B of A by . Expl…