@phdthesis{Schoetz2018, author = {Sch{\"o}tz, Matthias}, title = {Convergent Star Products and Abstract O*-Algebras}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-174355}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2018}, abstract = {Diese Dissertation behandelt ein Problem aus der Deformationsquantisierung: Nachdem man die Quantisierung eines klassischen Systems konstruiert hat, w{\"u}rde man gerne ihre mathematischen Eigenschaften verstehen (sowohl die des klassischen Systems als auch die des Quantensystems). Falls beide Systeme durch *-Algebren {\"u}ber dem K{\"o}rper der komplexen Zahlen beschrieben werden, bedeutet dies dass man die Eigenschaften bestimmter *-Algebren verstehen muss: Welche Darstellungen gibt es? Was sind deren Eigenschaften? Wie k{\"o}nnen die Zust{\"a}nde in diesen Darstellungen beschrieben werden? Wie kann das Spektrum der Observablen beschrieben werden? Um eine hinreichend allgemeine Behandlung dieser Fragen zu erm{\"o}glichen, wird das Konzept von abstrakten O*-Algebren entwickelt. Dies sind im Wesentlichen *-Algebren zusammen mit einem Kegel positiver linearer Funktionale darauf (z.B. die stetigen positiven linearen Funktionale wenn man mit einer *-Algebra startet, die mit einer gutartigen Topologie versehen ist). Im Anschluss daran wird dieser Ansatz dann auf zwei Beispiele aus der Deformationsquantisierung angewandt, die im Detail untersucht werden.}, subject = {Deformationsquantisierung}, language = {en} } @phdthesis{Reichert2017, author = {Reichert, Thorsten}, title = {Classification and Reduction of Equivariant Star Products on Symplectic Manifolds}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-153623}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {This doctoral thesis provides a classification of equivariant star products (star products together with quantum momentum maps) in terms of equivariant de Rham cohomology. This classification result is then used to construct an analogon of the Kirwan map from which one can directly obtain the characteristic class of certain reduced star products on Marsden-Weinstein reduced symplectic manifolds from the equivariant characteristic class of their corresponding unreduced equivariant star product. From the surjectivity of this map one can conclude that every star product on Marsden-Weinstein reduced symplectic manifolds can (up to equivalence) be obtained as a reduced equivariant star product.}, subject = {Homologische Algebra}, language = {en} } @article{SchenkelUhlemann2010, author = {Schenkel, Alexander and Uhlemann, Christoph F.}, title = {Field Theory on Curved Noncommutative Spacetimes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68648}, year = {2010}, abstract = {We study classical scalar field theories on noncommutative curved spacetimes. Following the approach of Wess et al. [Classical Quantum Gravity 22 (2005), 3511 and Classical Quantum Gravity 23 (2006), 1883], we describe noncommutative spacetimes by using (Abelian) Drinfel'd twists and the associated ?-products and ?-differential geometry. In particular, we allow for position dependent noncommutativity and do not restrict ourselves to the Moyal-Weyl deformation. We construct action functionals for real scalar fields on noncommutative curved spacetimes, and derive the corresponding deformed wave equations. We provide explicit examples of deformed Klein-Gordon operators for noncommutative Minkowski, de Sitter, Schwarzschild and Randall-Sundrum spacetimes, which solve the noncommutative Einstein equations. We study the construction of deformed Green's functions and provide a diagrammatic approach for their perturbative calculation. The leading noncommutative corrections to the Green's functions for our examples are derived.}, subject = {Physik}, language = {en} }