Computational Tools for Cohomology of Toric Varieties

In this review, novel non-standard techniques for the computation of cohomology classes on toric varieties are summarized. After an introduction of the basic definitions and properties of toric geometry, we discuss a specific computational algorithm for the determination of the dimension of line-bundle valued cohomology groups on toric varieties. Applications to the computation of chiral massless matter spectra in string compactifications are discussed and, using the software package cohomCalg, its utility is highlighted on a new target space dual pair of (0,2) heterotic string models.Comment: 17 pages, 4 tables; prepared for the special issue "Computational Algebraic Geometry in String and Gauge Theory" of Advances in High Energy Physics, cohomCalg implementation available at http://wwwth.mppmu.mpg.de/members/blumenha/cohomcalg

Canola stand establishment in 2011

Non-Peer Reviewe

Cohomology of Line Bundles: A Computational Algorithm

We present an algorithm for computing line bundle valued cohomology classes over toric varieties. This is the basic starting point for computing massless modes in both heterotic and Type IIB/F-theory compactifications, where the manifolds of interest are complete intersections of hypersurfaces in toric varieties supporting additional vector bundles.Comment: 11 pages, 1 figure, 2 tables; v2: typos and references corrected; v3: proof-related statements updated, cohomCalg implementation available at http://wwwth.mppmu.mpg.de/members/blumenha/cohomcalg

Global existence and future asymptotic behaviour for solutions of the Einstein-Vlasov-scalar field system with surface symmetry

We prove in the cases of plane and hyperbolic symmetries a global in time existence result in the future for comological solutions of the Einstein-Vlasov-scalar field system, with the sources generated by a distribution function and a scalar field, subject to the Vlasov and wave equations respectively. The spacetime is future geodesically complete in the special case of plane symmetry with only a scalar field. Causal geodesics are also shown to be future complete for homogeneous solutions of the Einstein-Vlasov-scalar field system with plane and hyperbolic symmetry.Comment: 14 page

On free nets over Minkowski space

27 pages, no figures.-- MSC2000 codes: 46L60, 81T05.MR#: MR1369988 (96m:81132)Zbl#: Zbl 0883.46040Using standard results on CAR- and CCR-theory and on representation theory of the Poincaré group a direct way to construct nets of local C*-algebras satisfying Haag-Kastler's axioms is given. No explicite use of any field operator or of any concrete representation of the algebra is made. The nets are associated to models of mass m ≥ 0 and arbitrary spin or helicity. Finally, Fock states satisfying the spectrality condition are specified.First author (H.B.) was partly supported by DFG; SFB 288: “Differentialgeometrie und Quantenphysik”. Second author (M.J.) was supported by DFG; SFB 288: “Differentialgeometrie und Quantenphysik”. Third author (F. Ll.) was supported by a grant of the Spanish Ministry of Education/CICYT.Publicad