1. Origin of Abelian gauge symmetries in heterotic/F-theory dualityMirjam Cvetič, Antonella Grassi, Denis Klevers, Peng Song, Maximilian Poretschkin, 2016, izvirni znanstveni članek Opis: We study aspects of heterotic/F-theory duality for compactifications with Abelian gauge symmetries. We consider F-theory on general Calabi-Yau manifolds with a rank one Mordell-Weil group of rational sections. By rigorously performing the stable degeneration limit in a class of toric models, we derive both the Calabi-Yau geometry as well as the spectral cover describing the vector bundle in the heterotic dual theory. We carefully investigate the spectral cover employing the group law on the elliptic curve in the heterotic theory. We find in explicit examples that there are three different classes of heterotic duals that have U(1) factors in their low energy effective theories: split spectral covers describing bundles with S(U(m) x U(1)) structure group, spectral covers containing torsional sections that seem to give rise to bundles with SU(m) X Z(k) structure group and bundles with purely non-Abelian structure groups having a centralizer in E-8 containing a U(1) factor. In the former two cases, it is required that the elliptic fibration on the heterotic side has a non-trivial Mordell-Weil group. While the number of geometrically massless U(1)'s is determined entirely by geometry on the F-theory side, on the heterotic side the correct number of U(1)'s is found by taking into account a Stiickelberg mechanism in the lower-dimensional effective theory. In geometry, this corresponds to the condition that sections in the two half K3 surfaces that arise in the stable degeneration limit of F-theory can be glued together globally. Ključne besede: F-theory, string duality, superstrings, heterotic strings, M-theory Objavljeno: 27.06.2017; Ogledov: 167; Prenosov: 3 Celotno besedilo (1,15 MB) |
2. Type II string theory on Calabi-Yau manifolds with torsion and non-Abelian discrete gauge symmetriesVolker Braun, Mirjam Cvetič, Ron Donagi, Maximilian Poretschkin, 2017, izvirni znanstveni članek Opis: We provide the first explicit example of Type IIB string theory compactification on a globally defined Calabi-Yau threefold with torsion which results in a four-dimensional effective theory with a non-Abelian discrete gauge symmetry. Our example is based on a particular Calabi-Yau manifold, the quotient of a product of three elliptic curves by a fixed point free action of Z(2) x Z(2). Its cohomology contains torsion classes in various degrees. The main technical novelty is in determining the multiplicative structure of the (torsion part of) the cohomology ring, and in particular showing that the cup product of second cohomology torsion elements goes non-trivially to the fourth cohomology. This specifies a non-Abelian, Heisenberg-type discrete symmetry group of the four-dimensional theory. Ključne besede: string field theory, conformal field models, string theory, discrete symmetries Objavljeno: 08.03.2018; Ogledov: 106; Prenosov: 1 Celotno besedilo (355,78 KB) |
3. Discrete symmetries in Heterotic/F-theory duality and mirror symmetryMirjam Cvetič, Antonella Grassi, Maximilian Poretschkin, 2017, izvirni znanstveni članek Opis: We study aspects of Heterotic/F-theory duality for compactifications with Abelian discrete gauge symmetries. We consider F-theory compactifications on genus-one fibered Calabi-Yau manifolds with n-sections, associated with the Tate-Shafarevich group Z(n). Such models are obtained by studying first a specific toric set-up whose associated Heterotic vector bundle has structure group Z(n). By employing a conjectured Heterotic/F-theory mirror symmetry we construct dual geometries of these original toric models, where in the stable degeneration limit we obtain a discrete gauge symmetry of order two and three, for compactifications to six dimensions. We provide explicit constructions of mirror-pairs for symmetric examples with Z(2) and Z(3), in six dimensions. The Heterotic models with symmetric discrete symmetries are related in field theory to a Higgsing of Heterotic models with two symmetric abelian U(1) gauge factors, where due to the Stuckelberg mechanism only a diagonal U(1) factor remains massless, and thus after Higgsing only a diagonal discrete symmetry of order n is present in the Heterotic models and detected via Heterotic/F-theory duality. These constructions also provide further evidence for the conjectured mirror symmetry in Heterotic/F-theory at the level of fibrations with torsional sections and those with multi-sections. Ključne besede: discrete symmetries, F-theory, string duality, superstrings, heterotic strings Objavljeno: 08.03.2018; Ogledov: 90; Prenosov: 2 Celotno besedilo (510,30 KB) |