Self-Dual Tensors and Partial Supersymmetry Breaking in Five Dimensions

We study spontaneous supersymmetry breaking of five-dimensional supergravity theories from sixteen to eight supercharges in Minkowski vacua. This N=4 to N=2 breaking is induced by Abelian gaugings that require the introduction of self-dual tensor fields accompanying the vectors in the gravity multiplet and vector multiplets. These tensor fields have first-order kinetic terms and can become massive by a Stueckelberg-like mechanism. We identify the general class of N=2 vacua and show how the N=4 spectrum splits into massless and massive N=2 multiplets. In particular, we find a massive gravitino multiplet, containing two complex massive tensors, and a number of massive tensor multiplets and hypermultiplets. We determine the resulting N=2 effective action for the massless multiplets obtained by integrating out massive fields. We show that the metric and Chern-Simons terms of the vectors are corrected at one-loop by massive tensors as well as spin-1/2 and spin-3/2 fermions. These contributions are independent of the supersymmetry-breaking scale and thus have to be included at arbitrarily low energies.Comment: 33 page

The Arithmetic of Elliptic Fibrations in Gauge Theories on a Circle

The geometry of elliptic fibrations translates to the physics of gauge theories in F-theory. We systematically develop the dictionary between arithmetic structures on elliptic curves as well as desingularized elliptic fibrations and symmetries of gauge theories on a circle. We show that the Mordell-Weil group law matches integral large gauge transformations around the circle in Abelian gauge theories and explain the significance of Mordell-Weil torsion in this context. We also use Higgs transitions and circle large gauge transformations to introduce a group law for genus-one fibrations with multi-sections. Finally, we introduce a novel arithmetic structure on elliptic fibrations with non-Abelian gauge groups in F-theory. It is defined on the set of exceptional divisors resolving the singularities and divisor classes of sections of the fibration. This group structure can be matched with certain integral non-Abelian large gauge transformations around the circle when studying the theory on the lower-dimensional Coulomb branch. Its existence is required by consistency with Higgs transitions from the non-Abelian theory to its Abelian phases in which it becomes the Mordell-Weil group. This hints towards the existence of a new underlying geometric symmetry.Comment: 43 pages, 3 figure

Partial Supergravity Breaking and the Effective Action of Consistent Truncations

We study vacua of N = 4 half-maximal gauged supergravity in five dimensions and determine crucial properties of the effective theory around the vacuum. The main focus is on configurations with exactly two broken supersymmetries, since they frequently appear in consistent truncations of string theory and supergravity. Evaluating one-loop corrections to the Chern-Simons terms we find necessary conditions to ensure that a consistent truncation also gives rise to a proper effective action of an underlying more fundamental theory. To obtain concrete examples, we determine the N=4 action of M-theory on six-dimensional SU(2)-structure manifolds with background fluxes. Calabi-Yau threefolds with vanishing Euler number are examples of SU(2)-structure manifolds that yield N=2 Minkowski vacua. We find that that one-loop corrections to the Chern-Simons terms vanish trivially and thus do not impose constraints on identifying effective theories. This result is traced back to the absence of isometries on these geometries. Examples with isometries arise from type IIB supergravity on squashed Sasaki-Einstein manifolds. In this case the one-loop gauge Chern-Simons terms vanish due to non-trivial cancellations, while the one-loop gravitational Chern-Simons terms are non-zero.Comment: 44 pages, v2: minor changes, references adde

Entwicklung stationärer Phasen für die Ionenchromatographie zur Trennung von Kohlenhydraten

Diese Arbeit umfasst die Herstellung und Charakterisierung von neuen stationären Phasen zur Trennung von Kohlenhydraten mittels Anionenchromatographie und elektrochemischer Detektion. Auf hochquervernetzten PS-DVB-Harzen konnten durch Chloromethylierung, Beschichtung und pfropfpolymerisation unterschiedliche Typen von Oberflächenmodifizierungen durchgeführt werden, die zu präfunktionalisierten Trägermaterialien führten. Die anschließende Funktionalisierung mit verschiedenen Aminen und Diaminen führte zu stabilen Anionenaustauschern hoher Kapazität und Trennleistung und konnten erfolgreich zur Trennung von Kohlenhydraten eingesetzt werden. Auf dem Gebiet der agglomerierten Ionenaustauscher wurde das bewährte Konzept der Latexaustauscher weiterentwickelt und durch die Immobilisierung von polykationischen Ketten in Form von Ionenen erweitert. Die Struktur der Ionene ist durch eine Vielzahl an verfügbarenMonomeren sehr variabel und die erhaltenen Ionenaustauscher zur Trennung von Kohlenhydraten geeignet. Trends und Trenneigenschaften aller hergestellten Phasen wurden untersucht und unter dem Aspekt der Eignung zur Trennung von Kohlenhydraten untereinander verglichen

Optimal non-circular fiber geometries for image scrambling in high-resolution spectrographs

Optical fibers are a key component for high-resolution spectrographs to attain high precision in radial velocity measurements. We present a custom fiber with a novel core geometry - a 'D'-shape. From a theoretical standpoint, such a fiber should provide superior scrambling and modal noise mitigation, since unlike the commonly used circular and polygonal fiber cross sections, it shows chaotic scrambling. We report on the fabrication process of a test fiber and compare the optical properties, scrambling performance, and modal noise behavior of the D-fiber with those of common polygonal fibers.Comment: 7 pages, 6 figures, submitted to SPIE Astronomical Telescopes & Instrumentation 2016 (9912-192