Emergent Strings, Duality and Weak Coupling Limits for Two-Form Fields

We systematically analyse weak coupling limits for 2-form tensor fields in the presence of gravity. Such limits are significant for testing various versions of the Weak Gravity and Swampland Distance Conjectures, and more broadly, the phenomenon of emergence. The weak coupling limits for 2-forms correspond to certain infinite-distance limits in the moduli space of string compactifications, where asymptotically tensionless, solitonic strings arise. These strings are identified as weakly coupled fundamental strings in a dual frame, which makes the idea of emergence manifest. Concretely we first consider weakly coupled tensor fields in six-dimensional compactifications of F-theory, where the arising tensionless strings play the role of dual weakly coupled heterotic strings. As the main part of this work, we consider certain infinite distance limits of Type IIB strings on K3 surfaces, for which we show that the asymptotically tensionless strings describe dual fundamental Type IIB strings, again on K3 surfaces. By contrast the analogous weak coupling limits of M-theory compactifications are found to correspond to an F-theory limit where an extra dimension emerges rather than tensionless strings. We comment on extensions of our findings to four-dimensional compactifications.Comment: 30 pages, 1 figure; v2: cosmetic changes and minor comments adde

Modular Fluxes, Elliptic Genera, and Weak Gravity Conjectures in Four Dimensions

We analyse the Weak Gravity Conjecture for chiral four-dimensional F-theory compactifications with N=1 supersymmetry. Extending our previous work on nearly tensionless heterotic strings in six dimensions, we show that under certain assumptions a tower of asymptotically massless states arises in the limit of vanishing coupling of a U(1) gauge symmetry coupled to gravity. This tower contains super-extremal states whose charge-to-mass ratios are larger than those of certain extremal dilatonic Reissner-Nordstrom black holes, precisely as required by the Weak Gravity Conjecture. Unlike in six dimensions, the tower of super-extremal states does not always populate a charge sub-lattice. The main tool for our analysis is the elliptic genus of the emergent heterotic string in the chiral N=1 supersymmetric effective theories. This also governs situations where the heterotic string is non-perturbative. We show how it can be computed in terms of BPS invariants on elliptic four-folds, by making use of various dualities and mirror symmetry. Compared to six dimensions, the geometry of the relevant elliptically fibered four-folds is substantially richer than that of the three-folds, and we classify the possibilities for obtaining critical, nearly tensionless heterotic strings. We find that the (quasi-)modular properties of the elliptic genus crucially depend on the choice of flux background. Our general results are illustrated in a detailed example.Comment: 72 pages, 2 figure

A Stringy Test of the Scalar Weak Gravity Conjecture

We prove a version of the Weak Gravity Conjecture for 6d F-theory or heterotic string compactifications with 8 supercharges. This sharpens our previous analysis by including massless scalar fields. The latter are known to modify the Weak Gravity Conjecture bound in two a priori independent ways: First, the extremality condition of a charged black hole is modified, and second, the test particles required to satisfy the Weak Gravity Conjecture are subject to additional Yukawa type interactions. We argue on general grounds that at weak coupling, the two types of effects are equivalent for a tower of asymptotically massless charged test particles predicted by the Swampland Distance Conjecture. We then specialise to F-theory compactified on elliptic Calabi-Yau three-folds and prove that the precise numerical bound on the charge-to-mass ratio is satisfied at weak coupling. This amounts to an intriguing coincidence of two a priori different notions of extremality, namely one based on the balance of gauge, gravitational and scalar forces for extremal (non-BPS) black holes, and the other encoded in the modular properties of certain Jacobi forms. In the presence of multiple abelian gauge group factors, the elliptic genus counting these states is a lattice quasi-Jacobi form of higher rank, and we exemplify this in a model with two abelian gauge group factors.Comment: 31 pages, 2 figure

Die DGSv in ihren (historischen) Spannungsfeldern

Der Autor beschreibt zehn wichtige Spannungsfelder, die er während seiner langjährigen Tätigkeit als Vorsitzender der DGSv wahrgenommen hat und benennt auf dem Hintergrund dieser Erfahrungen und seiner Wahrnehmung der aktuellen Verbandspolitik bedeutsame Themen für den Professionalisierungsprozess in der Zukunft

Fallverstehen in der Supervision

Es geht um Verstehen: eine unabdingbare Voraussetzung in jedem kommunikativen Handeln. Deshalb schränken wir den Begriff nun ein, um ihn professionsspezifisch zu qualifizieren. Wir blicken nicht auf das Alltagsverstehen, was nicht heißt, dass nicht auch dieses Verstehen kompliziert sein kann. Wir meinen auch nicht das empathische Verstehen im Sinne von Mitfühlen und Teilhabe an der Existenz des Anderen, sondern eben das Fallverstehen, also die Durchdringung einer meist sehr komplexen und kontingenten Situation oder Szene in ihrer unterschiedlichen Dimensionalität, d.h. in ihren normativen, sozialen, psychischen, ökonomischen, strukturellen, historischen, politischen, kulturellen  und auch in ihren bewussten und unbewussten Wirklichkeiten mit dem Ziel zu einem vertieften Verständnis der Situation, dem Sinn zu kommen, die Handeln wieder möglich macht

Beitrag der Zeitschriften zur Professionalisierung von Supervision - Felderkundungen

Die Supervision und die Supervisoren, die in den 1 980er Jahren begannen, ihr Ursprungsland, die Sozialarbeit, zu verlassen und sich vorsichtig in neue Felder zu begeben, waren darauf angewiesen, diese neuen Felder kennen zu lernen und zu verstehen; sie mussten ihre Beratungsarbeit diesen Feldern anpassen, nicht unkritisch, aber eben doch mit anderen Perspektiven und Interventionen

Holomorphic Anomalies, Fourfolds and Fluxes

We investigate holomorphic anomalies of partition functions underlying string compactifications on Calabi-Yau fourfolds with background fluxes. For elliptic fourfolds the partition functions have an alternative interpretation as elliptic genera of N=1 supersymmetric string theories in four dimensions, or as generating functions for relative Gromov-Witten invariants of fourfolds with fluxes. We derive the holomorphic anomaly equations by starting from the BCOV formalism of topological strings, and translating them into geometrical terms. The result can be recast into modular and elliptic anomaly equations. As a new feature, as compared to threefolds, we find an extra contribution which is given by a gravitational descendant invariant. This leads to linear terms in the anomaly equations, which support an algebra of derivatives mapping between partition functions of the various flux sectors. These geometric features are mirrored by certain properties of quasi-Jacobi forms. We also offer an interpretation of the physics from the viewpoint of the worldsheet theory.Comment: 64 pages, 4 figure

Wege zur Professionalisierung - Über die Anfänge der Supervision in Deutschland

FoRUM SuPERVISION: Wir freuen uns darüber, hier mit zwei Menschen zusammen zu kommen, die von der Supervision biografisch geprägt sind und die die Profession Supervision in den letzten Jahrzehnten nachhaltig geprägt haben. Wir würden gern von Ihnen etwas mehr erfahren, wie Sie die Anfänge der Supervision in Deutschland erlebt haben. Dabei geht es uns weniger um eine exakte Rekonstruktion Geschichte der Supervision - das sollten wir vielleicht späteren Generationen vorbehalten - als vielmehr um prägende biografische Begegnungen und wichtige Entwicklungspunkte

Novel Homoleptic and Heteroleptic Pt(II) β‐oxodithiocinnamic ester Complexes: Synthesis, Characterization, Interactions with 9‐methylguanine and Antiproliferative Activity

Abstract Three new series of homoleptic and heteroleptic platinum(II) β‐oxodithiocinnamic ester complexes, [Pt(L1–L9) 2 ], [Pt(L1–L9)(DMS)Cl] and [Pt(L1–L9)(DMSO)Cl], were synthesized and characterized using elemental analysis, mass spectrometry, and different NMR spectroscopy ( 1 H, 13 C{ 1 H} and 195 Pt). The β‐oxodithiocinnamic esters coordinate towards the platinum(II) centre as O,S‐bidentate chelating ligands. The structures of HL3, [Pt(L2) 2 ], [Pt(L6)(DMS)Cl] as well as [Pt(L2)(DMSO)Cl] have been confirmed through the X‐ray crystallography, where the platinum(II) complexes exhibit a slightly distorted square planar geometry. In this article, we also investigated the solvolysis of three representative Pt(II) complexes, as well as the interaction with 9‐methylguanine as a DNA model system, by utilizing the LC‐ESI‐MS technique. A selection of the complexes was assessed for their use as anticancer agents, and cytotoxicity assays with these complexes showed modest toxicity on both Cisplatin sensitive and resistant ovarian cancer cell lines. However, the compounds cytotoxicity was not affected by the Cisplatin resistance mechanisms and a specific selection of the ligands may modify the cell line specificity.imag