Superstring BRST Cohomology

We first derive all world-sheet action functionals for NSR superstring models with (1,1) supersymmetry and any number of abelian gauge fields, for gauge transformations of the standard form. Then we prove for these models that the BRST cohomology groups $H^g(s)$, $g<4$ (with the antifields taken into account) are isomorphic to those of the corresponding bosonic string models, whose cohomology is fully known. This implies that the nontrivial global symmetries, Noether currents, background charges, consistent deformations and candidate gauge anomalies of an NSR (1,1) superstring model are in one-to-one correspondence with their bosonic counterparts.Comment: LaTeX2e, 44 pages, minor correction

NS Fivebrane and Tachyon Condensation

We argue that a semi-infinite D6-brane ending on an NS5-brane can be obtained from the condensation of the tachyon on the unstable D9-brane of type IIA theory. The construction uses a combination of the descriptions of these branes as solitons of the worldvolume theory of the D9-brane. The NS5-brane, in particular, involves a gauge bundle which is operator valued, and hence is better thought of as a gerbe.Comment: 20 pages, harvma

Toric Construction of Global F-Theory GUTs

We systematically construct a large number of compact Calabi-Yau fourfolds which are suitable for F-theory model building. These elliptically fibered Calabi-Yaus are complete intersections of two hypersurfaces in a six dimensional ambient space. We first construct three-dimensional base manifolds that are hypersurfaces in a toric ambient space. We search for divisors which can support an F-theory GUT. The fourfolds are obtained as elliptic fibrations over these base manifolds. We find that elementary conditions which are motivated by F-theory GUTs lead to strong constraints on the geometry, which significantly reduce the number of suitable models. The complete database of models is available at http://hep.itp.tuwien.ac.at/f-theory/. We work out several examples in more detail.Comment: 35 pages, references adde

(0,2) Deformations of Linear Sigma Models

We study (0,2) deformations of a (2,2) supersymmetric gauged linear sigma model for a Calabi-Yau hypersurface in a Fano toric variety. In the non-linear sigma model these correspond to some of the holomorphic deformations of the tangent bundle on the hypersurface. Combinatorial formulas are given for the number of these deformations, and we show that these numbers are exchanged by mirror symmetry in a subclass of the models.Comment: 35 pages; uses xy-fig; typos fixed, acknowledgments adde

Four-modulus "Swiss Cheese" chiral models

We study the 'Large Volume Scenario' on explicit, new, compact, four-modulus Calabi-Yau manifolds. We pay special attention to the chirality problem pointed out by Blumenhagen, Moster and Plauschinn. Namely, we thoroughly analyze the possibility of generating neutral, non-perturbative superpotentials from Euclidean D3-branes in the presence of chirally intersecting D7-branes. We find that taking proper account of the Freed-Witten anomaly on non-spin cycles and of the Kaehler cone conditions imposes severe constraints on the models. Nevertheless, we are able to create setups where the constraints are solved, and up to three moduli are stabilized.Comment: 40 pages, 10 figures, clarifying comments added, minor mistakes correcte

Heterotic Bundles on Calabi-Yau Manifolds with Small Picard Number

We undertake a systematic scan of vector bundles over spaces from the largest database of known Calabi-Yau three-folds, in the context of heterotic string compactification. Specifically, we construct positive rank five monad bundles over Calabi-Yau hypersurfaces in toric varieties, with the number of Kahler moduli equal to one, two, and three and extract physically interesting models. We select models which can lead to three families of matter after dividing by a freely-acting discrete symmetry and including Wilson lines. About 2000 such models on two manifolds are found.Comment: 26 pages, 1 figur

Topological String Amplitudes, Complete Intersection Calabi-Yau Spaces and Threshold Corrections

We present the most complete list of mirror pairs of Calabi-Yau complete intersections in toric ambient varieties and develop the methods to solve the topological string and to calculate higher genus amplitudes on these compact Calabi-Yau spaces. These symplectic invariants are used to remove redundancies in examples. The construction of the B-model propagators leads to compatibility conditions, which constrain multi-parameter mirror maps. For K3 fibered Calabi-Yau spaces without reducible fibers we find closed formulas for all genus contributions in the fiber direction from the geometry of the fibration. If the heterotic dual to this geometry is known, the higher genus invariants can be identified with the degeneracies of BPS states contributing to gravitational threshold corrections and all genus checks on string duality in the perturbative regime are accomplished. We find, however, that the BPS degeneracies do not uniquely fix the non-perturbative completion of the heterotic string. For these geometries we can write the topological partition function in terms of the Donaldson-Thomas invariants and we perform a non-trivial check of S-duality in topological strings. We further investigate transitions via collapsing D5 del Pezzo surfaces and the occurrence of free Z2 quotients that lead to a new class of heterotic duals.Comment: 117 pages, 1 Postscript figur

Insomnia in patients with chronic tinnitus: Cognitive and emotional distress as moderator variables

Introduction: Tinnitus is often associated with disturbed sleep, but there are also patients without sleep problems. The mechanisms for developing insomnia or not in tinnitus patients are still unknown. The aim of the present study was to extract possible tinnitus specific factors that increase the risk of developing insomnia based on the analysis of a large patient cohort suffering from chronic tinnitus. Method: 173 patients presenting at the multidisciplinary tinnitus center of a University Hospital completed a questionnaire measuring specific psychological symptoms of insomnia (RIS) and a tinnitus questionnaire (TQ). The scores of all ten RIS items were compared between tinnitus patients and 94 healthy individuals by separate ANOVAs in order to specify the extent of insomnia specific symptoms in the tinnitus group. In a second step a multiple linear regression analysis was performed in the tinnitus sample with subscales of the TQ (excluding the TQsleep scale), age and duration of tinnitus as independent variables and the RIS score as the dependent variables. Results: Tinnitus patients differed from healthy controls not only in impaired sleep quality but also in insomnia specific concerns and anxiety. Tinnitus related emotional and cognitive distress and somatic complaints correlated with severity of insomnia, whereas no association of age or duration of tinnitus with severity of insomnia was found. Conclusion: Our results suggest that chronic tinnitus patients have more sleeping difficulties and associated worries about sleep or negative emotions in contrast to healthy controls. Tinnitus-related distress is related to insomnia (C) 2016 Published by Elsevier Inc

Psychophysiological associations between chronic tinnitus and sleep: a cross validation of tinnitus and insomnia questionnaires

Background.The aim of the present study was to assess the prevalence of insomnia in chronic tinnitus and the association of tinnitus distress and sleep disturbance. Methods.We retrospectively analysed data of 182 patients with chronic tinnitus who completed the Tinnitus Questionnaire (TQ) and the Regensburg Insomnia Scale (RIS). Descriptive comparisons with the validation sample of the RIS including exclusively patients with primary/psychophysiological insomnia, correlation analyses of the RIS with TQ scales, and principal component analyses (PCA) in the tinnitus sample were performed. TQ total score was corrected for the TQ sleep items. Results. Prevalence of insomnia was high in tinnitus patients (76%) and tinnitus distress correlated with sleep disturbance