459 research outputs found

    Asymptotic degeneracy of dyonic N=4 string states and black hole entropy

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    It is shown that the asymptotic growth of the microscopic degeneracy of BPS dyons in four-dimensional N=4 string theory captures the known corrections to the macroscopic entropy of four-dimensional extremal black holes. These corrections are subleading in the limit of large charges and originate both from the presence of interactions in the effective action quadratic in the Riemann tensor and from non-holomorphic terms. The presence of the non-holomorphic corrections and their contribution to the thermodynamic free energy is discussed. It is pointed out that the expression for the microscopic entropy, written as a function of the dilaton field, is stationary at the horizon by virtue of the attractor equations.Comment: 16 pages Late

    Perturbative gravitational couplings and Siegel modular forms in D=4,N=2D=4,N=2 string models

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    We consider four-parameter D=4,N=2D=4,N=2 string models with Hodge numbers (4,214−12n)(4,214- 12n) and (4,148)(4,148), and we express their perturbative Wilsonian gravitational coupling F1F_1 in terms of Siegel modular forms.Comment: 8 pages, Latex 2.09, Contribution to the Proceedings of the 30th International Symposium Ahrenshoop on the Theory of Elementary Particles, Buckow, August 27-31, 199

    Holographic Gravitational Anomalies

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    In the AdS/CFT correspondence one encounters theories that are not invariant under diffeomorphisms. In the boundary theory this is a gravitational anomaly, and can arise in 4k+2 dimensions. In the bulk, there can be gravitational Chern-Simons terms which vary by a total derivative. We work out the holographic stress tensor for such theories, and demonstrate agreement between the bulk and boundary. Anomalies lead to novel effects, such as a nonzero angular momentum for global AdS(3). In string theory such Chern-Simons terms are known with exact coefficients. The resulting anomalies, combined with symmetries, imply corrections to the Bekenstein-Hawking entropy of black holes that agree exactly with the microscopic counting.Comment: 25 page

    Polyploid plants have faster rates of multivariate niche differentiation than their diploid relatives

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    Polyploid speciation entails substantial and rapid postzygotic reproductive isolation of nascent species that are initially sympatric with one or both parents. Despite strong postzygotic isolation, ecological niche differentiation has long been thought to be important for polyploid success. Using biogeographic data from across vascular plants, we tested whether the climatic niches of polyploid species are more differentiated than their diploid relatives and if the climatic niches of polyploid species differentiated faster than those of related diploids. We found that polyploids are often more climatically differentiated from their diploid parents than the diploids are from each other. Consistent with this pattern, we estimated that polyploid species generally have higher rates of multivariate niche differentiation than their diploid relatives. In contrast to recent analyses, our results confirm that ecological niche differentiation is an important component of polyploid speciation and that niche differentiation is often significantly faster in polyploids.Polyploid speciation entails substantial and rapid postzygotic reproductive isolation of nascent species that are initially sympatric with one or both parents. Despite strong postzygotic isolation, ecological niche differentiation has long been thought to be important for polyploid success. Using biogeographic data from across vascular plants, we tested whether the climatic niches of polyploid species are more differentiated than their diploid relatives and if the climatic niches of polyploid species differentiated faster than those of related diploids.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/1/ele13402-sup-0001-TableS1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/2/ele13402_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/3/ele13402-sup-0007-TableS7.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/4/ele13402-sup-0003-TableS3.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/5/ele13402-sup-0005-TableS5.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/6/ele13402.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/7/ele13402-sup-0006-TableS6.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/8/ele13402-sup-0002-TableS2.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153074/9/ele13402-sup-0004-TableS4.pd

    Leptogenesis through direct inflaton decay to light particles

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    We present a scenario of nonthermal leptogenesis following supersymmetric hybrid inflation, in the case where inflaton decay to both heavy right handed neutrino and SU(2)_L triplet superfields is kinematically disallowed. Lepton asymmetry is generated through the decay of the inflaton into light particles by the interference of one-loop diagrams with right handed neutrino and SU(2)_L triplet exchange respectively. We require superpotential couplings explicitly violating a U(1) R-symmetry and R-parity. However, the broken R-parity need not have currently observable low-energy signatures. Also, the lightest sparticle can be stable. Some R-parity violating slepton decays may, though, be detectable in the future colliders. We take into account the constraints from neutrino masses and mixing and the preservation of the primordial lepton asymmetry.Comment: 11 pages including 3 figures, uses Revtex, minor corrections, references adde

    Are Labour Markets Necessarily Local? Spatiality, Segmentation and Scale

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    This paper draws on recent debates about scale to approach the geography of labour markets from a dynamic perspective sensitive to the spatiality and scale of labour market restructuring. Its exploration of labour market reconfigurations after the collapse of a major firm (Ansett Airlines) raises questions about geography’s faith in the inherently ‘local’ constitution of labour markets. Through an examination of the job reallocation process after redundancy, the paper suggests that multiple labour markets use and articulate scale in different ways. It argues that labour market rescaling processes are enacted at the critical moment of recruitment, where social networks, personal aspirations and employer preferences combine to shape workers’ destinations

    The spinorial geometry of supersymmetric heterotic string backgrounds

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    We determine the geometry of supersymmetric heterotic string backgrounds for which all parallel spinors with respect to the connection ∇^\hat\nabla with torsion HH, the NS⊗\otimesNS three-form field strength, are Killing. We find that there are two classes of such backgrounds, the null and the timelike. The Killing spinors of the null backgrounds have stability subgroups K\ltimes\bR^8 in Spin(9,1)Spin(9,1), for K=Spin(7)K=Spin(7), SU(4), Sp(2)Sp(2), SU(2)×SU(2)SU(2)\times SU(2) and {1}\{1\}, and the Killing spinors of the timelike backgrounds have stability subgroups G2G_2, SU(3), SU(2) and {1}\{1\}. The former admit a single null ∇^\hat\nabla-parallel vector field while the latter admit a timelike and two, three, five and nine spacelike ∇^\hat\nabla-parallel vector fields, respectively. The spacetime of the null backgrounds is a Lorentzian two-parameter family of Riemannian manifolds BB with skew-symmetric torsion. If the rotation of the null vector field vanishes, the holonomy of the connection with torsion of BB is contained in KK. The spacetime of time-like backgrounds is a principal bundle PP with fibre a Lorentzian Lie group and base space a suitable Riemannian manifold with skew-symmetric torsion. The principal bundle is equipped with a connection λ\lambda which determines the non-horizontal part of the spacetime metric and of HH. The curvature of λ\lambda takes values in an appropriate Lie algebra constructed from that of KK. In addition dHdH has only horizontal components and contains the Pontrjagin class of PP. We have computed in all cases the Killing spinor bilinears, expressed the fluxes in terms of the geometry and determine the field equations that are implied by the Killing spinor equations.Comment: 73pp. v2: minor change

    An Exploratory Analysis of the “Was It Worth It?” Questionnaire as a Novel Metric to Capture Patient Perceptions of Cancer Treatment

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    Objectives: Asking “Was it worth it?” (WIWI) potentially captures the patient perception of a treatment's benefit weighed against its harms. This exploratory analysis evaluates the WIWI questionnaire as a metric of patients’ perspectives on the worthwhileness of cancer treatment. Methods: A 3-item WIWI questionnaire was assessed at end of treatment in patients with cancer on the COMET-2 trial (NCT01522443). WIWI items were evaluated to determine their association with quality of life (QOL), treatment duration, end-of-treatment reason, patient-reported adverse events (AEs), and disease response. Results: A total of 65 patients completed the questionnaire; 40 (62%), 16 (25%), and 9 (14%) patients replied yes, uncertain, and no to “Was it worthwhile for you to receive the cancer treatment given in this study?” (item 1), respectively; 39 (60%), 12 (18%), and 14 (22%) to “If you had to do it over again, would you choose to have this cancer treatment?”; and 40 (62%), 14 (22%), and 11 (17%) to “Would you recommend this cancer treatment to others?” Patients responding yes to item 1 remained on treatment longer than those responding uncertain or no (mean 23.0 vs 11.3 weeks, P<.001). Patients responding uncertain/no to item 1 discontinued treatment because of AEs more frequently than those responding yes (36% vs 7.5%, P=.004) and demonstrated meaningful decline in QOL from baseline (−2.5 vs −0.2 mean change, P<.001). Associations between WIWI responses and most patient-reported AEs or treatment efficacy did not reach statistical significance. Conclusions: Patients who responded affirmatively on WIWI items remained on therapy longer, were less likely to stop treatment because of AEs, and demonstrated superior QOL. The WIWI may inform clinical practice, oncology research, and value frameworks

    Resonant leptogenesis in a predictive SO(10) grand unified model

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    An SO(10) grand unified model considered previously by the authors featuring lopsided down quark and charged lepton mass matrices is successfully predictive and requires that the lightest two right-handed Majorana neutrinons be nearly degenerate in order to obtain the LMA solar neutrino solution. Here we use this model to test its predictions for baryogenesis through resonant-enhanced leptogenesis. With the conventional type I seesaw mechanism, the best predictions for baryogenesis appear to fall a factor of three short of the observed value. However, with a proposed type III seesaw mechanism leading to three pairs of massive pseudo-Dirac neutrinos, resonant leptogenesis is decoupled from the neutrino mass and mixing issues with successful baryogenesis easily obtained.Comment: 22 pages including 1 figure; published version with reference adde

    Leptogenesis and neutrino parameters

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    We calculate the baryonic asymmetry of the universe in the baryogenesis-via-leptogenesis framework, assuming first a quark-lepton symmetry and then a charged-neutral lepton symmetry. We match the results with the experimentally favoured range. In the first case all the oscillation solutions to the solar neutrino problem, except the large mixing matter solution, can lead to the allowed range, but with fine tuning of the parameters. In the second case the general result is quite similar. Some related theoretical hints are discussed.Comment: RevTex, 21 pages with 8 figure
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