861 research outputs found

    Root systems from Toric Calabi-Yau Geometry. Towards new algebraic structures and symmetries in physics?

    Full text link
    The algebraic approach to the construction of the reflexive polyhedra that yield Calabi-Yau spaces in three or more complex dimensions with K3 fibres reveals graphs that include and generalize the Dynkin diagrams associated with gauge symmetries. In this work we continue to study the structure of graphs obtained from CY3CY_3 reflexive polyhedra. We show how some particularly defined integral matrices can be assigned to these diagrams. This family of matrices and its associated graphs may be obtained by relaxing the restrictions on the individual entries of the generalized Cartan matrices associated with the Dynkin diagrams that characterize Cartan-Lie and affine Kac-Moody algebras. These graphs keep however the affine structure, as it was in Kac-Moody Dynkin diagrams. We presented a possible root structure for some simple cases. We conjecture that these generalized graphs and associated link matrices may characterize generalizations of these algebras.Comment: 24 pages, 6 figure

    The Classification of the Simply Laced Berger Graphs from Calabi-Yau CY3CY_3 spaces

    Full text link
    The algebraic approach to the construction of the reflexive polyhedra that yield Calabi-Yau spaces in three or more complex dimensions with K3 fibres reveals graphs that include and generalize the Dynkin diagrams associated with gauge symmetries. In this work we continue to study the structure of graphs obtained from CY3CY_3 reflexive polyhedra. The objective is to describe the ``simply laced'' cases, those graphs obtained from three dimensional spaces with K3 fibers which lead to symmetric matrices. We study both the affine and, derived from them, non-affine cases. We present root and weight structurea for them. We study in particular those graphs leading to generalizations of the exceptional simply laced cases E6,7,8E_{6,7,8} and E6,7,8(1)E_{6,7,8}^{(1)}. We show how these integral matrices can be assigned: they may be obtained by relaxing the restrictions on the individual entries of the generalized Cartan matrices associated with the Dynkin diagrams that characterize Cartan-Lie and affine Kac-Moody algebras. These graphs keep, however, the affine structure present in Kac-Moody Dynkin diagrams. We conjecture that these generalized simply laced graphs and associated link matrices may characterize generalizations of Cartan-Lie and affine Kac-Moody algebras

    KamLAND Bounds on Solar Antineutrinos and neutrino transition magnetic moments

    Get PDF
    We investigate the possibility of detecting solar electron antineutrinos with the KamLAND experiment. These electron antineutrinos are predicted by spin-flavor oscillations at a significant rate even if this mechanism is not the leading solution to the SNP. KamLAND is sensitive to antineutrinos originated from solar 8{}^8B neutrinos. From KamLAND negative results after 145 days of data taking, we obtain model independent limits on the total flux of solar electron antineutrinos $\Phi({}^8 B)< 1.1-3.5\times 10^4 cm^{-2}\ s^{-1},morethanoneorderofmagnitudesmallerthanexistinglimits,andontheirappearanceprobability, more than one order of magnitude smaller than existing limits, and on their appearance probability P<0.15%(95antineutrinoproductionbyspinflavorprecession,thisupperboundimpliesanupperlimitontheproductoftheintrinsicneutrinomagneticmomentandthevalueofthesolarmagneticfield (95% CL). Assuming a concrete model for antineutrino production by spin-flavor precession, this upper bound implies an upper limit on the product of the intrinsic neutrino magnetic moment and the value of the solar magnetic field \mu B< 2.3\times 10^{-21}MeV95LMA MeV 95% CL (for LMA (\Delta m^2, \tan^2\theta)values).Limitsonneutrinotransitionmomentsarealsoobtained.Forrealisticvaluesofotherastrophysicalsolarparameterstheseupperlimitswouldimplythattheneutrinomagneticmomentisconstrainedtobe,inthemostconservativecase, values). Limits on neutrino transition moments are also obtained. For realistic values of other astrophysical solar parameters these upper limits would imply that the neutrino magnetic moment is constrained to be, in the most conservative case, \mu\lsim 3.9\times 10^{-12} \mu_B(95CL)forarelativelysmallfield (95% CL) for a relatively small field B= 50kG.Forhighervaluesofthemagneticfieldweobtain: kG. For higher values of the magnetic field we obtain: \mu\lsim 9.0\times 10^{-13} \mu_Bforfield for field B= 200kGand kG and \mu\lsim 2.0\times 10^{-13} \mu_Bforfield for field B= 1000$ kG at the same statistical significance.Comment: 13 pages, 2 figure

    Muon anomalous magnetic moment in supersymmetric scenarios with an intermediate scale and nonuniversality

    Get PDF
    We analyze the anomalous magnetic moment of the muon (a_{\mu}) in supersymmetric scenarios. First we concentrate on scenarios with universal soft terms. We find that a moderate increase of a_{\mu} can be obtained by lowering the unification scale M_{GUT} to intermediate values 10^{10-12} GeV. However, large values of \tan \beta are still favored. Then we study the case of non-universal soft terms. For the usual value M_{GUT}~10^{16} GeV, we obtain a_{\mu} in the favored experimental range even for moderate \tan \beta regions \tan\beta ~ 5$. Finally, we give an explicit example of these scenarios. In particular, we show that in a D-brane model, where the string scale is naturally of order 10^{10-12} GeV and the soft terms are non universal, a_{\mu} is enhanced with low \tan\beta.Comment: Final version to appear in Phys. Rev. D. Conventions clarified, results in the figures improve

    Procesos de incorporación y preservación de bioclastos en flujos piroclásticos subacuáticos: dos ejemplis y un modelo genético

    Get PDF
    Se ofrecen dos ejemplos de incorporación de bioclastos por parte de coladas piroclásticas en ambiente subacuático. Estos ejemplos proceden del Ordovicico Superior-Silúrico inferior del Sarrabus (Sureste de Cerdeña, Italia) y el Mioceno del Arcuentu (Suroeste de Cerdeña, Italia). Los bioclastos aparecen en ambos casos en el frente de coladas piroclásticas, y se han preservádo en forma de moldes. Tras una exposición detallada de los materiales se propone un modelo genético común para ambos ejemplos, en el que tras la asimilación de los bioclastos en el frente de la colada éstos sufren disolución y se preservan en los raros casos en los que la colada piroclástica se enfrió rápidamente

    Procesos de incorporación y preservación de bioclastos en flujos piroclásticos subacuáticos: dos ejemplis y un modelo genético

    Get PDF
    Se ofrecen dos ejemplos de incorporación de bioclastos por parte de coladas piroclásticas en ambiente subacuático. Estos ejemplos proceden del Ordovicico Superior-Silúrico inferior del Sarrabus (Sureste de Cerdeña, Italia) y el Mioceno del Arcuentu (Suroeste de Cerdeña, Italia). Los bioclastos aparecen en ambos casos en el frente de coladas piroclásticas, y se han preservádo en forma de moldes. Tras una exposición detallada de los materiales se propone un modelo genético común para ambos ejemplos, en el que tras la asimilación de los bioclastos en el frente de la colada éstos sufren disolución y se preservan en los raros casos en los que la colada piroclástica se enfrió rápidamente

    Prison de-radicalization strategies, programs and risk assessment tools in Europe

    Get PDF
    open3noWith financial support from the Criminal Justice Programme of the European Union Call: JUST-AG-2016-03 Project Number: 763710 Project Acronym: PRP Duration (months): 24 Project Title: European Prison Observatory. Prison de-radicalization strategies, programmes and risk assessment tools in Europe. Coordinator: ANTIGONE ONLUS Alvise Sbraccia wrote the Part One of this Report; Daniela Ronco wrote Part Two, chapters 1, 2, 3, 4, 5, 6, 7, 8; Giovanni Torrente wrote Part Two, chapters 9-10. The conclusions have been written by all the authorsThis project’s goal is to assess strategies and programmes which prevent, deter and counter radicalization in prison and identify and analyse good practices regarding new or existing de-radicalization, disengagement and rehabilitation programmes and risk assessment tools. The analysis has been carried out having in mind the international and European standards for the the protection of detainees' rights. Research incorporates qualitative and quantitative data analysis on official government documents and interviews with stakeholders from prison administration and management, prison staff, Imams, chaplains and other religious representatives.openDaniela Ronco, Alvise Sbraccia, Giovanni TorrenteDaniela Ronco, Alvise Sbraccia, Giovanni Torrent

    Neutrino Magnetic Moments and Minimal Supersymmetric SO(10) Model

    Full text link
    We examine supersymmetric contributions to transition magnetic moments of Majorana neutrinos. We first give the general formula for it. In concrete evaluations, informations of neutrino mass matrix elements including CP phases are necessary. Using unambiguously determined neutrino mass matrices in recently proposed minimal supersymmetric SO(10) model, the transition magnetic moments are calculated. The resultant neutrino magnetic moments are found to be roughly an order of magnitude larger than those calculated in the standard model extended to incorporate the see-saw mechanism.Comment: 8 pages, 4 figures, the version to be published in International Journal of Modern Physics
    corecore