25 research outputs found

    Volume stabilization via αâ€Č corrections in type IIB theory with fluxes

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    We consider the type IIB string theory in the presence of various extra 7/-brane pairs compactified on a warped Calabi-Yau threefold that admits a conifold singularity. We demonstrate that the volume modulus can be stabilized perturbatively at a non-supersymmetric AdS4/dS4 vacuum by the effective potential that includes the stringy (α')3 correction obtained by Becker et al. together with a combination of positive tension and anomalous negative tension terms generated by the additional 7-brane-antibrane pairs

    The G2G_2-MSSM - An MM Theory motivated model of Particle Physics

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    We continue our study of the low energy implications of MM theory vacua on G2G_2 manifolds, undertaken in \cite{Acharya:2007rc,Acharya:2006ia}, where it was shown that the moduli can be stabilized and a TeV scale generated, with the Planck scale as the only dimensionful input. A well-motivated phenomenological model - the G2G_2-MSSM, can be naturally defined within the above framework. In this paper, we study some of the important phenomenological features of the G2G_2-MSSM. In particular, the soft supersymmetry breaking parameters and the superpartner spectrum are computed. The G2G_2-MSSM generically gives rise to light gauginos and heavy scalars with wino LSPs when one tunes the cosmological constant. Electroweak symmetry breaking is present but fine-tuned. The G2G_2-MSSM is also naturally consistent with precision gauge coupling unification. The phenomenological consequences for cosmology and collider physics of the G2G_2-MSSM will be reported in more detail soon.Comment: 42 pages, 7 figures, one figure corrected, reference adde

    Non-Thermal Dark Matter and the Moduli Problem in String Frameworks

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    We address the cosmological moduli/gravitino problems and the issue of too little thermal but excessive non-thermal dark matter from the decays of moduli. The main examples we study are the G2-MSSM models arising from M theory compactifications, which allow for a precise calculation of moduli decay rates and widths. We find that the late decaying moduli satisfy both BBN constraints and avoid the gravitino problem. The non-thermal production of wino LSPs, which is a prediction of G2-MSSM models, gives a relic density of about the right order of magnitude

    Explaining the Electroweak Scale and Stabilizing Moduli in M Theory

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    In a recent paper \cite{Acharya:2006ia} it was shown that in MM theory vacua without fluxes, all moduli are stabilized by the effective potential and a stable hierarchy is generated, consistent with standard gauge unification. This paper explains the results of \cite{Acharya:2006ia} in more detail and generalizes them, finding an essentially unique de Sitter (dS) vacuum under reasonable conditions. One of the main phenomenological consequences is a prediction which emerges from this entire class of vacua: namely gaugino masses are significantly suppressed relative to the gravitino mass. We also present evidence that, for those vacua in which the vacuum energy is small, the gravitino mass, which sets all the superpartner masses, is automatically in the TeV - 100 TeV range.Comment: 73 pages, 39 figures, Minor typos corrected, Figures and References adde

    Non-thermal Dark Matter and the Moduli Problem in String Frameworks

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    We address the cosmological moduli/gravitino problems and the issue of too little thermal but excessive non-thermal dark matter from the decays of moduli. The main examples we study are the G2-MSSM models arising from M theory compactifications, which allow for a precise calculation of moduli decay rates and widths. We find that the late decaying moduli satisfy both BBN constraints and avoid the gravitino problem. The non-thermal production of wino LSPs, which is a prediction of G2-MSSM models, gives a relic density of about the right order of magnitude.Comment: 41 pages, 5 figures, references and minor comments adde

    NSeq: a multithreaded Java application for finding positioned nucleosomes from sequencing data

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    We introduce NSeq, a fast and efficient Java application for finding positioned nucleosomes from the high-throughput sequencing of MNase-digested mononucleosomal DNA. NSeq includes a user-friendly graphical interface, computes false discovery rates (FDRs) for candidate nucleosomes from Monte Carlo simulations, plots nucleosome coverage and centers, and exploits the availability of multiple processor cores by parallelizing its computations. Java binaries and source code are freely available at https://github.com/songlab/NSeq. The software is supported on all major platforms equipped with Java Runtime Environment 6 or later

    Volume Stabilization via αâ€Č\alpha^\prime Corrections in Type IIB Theory with Fluxes

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    We consider the Type IIB string theory in the presence of various extra 7/7ˉ7/\bar 7-brane pairs compactified on a warped Calabi-Yau threefold that admits a conifold singularity. We demonstrate that the volume modulus can be stabilized perturbatively at a non-supersymmetric AdS4/dS4AdS_4/dS_4 vacuum by the effective potential that includes the stringy (αâ€Č)3(\alpha^\prime)^3 correction obtained by Becker {\it et al.} together with a combination of positive tension and anomalous negative tension terms generated by the additional 7-brane-antibrane pairs.Comment: 20 pages, 4 figures, parts of introduction and conclusions are modifie

    Kahler Independence of the G2-MSSM

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    The G2-MSSM is a model of particle physics coupled to moduli fields with interesting phenomenology both for colliders and astrophysical experiments. In this paper we consider a more general model - whose moduli Kahler potential is a completely arbitrary G2-holonomy Kahler potential and whose matter Kahler potential is also more general. We prove that the vacuum structure and spectrum of BSM particles is largely unchanged in this much more general class of theories. In particular, gaugino masses are still supressed relative to the gravitino mass and moduli masses. We also consider the effects of higher order corrections to the matter Kahler potential and find a connection between the nature of the LSP and flavor effects.Comment: Final version, matches the version published in JHE

    Stabilizing All Kahler Moduli in Type IIB Orientifolds

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    We describe a simple and robust mechanism that stabilizes all Kahler moduli in Type IIB orientifold compactifications. This is shown to be possible with just one non-perturbative contribution to the superpotential coming from either a D3-instanton or D7-branes wrapped on an ample divisor. This moduli-stabilization mechanism is similar to and motivated by the one used in the fluxless G_2 compactifications of M-theory. After explaining the general idea, explicit examples of Calabi-Yau orientifolds with one and three Kahler moduli are worked out. We find that the stabilized volumes of all two- and four-cycles as well as the volume of the Calabi-Yau manifold are controlled by a single parameter, namely, the volume of the ample divisor. This feature would dramatically constrain any realistic models of particle physics embedded into such compactifications. Broad consequences for phenomenology are discussed, in particular the dynamical solution to the strong CP-problem within the framework.Comment: RevTeX, 24 pages, 2 tables, 1 figure
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