2,204 research outputs found

    The Fourth Generation t-prime in Extensions of the Standard Model

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    We study the effects of a fourth generation t' quark in various extensions of the standard model. In the Randall-Sundrum model, the decay t'--> t Z has a large branching ratio that could be detected at the Large Hadron Collider (LHC). We also look at the two-Higgs doublet models I, II and III, and note that, in the latter, the branching ratio of t' --> t H, where H is a Higgs scalar or pseudoscalar, is huge and we discuss detection at the LHC. A few comments about the minimal supersymmetric standard model are also included.Comment: 4 pages, 2 figures. Version to be published in Phys. Rev.

    A Supersymmetric Model with Dirac Neutrino Masses

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    New models have recently been proposed in which a second Higgs doublet couples only to the lepton doublets and right-handed neutrinos, yielding Dirac neutrino masses. The vacuum value of this second "nu-Higgs" doublet is made very small by means of a very softly-broken Z2Z_2 or U(1) symmetry. The latter is technically natural and avoids fine-tuning and very light scalars. We consider a supersymmetric version of this model, in which two additional doublets are added to the MSSM. If kinematically allowed, the decay of the heavy MSSM scalar into charged nu-Higgs scalars will yield dilepton events which can be separated from the W-pair background. In addition, the nu-Higgsinos can lead to very dramatic tetralepton, pentalepton and hexalepton events which have negligible background and can be detected at the LHC and the Tevatron.Comment: 18 pages, 3 figures, 6 tables; PRD versio

    The Supersymmetric Leptophilic Higgs Model

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    In the leptophilic model, one Higgs doublet couples to quarks and another couples to leptons. We study the supersymmetric version of this model, concentrating on the tightly constrained Higgs sector, which has four doublets. Constraints from perturbativity, unitarity, and LEP bounds are considered. It is found that the lightest Higgs, h, can have a mass well below 114 GeV, and for masses below 100 GeV will have a substantially enhanced branching ratio into tau pairs. For this region of parameter space, traditional production mechanisms (Higgs-strahlung, W fusion and gluon fusion) are suppressed, but it may be produced in the decay of heavier particles. The second lightest Higgs has a mass of approximately 110 GeV for virtually all of parameter space, with Standard Model couplings, and thus an increase of a few GeV in the current lower bound on the Standard Model Higgs mass would rule out the model. The two heavier Higgs are both gauge-phobic, one decays almost entirely into b pairs and can be produced via gluon fusion while the other decays almost entirely into tau pairs but can't be easily produced.Comment: 21 pages, 6 figure

    Supersymmetric leptophilic Higgs model

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    In the leptophilic model, one Higgs doublet couples to quarks and another couples to leptons. We study the supersymmetric version of this model, concentrating on the tightly constrained Higgs sector, which has four doublets. Constraints from perturbativity, unitarity, and LEP bounds are considered. It is found that the lightest Higgs, h, can have a mass well below 114 GeV, and for masses below 100 GeV will have a substantially enhanced branching ratio into tau pairs. For this region of parameter space, traditional production mechanisms (Higgs-strahlung, W fusion, and gluon fusion) are suppressed, but it may be produced in the decay of heavier particles. The second lightest Higgs has a mass of approximately 110 GeV for virtually all of parameter space, with standard model couplings, and thus an increase of a few GeV in the current lower bound on the standard model Higgs mass would rule out the model. The two heavier Higgs are both gauge phobic, one decays almost entirely into b (b) over bar and can be produced via gluon fusion while the other decays almost entirely into tau(+)tau(-) but cannot be easily produced

    Developing a National Perspective of Interrelated Preparation: Educational Administration Leading Teacher Leadership Programs

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    This NCPEA Position Paper articulates a national perspective for the development of teacher leadership programs with leadership from educational administration professors. The National Council of Professors of Educational Administration (NCPEA), as the professional organization that provides direction and leadership for its members, presents a vision for dialogue and action to collaboratively develop teacher leadership programs among professors of educational administration and teacher education faculty. We believe that leadership matters and thus we submit there is a sense of urgency for professors to collaboratively develop teacher leadership programs embedded within educational administration programs. It is crucial that these programs articulate knowledge and skills aligned to the national standards for preparing school leaders–leaders who know excellent instruction, but who also are excellent leaders. We envision programs of teacher leadership that include both content and leadership instruction, integrating concepts from curriculum from teacher education, and leadership from educational administration that cultivate skills. These leadership skills are applied in authentic educational environments where experiences are cultivated and guided by both university professors and school practitioners. Appropriate instructional methods for adults provide learning through problem-based concepts where teacher leader candidates can plan, experience, and evaluate on-the-job activities to develop voice, confidence, and actions as leaders and change agents, without ever assuming an official role or title of school administrators. In this document we present three principles for consideration, which correlate with three audiences that could advance these principles

    Energy Choices Revisited : An Examination of the Costs and Benefits of Maine\u27s Energy Policy

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    https://digitalmaine.com/mainewatch_publications/1003/thumbnail.jp
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