1,418 research outputs found

    Exploring singlet deflection of gauge mediation

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    We embed the Next-to Minimal Supersymmetric Standard Model into gauge mediation of supersymmetry breaking and study the phenomenology of scenarios where the gauge-mediation contributions to soft parameters are deflected by superpotential interactions of the gauge singlet with the messenger fields and the Higgs doublets. This kind of models provide a satisfactory solution to the mu-b_mu problem of gauge mediation, compatible with the adequate pattern of electroweak symmetry breaking and a realistic spectrum with supersymmetric partners at the TeV scale without requiring a significant fine tuning.Comment: Latex 18 pages, 4 eps figures. Minor corrections, version published in Phys. Rev.

    Indirect Effect of Supersymmetric Triplets in Stop Decays

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    We study an extension of the minimal supersymmetric standard model with a zero hypercharge triplet, and the effect that such a particle has on stop decays. This model has the capability of predicting a 125.5 GeV Higgs even in the presence of light stops and it can modify the diphoton rate by means of the extra charged fermion triplet coupled to the Higgs. Working in the limit where the scalar triplet decouples, and with small values of mA, we find that the fermion triplet can greatly affect the branching ratios of the stops, even in the absence of a direct stop-triplet coupling. We compare the triplet extension with the MSSM and discuss how the additional fields affect the search for stop pair production.Comment: pdfLateX, 16 pages, 7 figures, 2 tables, Typos, minor changes. Version published in JHE

    Electroweak Limits on General New Vector Bosons

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    We study extensions of the Standard Model with general new vector bosons. The full Standard Model gauge symmetry is used to classify the extra vectors and constrain their couplings. We derive the corresponding effective Lagrangian, valid at energies lower than the mass of the extra vectors, and use it to extract limits from electroweak precision observables, including LEP 2 data. We consider both universal and nonuniversal couplings to fermions. We study the interplay of several extra vectors, which can have the effect of opening new regions in parameter space. In particular, it allows to explain the anomaly in the bottom forward-backward asymmetry with perturbative couplings. Finally, we analyze quantitatively the implications for the Higgs mass.Comment: Latex 50 pages, 12 eps figures. Typos fixed, comments and references adde

    Looking for signals beyond the neutrino Standard Model

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    Any new neutrino physics at the TeV scale must include a suppression mechanism to keep its contribution to light neutrino masses small enough. We review some seesaw model examples with weakly broken lepton number, and comment on the expected effects at large colliders and in neutrino oscillations.Comment: LaTeX 10 pages, 9 PS figures. Contribution to the Proceedings of the XXXI International School of Theoretical Physics "Matter To The Deepest" Ustron, Poland, September 5-11, 2007. Typos correcte

    Impact of extra particles on indirect Z' limits

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    We study the possibility of relaxing the indirect limits on extra neutral vector bosons by their interplay with additional new particles. They can be systematically weakened, even below present direct bounds at colliders, by the addition of more vector bosons and/or scalars designed for this purpose. Otherwise, they appear to be robust.Comment: Latex 23 pages, 8 eps figures. Minor changes, version published in Phys. Rev.

    The tourism potential of board regions - endogenous resources and destination image evaluation

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    Tourism has an enormous potential while instrument of regional development. However, the opportunities are not the same for each territory and it is easy to understand that, considering the resources available, not every region has the choice to base its development strategy in the touristic industry. Taking this in consideration, the mission of classifying, evaluating and compare, from a consistent and realistic point a view, several groups of tourist resources became a necessary task and a precondition to define the touristic vocation of a region. This approach allows to select the best alternative to tourism development. The paper attempts to catalogue the tourist resources of the selected territory and to evaluate the different sort of resources available, using several classification approaches, aiming to calculate its index of touristic potential. We believe that the before mention methodology might be a valuable instrument to identify the strongnesses and weaknesses of the Minho-Lima sub-region (Portugal) in what refers to its touristic development, as well as the degree of integration of the tourism sector in the local productive system.

    The Minho-Lima sub-region as a common destination: tourist potential and agents’ commitment on it

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    Empirical evidence shows that tourism can give a real contribution to regional development and, in the case of certain remote and economic lagged territories, it is one of the best placed sectors to achieve this goal. This as to do, namely, with the possibility of making use of endogenous resources of territories. In the case of the Minho-Lima sub-region, an important tourist potential exists coming from the variety and singularity of its resources - the beauty of its landscapes, the architectonic wealth of secular buildings, and the exuberance of the gastronomy and many of its cultural manifestations. Taking this in view, this paper attempts to catalogue and evaluate the tourist resources of Minho-Lima, as well as to analyze the complementary elements and the external factors related with the image of the destination. The methodology followed relies on a two-stage process. Firstly, taking the primary components, the consistency of the territory as a tourist destination was analysed, evaluating its tourism potential. In a second stage, considering the secondary elements, the components of the image of the common tourist destination were evaluated through the study of local, regional and national promotion strategies, in what brochures and web sites are concerned. The ultimate goal is to check the perception of the territory as a common destination and agents’ commitment on it
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