5,034 research outputs found

    Novel Higgs decay signals in R-parity violating models

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    In supersymmetric models the lightest Higgs boson may decay with a sizable branching ratio into a pair of light neutralinos. We analyze such decays within the context of the minimal supersymmetric standard model with R-parity violation, where the neutralino itself is unstable and decays into Standard Model fermions. We show that the R-parity violating couplings induce novel Higgs decay signals that might facilitate the discovery of the Higgs boson at colliders. At the LHC, the Higgs may be observed, for instance, through its decay -via two neutralinos- into final states containing missing energy and isolated charged leptons such as l±l,l±l±,3ll^\pm l^\mp, l^\pm l^\pm, 3l, and 4l4l. Another promising possibility is the search for the displaced vertices associated with the neutralino decay. We also point out that Higgs searches at the LHC might additionally provide the first evidence of R-parity violation.Comment: 15 pages, 7 figures. Corrected affiliation

    Symmetrical Observability of Kinematic Parameters in Symmetrical Parallel Mechanisms

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    This article presents an application of symmetry group theory in kinematic identification of parallel mechanisms of nlegs legs -- Kinematic Identification implies the estimation of the actual geometrical parameters (as opposed to nominal ones) of a physical mechanism -- For a symmetric mechanism, KI requires configuring sets of leg positions with symmetrical observability – This article presents as main contributions: (i) a conjecture that allows mapping the symmetries of the mechanism into the active-joint workspace, (ii) a set of necessary conditions to express leg parameters in coordinate systems which allow symmetrical observability, and (iii) a procedure for exploiting symmetries in pose selection for kinematic identification of symmetrical parallel mechanisms -- For the kinematic identification itself, we adopt a divide-and-conquer (DC) identification protocol -discussed by us in another publication- in which each leg of the mechanism is independently identified by using the inverse calibration method -- In this article we emphasize how to exploit the symmetries existent in (nlegs − 1) legs of the parallel mechanism allowing to apply to other legs the symmetry-transformed sample protocol used for the kinematic identification of a reference leg -- The symmetrical observability of sets of leg parameters allows to reduce the costs of the pose selection procedure by a factor of (1/nlegs) compared to a complete DC procedure in which the poses of each leg are selected independently -- The pose selection is carried out only for the reference leg -- For the (nlegs−1) remaining legs the poses are dictated by symmetry operations performed onto the poses of the reference leg -- An application of the symmetrical observability is presented through the simulated kinematic identification of a 3RRR symmetrical parallel mechanismPolytechnic School of the University of São PauloSitio webIndicaciones, Associação Brasileira de Métodos Computacionais em Engenharia, International Association for Computational Mechanics, International Congress and Convention Association, Conheça o São Paulo é Tudo de Bom, Embratur, PETROBRA

    Répartition géographique de la bactériose vasculaire du manioc en Colombie et variabilité de l'agent pathogène

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    Le manioc est une culture importante en Colombie puisqu'elle couvre environ 196 000 ha. L'un des facteurs limitants de la production est une maladie causée par une bactérie : #Xanthomonas axonopodis# pv. #manihotis# (Xam). La distribution géographique de la maladie et son incidence sont précisées dans les différentes zones écologiques de la Colombie. Les souches de cette bactérie collectées dans trois zones ont été caractérisées selon une approche moléculaire, leur agressivité étant évaluée sur la plante. Vingt-six groupes de souches de Xam ont pu être définis et leur répartition dans les 3 zones écologiques analysée. Dans une zone de haute altitude, la variabilité de l'agent pathogène est très faible. L'impact de cette étude pour l'amélioration variétale vis-à-vis de la résistance à la bactériose est discuté. Les perspectives d'étude sur les gènes de résistance sont également abordés. (Résumé d'auteur

    On the connection of Gamma-rays, Dark Matter and Higgs searches at LHC

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    Motivated by the upcoming Higgs analyzes we investigate the importance of the complementarity of the Higgs boson chase on the low mass WIMP search in direct detection experiments and the gamma-ray emission from the Galactic Center measured by the Fermi-LAT telescope in the context of the SU(3)cSU(3)LU(1)NSU(3)_c\otimes SU(3)_L\otimes U(1)_N. We obtain the relic abundance, thermal cross section, the WIMP-nucleon cross section in the low mass regime and network them with the branching ratios of the Higgs boson in the model. We conclude that the Higgs boson search has a profound connection to the dark matter problem in our model, in particular for the case that (MWIMP<60M_{WIMP} < 60 GeV) the BR(H2H \rightarrow 2 WIMPs) 90\gtrsim 90%. This scenario could explain this plateau of any mild excess regarding the Higgs search as well as explain the gamma-ray emission from the galactic center through the bbˉb\bar{b} channel with a WIMP in the mass range of 25-45 GeV, while still being consistent with the current limits from XENON100 and CDMSII. However, if the recent modest excesses measured at LHC and TEVATRON are confirmed and consistent with a standard model Higgs boson this would imply that MWIMP>60 M_{WIMP} > 60 GeV, consequently ruling out any attempt to explain the Fermi-LAT observations.Comment: 8 pages, 9 figure

    Dynamics and Pattern Formation in Large Systems of Spatially-Coupled Oscillators with Finite Response Times

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    We consider systems of many spatially distributed phase oscillators that interact with their neighbors. Each oscillator is allowed to have a different natural frequency, as well as a different response time to the signals it receives from other oscillators in its neighborhood. Using the ansatz of Ott and Antonsen (Ref. \cite{OA1}) and adopting a strategy similar to that employed in the recent work of Laing (Ref. \cite{Laing2}), we reduce the microscopic dynamics of these systems to a macroscopic partial-differential-equation description. Using this macroscopic formulation, we numerically find that finite oscillator response time leads to interesting spatio-temporal dynamical behaviors including propagating fronts, spots, target patterns, chimerae, spiral waves, etc., and we study interactions and evolutionary behaviors of these spatio-temporal patterns

    Leptonic Charged Higgs Decays in the Zee Model

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    We consider the version of the Zee model where both Higgs doublets couple to leptons. Within this framework we study charged Higgs decays. We focus on a model with minimal number of parameters consistent with experimental neutrino data. Using constraints from neutrino physics we (i) discuss the reconstruction of the parameter space of the model using the leptonic decay patterns of both of the two charged Higgses, h1,2+j+νih_{1,2}^{+}\to \ell_{j}^{+}\nu_{i}, and the decay of the heavier charged Higgs, h2+h1+h0h_{2}^{+}\to h^{+}_{1}h^{0}; (ii) show that the decay rate Γ(h1+μ+νi)\Gamma(h_{1}^{+}\to \mu^{+}\nu_{i}) in general is enhanced in comparision to the standard two Higgs doublet model while in some regions of parameter space Γ(h1+μ+νi)\Gamma(h_{1}^{+}\to \mu^{+}\nu_{i}) even dominates over Γ(h1+τ+νi)\Gamma(h_{1}^{+}\to \tau^{+}\nu_{i}).Comment: 25 pages, 9 figure

    Performance of two transferred modules in the Lagunera Region: Water relations

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    Water policy / Performance / Privatization / Irrigation systems / Operations / Maintenance / Irrigation efficiency / Water users' associations / Water rights / Water allocation / Water supply / Water distribution

    The onset of synchronization in large networks of coupled oscillators

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    We study the transition from incoherence to coherence in large networks of coupled phase oscillators. We present various approximations that describe the behavior of an appropriately defined order parameter past the transition, and generalize recent results for the critical coupling strength. We find that, under appropriate conditions, the coupling strength at which the transition occurs is determined by the largest eigenvalue of the adjacency matrix. We show how, with an additional assumption, a mean field approximation recently proposed is recovered from our results. We test our theory with numerical simulations, and find that it describes the transition when our assumptions are satisfied. We find that our theory describes the transition well in situations in which the mean field approximation fails. We study the finite size effects caused by nodes with small degree and find that they cause the critical coupling strength to increase.Comment: To appear in PRE; Added an Appendix, a reference, modified two figures and improved the discussion of the range of validity of perturbative approache

    Impact assessment of irrigation management transfer in the Alto Rio Lerma Irrigation District, Mexico

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    Irrigation managementPrivatizationAssessmentEconomic aspectsLegal aspectsData collectionWater rightsWater allocationWater distributionGroundwaterFinancingMaintenanceOperationsAgricultural productionWater users' associationsFarmer participation

    Modification of the National Weather Service Distributed Hydrologic Model for subsurface water exchanges between grids

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    To account for spatial variability of precipitation, as well as basin physiographic properties, the National Weather Service (NWS) has developed a distributed version of its hydrologic component, termed the Hydrology Laboratory-Research Distributed Hydrologic Model (HL-RDHM). Because channels are the only source of water exchange between neighboring computational elements, the absence of such exchange has been identified as a weakness in the model. The primary objective of this paper is to modify the model structure to account for subsurface water exchanges without dramatically altering the conceptual framework of the water balance module. The subsurface exchanges are established by partitioning the slow response components released from the lower layer storages into two parts: the first part involves the grid's conceptual channel, while the second is added to the lower layer storages of the downstream pixel. Realizing the deficiency of the water balance module to locate the lower zone layers in sufficient depths, a complementary study is conducted to test the feasibility of further improvement in the modified model by equally shifting downward the lower zone layers of all pixels over the basin. The Baron Fork at Eldon, Oklahoma, is chosen as the test basin. Ten years of grid-based multisensor precipitation data are used to investigate the effects of the modification, plus shifting the lower zone layers on model performance. The results show that the modified-shifted HL-RDHM can markedly improve the streamflow simulations at the interior point, as well as very high peak-flow simulations at the basin's outlet. Copyright 2011 by the American Geophysical Union
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