Supersymmetric Higgs boson pair production at hadron colliders

We study the pair production of neutral Higgs bosons through gluon fusion at hadron colliders in the framework of the minimal supersymmetric standard model. We present analytical expressions for the relevant amplitudes, including both quark and squark loop contributions, and allowing for mixing between the superpartners of left- and right-handed quarks. Squark loop contributions can increase the cross section for the production of two CP-even Higgs bosons by more than two orders of magnitude, if the relevant trilinear soft breaking parameter is large and the mass of the lighter squark eigenstate is not too far above its current lower bound. In the region of large tan β, neutral Higgs boson pair production might even be observable in the 4b final state during the next run of the Fermilab Tevatron collider. ©1999 The American Physical Society.

Strong-interaction effects in stop pair production at e+e- colliders

We discuss perturbative and non-perturbative strong-interaction effects in the pair production of stop squarks (t̃1) at e+e- colliders. Events with an additional hard gluon allow to detect or exclude t̃1t̃*1 production even in scenarios with very small mass splitting between ti and an invisible lightest supersymmetric particle (LSP). Such events can also help to establish that t̃1 transforms as a triplet under SU(3)C. We also carefully study non-perturbative t̃1 fragmentation, which is currently not well understood: not only is the t̃1 fragmentation function not known very well, but also there are ambiguities in the algorithm employed to model fragmentation. We present numerical results both for CERN LEP-183 and for a proposed future e+e- collider operating at center-of-mass energy s1/2 = 500 GeV.

Bose-Einstein correlations in W-pair decays

Bose-Einstein correlations are studied in semileptonic (WW → qq̄lv) and fully hadronic (WW → qq̄qq̄) W-pair decays with the ALEPH detector at LEP at centre-of-mass energies of 172, 183 and 189 GeV. They are compared with those made at the Z peak after correction for the different flavour compositions. A Monte Carlo model of Bose-Einstein correlations based on the JETSET hadronization scheme was tuned to the Z data and reproduces the correlations in the WW → qq̄lv events. The same Monte Carlo reproduces the correlations in the WW → qq̄qq̄ channel assuming independent fragmentation of the two W's. A variant of this model with Bose-Einstein correlations between decay products of different W's is disfavoured. (C) 2000 Published by Elsevier Science B.V.

Supersymmetric Higgs boson pair production: Discovery prospects at hadron colliders

We study the potential of hadron colliders in the search for the pair production of neutral Higgs bosons in the framework of the minimal supersymmetric standard model. We perform a detailed signal and background analysis, working out efficient kinematical cuts for the extraction of the signal. The important role of squark loop contributions to the signal is re-emphasized. If the signal is sufficiently enhanced by these contributions, it could even be observable at the next run of the upgraded Tevatron collider in the near future. At the LHC the pair production of light and heavy Higgs bosons might be detectable simultaneously.

Taxonomic importance of the prefemoral process of the first pair of legs in males of the genus Pseudonannolene (Diplopoda, Spirostreptida)

The first pair of legs in males of some groups of diplopods is modified, having a large coxa and oral projecting prefemoral process; in the family Spirostreptidae (Spirostreptida) this structure has relevance on the genus level. This paper discusses the shape, presence, and absence of the prefemoral process in the genus Pseudonannolene (Pseudonannolenidae, Spirostreptida) and suggests that this structure is an important taxonomic character in this genus and can be used for distinguishing some species.

ZmPUMP encodes a fully functional monocot plant uncoupling mitochondrial protein whose affinity to fatty acid is increased with the introduction of a His pair at the second matrix loop

Uncoupling proteins (UCPs) are specialized mitochondrial transporter proteins that uncouple respiration from ATP synthesis. In this study, cDNA encoding maize uncoupling protein (ZmPUMP) was expressed in Escherichia coli and recombinant ZmPUMP reconstituted in liposomes. ZmPUMP activity was associated with a linoleic acid (LA)-mediated H+ efflux with Km of 56.36 ± 0.27 μM and Vmax of 66.9 μmol H+ min-1 (mg prot)-1. LA-mediated H+ fluxes were sensitive to ATP inhibition with Ki of 2.61 ± 0.36 mM (at pH 7.2), a value similar to those for dicot UCPs. ZmPUMP was also used to investigate the importance of a histidine pair present in the second matrix loop of mammalian UCP1 and absent in plant UCPs. ZmPUMP with introduced His pair (Lys155His and Ala157His) displayed a 1.55-fold increase in LA-affinity while its activity remained unchanged. Our data indicate conserved properties of plant UCPs and suggest an enhancing but not essential role of the histidine pair in proton transport mechanism. © 2006 Elsevier Inc. All rights reserved.

Genetic divergence in Eucalyptus spp. clones by molecular RAPD markers

The genetic divergence in 20 Eucalyptus spp. clones was evaluated by multivariate techniques based on 167 RAPD markers, of which 155 were polymorphic and 12 monomorphic. The measures of genetic distances were obtained by the arithmetic complement of the coefficients of Jaccard and of Sorenso-Nei and Li and evaluated by the hierarchical methods of Single Linkage clustering and Unweighted Pair Group Method with Arithmetic Mean (UPGMA). Independent of the dissimilarity coefficient, the greatest divergence was found between clones 7 and 17 and the smallest between the clones 11 and 14. Clone clustering was little influenced by the applied procedure so that, adopting the same percentage of divergence, the UPGMA identified two groups less for the coefficient of Sorenso-Nei and Li. The clones evidenced considerable genetic divergence, which is partly associated to the origin of the study material. The clusters formed by the UPGMA clustering algorithm associated to the arithmetic complement of Jaccard were most consistent.

Search for resonant pair production of neutral long-lived particles decaying to bb̄ in pp̄ collisions at s=1.96TeV

We report on a first search for resonant pair production of neutral long-lived particles (NLLP) which each decay to a bb̄ pair, using 3.6fb-1 of data recorded with the D0 detector at the Fermilab Tevatron collider. We search for pairs of displaced vertices in the tracking detector at radii in the range 1.6-20cm from the beam axis. No significant excess is observed above background, and upper limits are set on the production rate in a hidden-valley benchmark model for a range of Higgs boson masses and NLLP masses and lifetimes. © 2009 The American Physical Society.

Human capital formation and the linkage between trade and poverty: the cases of Costa Rica and Nicaragua

Includes bibliography

Human capital formation and the linkage between trade and poverty: the cases of Costa Rica and Nicaragua

Includes bibliography

Zeros of Jacobi-Sobolev orthogonal polynomials following non-coherent pair of measures

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Search for violation of Lorentz invariance in top quark pair production and decay

Using data collected with the D0 detector at the Fermilab Tevatron Collider, corresponding to 5.3fb -1 of integrated luminosity, we search for violation of Lorentz invariance by examining the tt̄ production cross section in lepton+jets final states. We quantify this violation using the standard-model extension framework, which predicts a dependence of the tt̄ production cross section on sidereal time as the orientation of the detector changes with the rotation of the Earth. Within this framework, we measure components of the matrices (c Q) μν33 and (c U) μν33 containing coefficients used to parametrize violation of Lorentz invariance in the top quark sector. Within uncertainties, these coefficients are found to be consistent with zero. © 2012 American Physical Society.

Search for a narrow, spin-2 resonance decaying to a pair of Z bosons in the qq̄ℓ+ℓ- final state

Results are presented from a search for a narrow, spin-2 resonance decaying into a pair of Z bosons, with one Z-boson decaying into leptons (e+e- or μ+μ-) and the other into jets. An example of such a resonance is the Kaluza-Klein graviton, GKK, predicted in Randall-Sundrum models. The analysis is based on a 4.9 fb-1 sample of proton-proton collisions at a center-of-mass energy of 7 TeV, collected with the CMS detector at the LHC. Kinematic and topological properties including decay angular distributions are used to discriminate between signal and background. No evidence for a resonance is observed, and upper limits on the production cross sections times branching fractions are set. In two models that predict Z-boson spin correlations in graviton decays, graviton masses are excluded lower than a value which varies between 610 and 945 GeV, depending on the model and the strength of the graviton couplings. © 2012 CERN.

Search for pair production of third-generation leptoquarks and top squarks in pp collisions at √s=7 TeV

Results are presented from a search for the pair production of third-generation scalar and vector leptoquarks, as well as for top squarks in R-parity-violating supersymmetric models. In either scenario, the new, heavy particle decays into a τ lepton and a b quark. The search is based on a data sample of pp collisions at √s=7 TeV, which is collected by the CMS detector at the LHC and corresponds to an integrated luminosity of 4.8 fb -1. The number of observed events is found to be in agreement with the standard model prediction, and exclusion limits on mass parameters are obtained at the 95% confidence level. Vector leptoquarks with masses below 760 GeV are excluded and, if the branching fraction of the scalar leptoquark decay to a τ lepton and a b quark is assumed to be unity, third-generation scalar leptoquarks with masses below 525 GeV are ruled out. Top squarks with masses below 453 GeV are excluded for a typical benchmark scenario, and limits on the coupling between the top squark, τ lepton, and b quark, λ333′ are obtained. These results are the most stringent for these scenarios to date. © 2013 CERN.

Thoughts on industrialization, linkage and growth

Examina algunos aspectos que debieran ser considerados al preparar una nueva estrategia de industrializacion que permita hacer frente a los desequilibrios externos y encarar la situacion internacional previsible para los proximos anos.