Chromomagnetic Dipole Moment of the Top Quark Revisited

We study the complete one-loop contributions to the chromagnetic dipole moment $\Delta\kappa$ of the top quark in the Standard Model, two Higgs doublet models, topcolor assited technicolor models (TC2), 331 models and extended models with a single extra dimension. We find that the SM predicts $\Delta\kappa = - 0.056$ and that the predictions of the other models are also consitent with the constraints imposed on $\Delta\kappa$ by low-energy precision measurements.Comment: 20 pages, 5 figures, Updat

FCNC Top Quark Decays in Extra Dimensions

The flavor changing neutral top quark decay t -> c X is computed, where X is a neutral standard model particle, in a extended model with a single extra dimension. The cases for the photon, X= \gamma$, and a Standard Model Higgs boson, X = H, are analyzed in detail in a non-linear$R_\xi gauge. We find that the branching ratios can be enhanced by the dynamics originated in the extra dimension. In the limit where 1/R >> ->, we have found Br(t -> c \gamma) \simeq 10^{-10} for 1/R = 0.5 TeV. For the decay t -> c H, we have found Br(t -> cH) \simeq 10^{-10} for a low Higgs mass value. The branching ratios go to zero when 1/R -> \infty.Comment: Accepted to be published in the Europ. Phys. Jour. C; 16 pages, 2 figure

Rare decay Z --> neutrino antineutrino photon photon via quartic gauge boson couplings

We present a detailed calculation of the rare decay Z --> neutrino antineutrino photon photon via the quartic neutral gauge boson coupling Z-Z-photon-photon in the framework of the effective Lagrangian approach. The current experimental bound on this decay mode is then used to constrain the coefficients of this coupling. It is found that the bounds obtained in this way, of the order of $10^{-1}$, are weaker than the ones obtained from the analysis of triple-boson production at LEP-2Comment: 5 pages, 2 figures, to appear in Physical Review D Brief Report

Bounds on the dipole moments of the tau-neutrino via the process e+e−→ννˉγe^{+}e^{-}\rightarrow \nu \bar \nu \gamma in a 331 model

We obtain limits on the anomalous magnetic and electric dipole moments of the $\nu_{\tau}$ through the reaction $e^{+}e^{-}\rightarrow \nu \bar \nu \gamma$ and in the framework of a 331 model. We consider initial-state radiation, and neglect $W$ and photon exchange diagrams. The results are based on the data reported by the L3 Collaboration at LEP, and compare favorably with the limits obtained in other models, complementing previous studies on the dipole moments.Comment: 13 pages, 4 figures, to be published in The European Physical J C. arXiv admin note: substantial text overlap with arXiv:hep-ph/060527

Polarized Single Top Quark Production in e\gamma Collision and Anomalous Wtb Couplings

We investigate the potential of $e\gamma$ collisions to probe anomalous $Wtb$ couplings via the polarized single top quark production process $e^{+} \gamma \to t \bar{b} \bar{\nu_{e}}$. We find 95% confidence level limits on the anomalous coupling parameters $F_{2L}$ and $F_{2R}$ with an integrated luminosity of $500 fb^{-1}$ and $\sqrt{s}=0.5, 1$ and 1.5 TeV energies. The effects of top quark spin polarization on the anomalous $Wtb$ couplings are discussed. It is shown that polarization leads to a considerable improvement in the sensitivity limits.Comment: published versio

The Top Quark Decay Vertex in Standard Model Extensions

New physics interactions can affect the strength and structure of the $tbW$ vertex. We investigate the magnitudes and phases of "anomalous" contributions to this vertex in a two-Higgs doublet and the minimal supersymmetric extension of the standard model, and in a top-color assisted technicolor (TC2) model. While the magnitudes of the anomalous couplings remain below 1 percent in the first two models, TC2 interactions can reduce the left-chiral coupling $f_L$ by several percent.Comment: Latex, 27 pages, 14 figure

Search for anomalous Wtb couplings in single top quark production in ppbar collisions at sqrt(s) = 1.96 TeV

We present new direct constraints on a general $Wtb$ interaction using data corresponding to an integrated luminosity of 5.4 fb$^{-1}$ collected by the D0 detector at the Tevatron $p\bar{p}$ collider. The standard model provides a purely left-handed vector coupling at the $Wtb$ vertex, while the most general, lowest dimension Lagrangian allows right-handed vector and left- or right-handed tensor couplings as well. We obtain precise limits on these anomalous couplings by comparing the data to the expectations from different assumptions on the $Wtb$ coupling.Comment: Submitted to Phys. Lett.

Presencia de Epilobium brachicarpum C. Presl. como infestante en los frutales de Extremadura

Unpublishe

A longitudinal evaluation of growth outcomes at hospital discharge of very-low-birth-weight preterm infants

Background/Objectives:To quantify the rate of progressive failure of very-low-birth-weight (VLBW) infants over time in the neonatal intensive care unit to meet growth milestones.Subjects/Methods:In a prospective longitudinal study, 114 VLBW preterm infants (≤1500 g) of both sexes, with normal and/or low weight for gestational age were included. At the start, weight, length, mid-upper arm (MUAC), thigh and cephalic circumferences were measured. Weight/age (W/A), length/age and weight/length (±2 z-score) indices were calculated. All measurements were taken at inclusion, at 7, 15 and 30 days of hospitalization. Chi-square test, analysis of variance and repeated-measures tests were estimated.Results:Thirteen cases (14%) died and were excluded soon after the first determinations. In all, 9 (8.9%) died during the study, 12 (11.9%) were discharged before 30 days of life and 80 (79.2%) completed the study. At 7 days, the percentage of preterm infants with an index of W/A <-2 z-scores increased from 44 to 67% (44-68 subjects; P<0.01), with no changes afterwards; the indicator MUAC <-2 z-scores increased at 7 days from 23 to 49% (23-49 subjects); at 15 from 23 to 65% (23-61 subjects) and at 30 days from 23 to 79% (23-63 subjects; P<0.001).Conclusions:Clinicians could use these indicators for earlier detection of growth failure in VLBW infants in order to target more aggressive nutrition early. © 2012 Macmillan Publishers Limited. All rights reserved

A new GPS velocity field for the Pacific Plate - Part 2: Implications for fault slip rates in western California

Background/Objectives:To quantify the rate of progressive failure of very-low-birth-weight (VLBW) infants over time in the neonatal intensive care unit to meet growth milestones.Subjects/Methods:In a prospective longitudinal study, 114 VLBW preterm infants (?1500 g) of both sexes, with normal and/or low weight for gestational age were included. At the start, weight, length, mid-upper arm (MUAC), thigh and cephalic circumferences were measured. Weight/age (W/A), length/age and weight/length ( 2 z-score) indices were calculated. All measurements were taken at inclusion, at 7, 15 and 30 days of hospitalization. Chi-square test, analysis of variance and repeated-measures tests were estimated.Results:Thirteen cases (14%) died and were excluded soon after the first determinations. In all, 9 (8.9%) died during the study, 12 (11.9%) were discharged before 30 days of life and 80 (79.2%) completed the study. At 7 days, the percentage of preterm infants with an index of W/A <-2 z-scores increased from 44 to 67% (44-68 subjects; P<0.01), with no changes afterwards; the indicator MUAC <-2 z-scores increased at 7 days from 23 to 49% (23-49 subjects); at 15 from 23 to 65% (23-61 subjects) and at 30 days from 23 to 79% (23-63 subjects; P<0.001).Conclusions:Clinicians could use these indicators for earlier detection of growth failure in VLBW infants in order to target more aggressive nutrition early. " 2012 Macmillan Publishers Limited. All rights reserved.",,,,,,"10.1038/ejcn.2011.191",,,"http://hdl.handle.net/20.500.12104/39004","http://www.scopus.com/inward/record.url?eid=2-s2.0-84859446990&partnerID=40&md5=4c2984c0bf348f265c99d19dd519112