1,415 research outputs found

    Measuring the muon's anomalous magnetic moment to 0.14 ppm

    Full text link
    The anomalous magnetic moment (g-2) of the muon was measured with a precision of 0.54 ppm in Experiment 821 at Brookhaven National Laboratory. A difference of 3.2 standard deviations between this experimental value and the prediction of the Standard Model has persisted since 2004; in spite of considerable experimental and theoretical effort, there is no consistent explanation for this difference. This comparison hints at physics beyond the Standard Model, but it also imposes strong constraints on those possibilities, which include supersymmetry and extra dimensions. The collaboration is preparing to relocate the experiment to Fermilab to continue towards a proposed precision of 0.14 ppm. This will require 20 times more recorded decays than in the previous measurement, with corresponding improvements in the systematic uncertainties. We describe the theoretical developments and the experimental upgrades that provide a compelling motivation for the new measurement.Comment: 5 pages, 1 figure, presented at International Nuclear Physics Conference 2010 (INPC 2010

    Urbanismo de Guerra: fortificaciones, reglamentaciones y embellecimiento de la Habana (1786-1799)

    Get PDF
    Urban policy in Havana in the last two decades of the eighteenth century was marked by wars. The geographically strategic position in the Gulf of Mexico determined the city’s urban development, emphasising in defensive constructions through the building and restoration of the city’s four defensive forts. The finance of these constructions generated several problems between the government and the engineers of these fortifications, who were always demanding more funds for their buildings.La política urbanística de La Habana en las dos últimas décadas del siglo XVIII estuvo marcada por las guerras. La situación geoestratégica en el Golfo de México determinó el urbanismo de la ciudad poniendo un marcado énfasis en las construcciones defensivas con la edificación y arreglo de cuatro fuertes destinados a la defensa de la ciudad. La financiación de estas obras constituyó una fuente permanente de discordia entre las instituciones implicadas y los responsables de estas que reclamaban más fondos específicos para su sustento

    Form factors of radiative pion decays in nonlocal chiral quark models

    Get PDF
    We study the radiative pion decay pi+ -> e+ nu_e gamma within nonlocal chiral quark models that include wave function renormalization. In this framework we analyze the momentum dependence of the vector form factor F_V(q^2), and the slope of the axial-vector form factor F_A(q^2) at threshold. Our results are compared with available experimental information and with the predictions given by the NJL model. In addition we calculate the low energy constants l_5 and l_6, comparing our results with the values obtained in chiral perturbation theory.Comment: 22 pages, 1 figure. arXiv admin note: substantial text overlap with arXiv:1011.640

    Vector meson decays from the Extended Chiral Quark Model

    Get PDF
    We derive the the effective lagrangian that describes the interactions among vector, axial-vector mesons and pseudoscalars starting from the extended chiral quark model (ECQM). The results for the low-energy constants of this effective lagrangian have a parametric resemblance with existing predictions based on the Nambu-Jona-Lasinio model (except for some overall signs that we correct), but are numerically different. Therefore a precise measurement of these decay constants can shed some light on the way chiral symmetry breaking is modelled in QCD. Although most of the constants are poorly measured, comparison with phenomenology allows us to determine one of the parameters of the ECQM that could not be fully determined in previous analyses.Comment: 7 pages, revtex

    New era for the coconut sector. What prospects for research?

    Get PDF
    For years and years, the main output of the coconut sector on the international market was copra, crude coconut oil (CNO) and its derivatives. However, since approximately 10 years, we see new products so called “non-traditional” products entering global exchanges. The market growth of these products, mainly coconut water extracted from mature or immature nuts, virgin coconut oil (VCO) cold pressed from the fresh kernel, coconut sugar taken from the sap flowing out of the flower, is exponential. They benefit from the healthy, simple and natural image that is conveyed by the coconut tree in the subconscious minds of the consumers. The craze for this new products create also biggest expectative from the consumers towards the coconut stakeholders. This is why this article will also suggest some tracks of reflection for the research and expert’s communities, who would like to support this expansion, thus contributing to the future of the millions of small coconut farmer

    Mapping surgical coordinates of the sphenopalatine foramen : surgical navigation study

    Get PDF
    Aims to identify measurements that may help intra operative localisation of the sphenopalatine foramen. The study used three dimensional surgical navigation software to study radiological anatomy, in order to define the distances and angulations between identifiable bony landmarks and the sphenopalatine foramen. The distance from the anterior nasal spine to the sphenopalatine foramen was 59 mm (+4 mm; inter observer variation = 0.866; intra observer variation = 0.822). The distance from the piriform aperture to the sphenopalatine foramen was 48 mm (+4 mm; inter observer variation = 0.828; intra observer variation = 0.779). The angle of elevation from the nasal floor to the sphenopalatine foramen was 22 degrees (+3 degrees; inter observer variation = 0.441; intra observer variation = 0.499). The sphenopalatine foramen is consistently identifiable on three dimensional, reconstructed computed tomography scans. Repeatable measurements were obtained. The centre point of the foramen lies 59 mm from the anterior nasal spine at 22 degrees elevation above the plane of the hard palate and 48 mm from the piriform aperture. We discuss how these data could be used to facilitate intra operative location of the sphenopalatine foramen in difficult cases

    Status of the Fermilab Muon (g-2) Experiment

    Full text link
    The New Muon (g2)(g-2) Collaboration at Fermilab has proposed to measure the anomalous magnetic moment of the muon, aμa_\mu, a factor of four better than was done in E821 at the Brookhaven AGS, which obtained aμ=[116592089(63)]×1011a_\mu = [116 592 089 (63)] \times 10^{-11} ±0.54\pm 0.54 ppm. The last digit of aμa_{\mu} is changed from the published value owing to a new value of the ratio of the muon-to-proton magnetic moment that has become available. At present there appears to be a difference between the Standard-Model value and the measured value, at the 3\simeq 3 standard deviation level when electron-positron annihilation data are used to determine the lowest-order hadronic piece of the Standard Model contribution. The improved experiment, along with further advances in the determination of the hadronic contribution, should clarify this difference. Because of its ability to constrain the interpretation of discoveries made at the LHC, the improved measurement will be of significant value, whatever discoveries may come from the LHC.Comment: Proceedings of the PhiPsi09, Oct. 13-16, 2009, Beijing, China, 4 pages 2 figures. Version 2 includes Fermilab report number, minor corrections and one additional referenc
    corecore