1,415 research outputs found
Measuring the muon's anomalous magnetic moment to 0.14 ppm
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)
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
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
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?
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
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
The New Muon Collaboration at Fermilab has proposed to measure the
anomalous magnetic moment of the muon, , a factor of four better than
was done in E821 at the Brookhaven AGS, which obtained ppm. The last digit of 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 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
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