556 research outputs found
Cluster Spin Glass Distribution Functions in LaSrCuO
Signatures of the cluster spin glass have been found in a variety of
experiments, with an effective onset temperature that is frequency
dependent. We reanalyze the experimental results and find that they are
characterized by a distribution of activation energies, with a nonzero glass
transition temperature . While the distribution of activation
energies is the same, the distribution of weights depends on the process.
Remarkably, the weights are essentially doping independent.Comment: 5 pages, 5 ps figure
A Discussion on Dirac Field Theory, No-Go Theorems and Renormalizability
We study Dirac field equations coupled to electrodynamics with metric and
torsion fields: we discuss how special spinorial solutions are incompatible
with torsion; eventually these results will be used to sketch a discussion on
the problem of renormalizability of point-like particles.Comment: 10 page
Quantum mass corrections for affine Toda solitons
We calculate the first quantum corrections to the masses of solitons in
imaginary-coupling affine Toda theories using the semi-classical method of
Dashen, Hasslacher and Neveu. The theories divide naturally into those based on
the simply-laced, the twisted and the untwisted non-simply-laced algebras. We
find that the classical relationships between soliton and particle masses found
by Olive {\em et al.\ }persist for the first two classes, but do not appear to
do so naively for the third.Comment: 39pp, .uu compressed dvifile. Revised version alters two references
and includes hep-th no. on Title pag
Brane cosmology with curvature corrections
We study the cosmology of the Randall-Sundrum brane-world where the
Einstein-Hilbert action is modified by curvature correction terms: a
four-dimensional scalar curvature from induced gravity on the brane, and a
five-dimensional Gauss-Bonnet curvature term. The combined effect of these
curvature corrections to the action removes the infinite-density big bang
singularity, although the curvature can still diverge for some parameter
values. A radiation brane undergoes accelerated expansion near the minimal
scale factor, for a range of parameters. This acceleration is driven by the
geometric effects, without an inflaton field or negative pressures. At late
times, conventional cosmology is recovered.Comment: RevTex4, 8 pages, no figures, minor change
Search for lepton-flavor-violating decays at Belle
We have searched for neutrinoless lepton decays into and ,
where stands for an electron or muon, and for a vector meson
(, , , or ), using 543 fb
of data collected with the Belle detector at the KEKB asymmetric-energy
collider. No excess of signal events over the expected background has
been observed, and we set upper limits on the branching fractions in the range
at the 90% confidence level. These upper limits
include the first results for the mode as well as new limits that
are significantly more restrictive than our previous results for the , , and modes.Comment: 7 pages, 16 figure
Measurement of the ratio B(D0->pi+pi-pi0)/B(D0->K-pi+pi0) and the time-integrated CP asymmetry in D0->pi+pi-pi0
We report a high-statistics measurement of the relative branching fraction
B(D0->pi+pi-pi0)/B(D0->K-pi+pi0) using a 532 fb^{-1} data sample collected with
the Belle detector at the KEKB asymmetric-energy e+e- collider. The measured
value of the relative branching fraction is B(D0->pi+pi-pi0)/B(D0->K-pi+pi0) =
(10.12 +/- 0.04(stat) +/- 0.18(syst))x10^{-2} which has an accuracy comparable
to the world average. We also present a measurement of the time-integrated CP
asymmetry in D0->pi+pi-pi0 decay. The result, A_{CP} = (0.43 +/- 1.30)%, shows
no significant CP violation.Comment: 15 pages, 11 figures, submitted to Physics Letters
Search for B -> h(*) nu nubar Decays at Belle
We present a search for the rare decays B -> h(*) nu nubar, where h(*) stands
for a light meson. A data sample of 535 million BBbar pairs collected with the
Belle detector at the KEKB e+e- collider is used. Signal candidates are
required to have an accompanying B meson fully reconstructed in a hadronic mode
and signal-side particles consistent with a single h(*) meson. No significant
signal is observed and we set upper limits on the branching fractions at 90%
confidence level. The limits on B0 -> K*0 nu nubar and B+ -> K+ nu nubar decays
are more stringent than the previous constraints, while the first searches for
B0 -> K0 nu nubar, pi0 nu nubar, rho0 nu nubar, phi nu nubar and B+ -> K*+ nu
nubar, rho+ nu nubar are reported.Comment: 6 pages, 2 figures, submit to PR
Análisis de co-palabras aplicado a los artículos muy citados en Biblioteconomía y Ciencias de la Información (2007-2017)
Se identifican las relaciones entre los conceptos y las áreas temáticas principales dentro de la categoría Biblioteconomía y Ciencias
de la Información de Web of Science, en el periodo 2007-2017, utilizando la herramienta analítica “Essential Science Indicators”.
Partiendo de los artículos altamente citados, la metodología consistió en la aplicación de análisis de co-palabras así como técnicas
estadísticas de análisis multivariante y visualización a través de un mapa de la ciencia. Los resultados principales mostraron que
las áreas de mayor interés para los investigadores fueron los estudios sobre la Web 2.0 basados en la participación colaborativa
de los usuarios, la evaluación de las actividades científica, las métricas alternativas, o Altmetrics, desarrolladas en las plataformas
sociales y académicas, la seguridad y confianza en los entornos virtuales y, por último, la aplicación de plataformas digitales en
el comercio electrónicoThis paper aims to identify the conceptual structure in the category Library and Information Sciences in the Web of Science, in the period
2007-2017, using the analytical tool Essential Science Indicators. Based on highly cited papers, the methodology consisted in the application
of co-word analysis and multivariate analysis techniques and visualization through science mapping. The main results showed that the
studies on Web 2.0 based on the collaborative participation of the users, the evaluation of scientific activities, as well as the alternative
metrics developed in the social and academic platforms, such as Altmetrics, trust in virtual environments, and the application of information
technologies in companies and digital e-commerce platforms were the areas of greatest interest to the researchers
Search for the standard model Higgs boson in tau final states
We present a search for the standard model Higgs boson using hadronically
decaying tau leptons, in 1 inverse femtobarn of data collected with the D0
detector at the Fermilab Tevatron ppbar collider. We select two final states:
tau plus missing transverse energy and b jets, and tau+ tau- plus jets. These
final states are sensitive to a combination of associated W/Z boson plus Higgs
boson, vector boson fusion and gluon-gluon fusion production processes. The
observed ratio of the combined limit on the Higgs production cross section at
the 95% C.L. to the standard model expectation is 29 for a Higgs boson mass of
115 GeV.Comment: publication versio
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