409 research outputs found
Factorization and Nonfactorization in B Decays
Using NLL values for Wilson coefficients and including the contributions from
the penguin diagrams, we estimate the amount of nonfactorization in two-body
hadronic B decays. Also, we investigate the model dependence of the
nonfactorization parameters by performing the calculation using different
models for the form factors. The results support the universality of
nonfactorizable contributions in both Cabibbo-favored and Cabibbo-suppressed B
decays.Comment: 17 pages, 5 figures, revte
Updated Analysis of a_1 and a_2 in Hadronic Two-body Decays of B Mesons
Using the recent experimental data of , , and various model calculations on form
factors, we re-analyze the effective coefficients a_1 and a_2 and their ratio.
QCD and electroweak penguin corrections to a_1 from and
a_2 from are estimated. In addition to the
model-dependent determination, the effective coefficient a_1 is also extracted
in a model-independent way as the decay modes are related by
factorization to the measured semileptonic distribution of at . Moreover, this enables us to extract model-independent
heavy-to-heavy form factors, for example,
and
. The determination of the magnitude of
a_2 from depends on the form factors ,
and at . By requiring that a_2 be
process insensitive (i.e., the value of a_2 extracted from and
states should be similar), as implied by the factorization
hypothesis, we find that form factors are severely constrained;
they respect the relation . Form factors and at
inferred from the measurements of the longitudinal
polarization fraction and the P-wave component in are
obtained. A stringent upper limit on a_2 is derived from the current bound on
\ov B^0\to D^0\pi^0 and it is sensitive to final-state interactions.Comment: 33 pages, 2 figures. Typos in Tables I and IX are corrected. To
appear in Phys. Rev.
Test of CPT Symmetry and Quantum Mechanics with Experimental data from CPLEAR
We use fits to recent published CPLEAR data on neutral kaon decays to
and to constrain the CPT--violation parameters
appearing in a formulation of the neutral kaon system as an open
quantum-mechanical system. The obtained upper limits of the CPT--violation
parameters are approaching the range suggested by certain ideas concerning
quantum gravity.Comment: 9 pages of uuencoded postscript (includes 3 figures
Vasodilator activity of extracts of field Alpinia purpurata (Vieill) K: Schum and A. zerumbet (Pers.) Burtt et Smith cultured in vitro
Nowadays, the high blood pressure is one of the main causes of death and cardiovascular diseases. Vasodilator drugs are frequently used to treat arterial hypertension. Experiments were undertaken to determine whether hydroalcoholic extracts obtained from leaves of field-grown Alpinia purpurata and A. zerumbet cultured in vitro under different plant growth regulators induce a vasodilator effect on Wistar rat mesenteric vascular bed pre-contracted with norepinephrine. Plant extracts were able to induce a long-lasting endothelium-dependent vasodilation. Efficiency on activity of A. purpurata reached 87% at concentration of 60 μg. The extract of A. zerumbet maintained in medium containing IAA, induced the relaxation (17.4%) at 90 μg, as compared to the control (MS0) that showed a better vasodilator effect (60%). These results are in agreement with the quantification of phenolic compounds in the extracts, which were 50% lower for those plants cultured in IAA. A. purpurata was assayed for the first time in relation to its vasodilator activity. This paper showed a strong probability of correlation between the pharmacological activities of A. purpurata with their content in phenolic compounds.Atualmente, a hipertensĂŁo arterial Ă© uma das maiores causas de morte e de doenças cardiovasculares. Os vasodilatadores sĂŁo freqĂŒentemente utilizados no tratamento da hipertensĂŁo. Extratos hidroalcoĂłlicos de Alpinia purpurata de campo e de A. zerumbet cultivada in vitro sob diferentes reguladores de crescimento vegetal foram ensaiados no leito mesentĂ©rico de ratos Wistar. Os extratos de A. purpurata e A. zerumbet produziram efeito vasodilatador com padrĂŁo de resposta dose-dependente de duração prolongada. Extratos da espĂ©cie A. purpurata tiveram efeito vasodilatador de 87% na dose de 60 μg. O extrato obtido de folhas de A. zerumbet oriundas das culturas mantidas em meio contendo AIA (ĂĄcido indol acĂ©tico) inibiu o relaxamento (17,4%) na dose de 90 μg em relação ao controle (MS0), com o qual foi verificado melhor efeito vasodilatador (60%). Estes resultados estĂŁo de acordo com a concentração de fenĂłis totais que foi 50% menor para os extratos de plantas cultivadas in vitro em AIA. A espĂ©cie A. purpurata foi pela primeira vez ensaiada quanto Ă atividade vasodilatadora. Os resultados obtidos indicaram a presença de substĂąncias fenĂłlicas provavelmente correlacionadas Ă ação terapĂȘutica de A. purpurata
Vaccinia Virus Infection in Monkeys, Brazilian Amazon
To detect orthopoxvirus in the Brazilian Amazon, we conducted a serosurvey of 344 wild animals. Neutralizing antibodies against orthopoxvirus were detected by plaque-reduction neutralizing tests in 84 serum samples. Amplicons from 6 monkey samples were sequenced. These amplicons identified vaccinia virus genetically similar to strains from bovine vaccinia outbreaks in Brazil
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
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