RESUMO
High precision measurements of the differential cross sections for π0 photoproduction at forward angles for two nuclei, 12C and 208Pb, have been performed for incident photon energies of 4.9-5.5 GeV to extract the π0âγγ decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The π0âγγ decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is Γ(π0âγγ)=7.82±0.14(stat)±0.17(syst) eV. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current Particle Data Group average of this fundamental quantity, and it is consistent with current theoretical predictions.
RESUMO
The article presents the case of ischemic stroke with enough favorable outcome in the patient of 19 y.o. The cause of this stroke was determined. It was "a web" of numerous anomalous located chords in the apical part of left ventricle.
Assuntos
Isquemia Encefálica/etiologia , Ventrículos do Coração/anatomia & histologia , Infarto da Artéria Cerebral Média/etiologia , Disfunção Ventricular Esquerda/complicações , Adulto , Isquemia Encefálica/fisiopatologia , Isquemia Encefálica/terapia , Circulação Cerebrovascular/fisiologia , Ecocardiografia Doppler , Eletrocardiografia , Escala de Coma de Glasgow , Ventrículos do Coração/diagnóstico por imagem , Hemiplegia/etiologia , Hemiplegia/fisiopatologia , Hemiplegia/terapia , Humanos , Infarto da Artéria Cerebral Média/fisiopatologia , Infarto da Artéria Cerebral Média/terapia , Masculino , Tomografia Computadorizada por Raios X , Disfunção Ventricular Esquerda/diagnóstico por imagemRESUMO
We observe a signal for the doubly charmed baryon Xi(+)(cc) in the charged decay mode Xi(+)(cc)-->Lambda(+)(c)K-pi(+) in data from SELEX, the charm hadroproduction experiment at Fermilab. We observe an excess of 15.9 events over an expected background of 6.1+/-0.5 events, a statistical significance of 6.3sigma. The observed mass of this state is 3519+/-1 MeV/c(2). The Gaussian mass width of this state is 3 MeV/c(2), consistent with resolution; its lifetime is less than 33 fs at 90% confidence.
RESUMO
We report the first observation of a charm-strange meson D(+)(sJ)(2632) at a mass of 2632.5+/-1.7 MeV/c(2) in data from SELEX, the charm hadro-production experiment E781 at Fermilab. This state is seen in two decay modes, D(+)(s)eta and D0K+. In the D(+)(s)eta decay mode we observe a peak with 101 events over a combinatoric background of 54.9 events at a mass of 2635.4+/-3.3 MeV/c(2). There is a corresponding peak of 21 events over a background of 6.9 at 2631.5+/-2.0 MeV/c(2) in the decay mode D0K+. The decay width of this state is <17 MeV/c(2) at 90% confidence level. The relative branching ratio Gamma(D0K+)/Gamma(D(+)(s)eta) is 0.14+/-0.06. The mechanism that keeps this state narrow is unclear. Its decay pattern is also unusual, being dominated by the D(+)(s)eta decay mode.
RESUMO
We report new precision measurements of the lifetimes of the Lambda(+)(c) and D0 from SELEX, the charm hadroproduction experiment at Fermilab. Based upon 1630 Lambda(+)(c) and 10 210 D0 decays we observe lifetimes of tau[Lambda(+)(c)] = 198.1+/-7.0+/-5.6 fs and tau[D0] = 407.9+/-6.0+/-4.3 fs.
RESUMO
We report the first observation of the Cabibbo-suppressed charm baryon decay Ξ_{c}^{+}âpK^{-}π^{+}. We observe 150±22±5 events for the signal. The data were accumulated using the SELEX spectrometer during the 1996-1997 fixed target run at Fermilab, chiefly from a 600 GeV/c Σ^{-} beam. The branching fractions of the decay relative to the Cabibbo-favored Ξ_{c}^{+}âΣ^{+}K^{-}π^{+} and Ξ_{c}^{+}âΞ^{-}π^{+}π^{+} are measured to be B(Ξ_{c}^{+}âpK^{-}π^{+})/B(Ξ_{c}^{+}âΣ^{+}K^{-}π^{+})=0.22±0.06±0.03 and B(Ξ_{c}^{+}âpK^{-}π^{+})/B(Ξ_{c}^{+}âΞ^{-}π^{+}π^{+})=0.20±0.04±0.02, respectively.