470 research outputs found

    Nonfactorization in Hadronic Two-body Cabibbo-favored decays of D^0 and D^+

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    With the inclusion of nonfactorized amplitudes in a scheme with Nc=3N_c=3, we have studied Cabibbo-favored decays of D0D^0 and D+D^+ into two-body hadronic states involving two isospins in the final state. We have shown that it is possible to understand the measured branching ratios and determined the sizes and signs of nonfactorized amplitudes required.Comment: 15 pages, Late

    Two-body Cabibbo-suppressed Decays of Charmed Baryons into Vector Mesons and into Photons

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    The heavy quark effective theory and the factorization approximation are used to treat the Cabibbo-suppressed decays of charmed baryons to vector mesons, ΛCpρ0,pω\Lambda_C\rightarrow p{\rho^0}, p\omega, ΞC+,0Σ+,0ϕ,Σ+,0ρ0,Σ+,0ω\Xi_C^{+,0}\rightarrow\Sigma^{+,0}\phi, \Sigma^{+,0}{\rho^0}, \Sigma^{+,0}\omega and ΞC0Λϕ,Λρ,Λω\Xi_C^{0}\rightarrow\Lambda\phi, \Lambda\rho, \Lambda\omega. The input from two recent experimental results on ΛC\Lambda_C decays allows the estimation of the branching ratios for these modes, which turn out to be between 10410^{-4} and 10310^{-3}. The long distance contribution of these transitions via vector meson dominance to the radiative weak processes ΛCpγ\Lambda_C\rightarrow p\gamma, ΞCΣγ\Xi_C\rightarrow\Sigma\gamma and ΞC0Λγ\Xi_C^0\rightarrow\Lambda\gamma leads to quite small branching ratios, 10610910^{-6}-10^{-9}; the larger value holds if a sum rule between the coupling constants of the vector mesons is broken.Comment: 11 pages, latex, no figure

    Hyperon weak radiative decays in chiral perturbation theory

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    We investigate the leading-order amplitudes for weak radiative decays of hyperons in chiral perturbation theory. We consistently include contributions from the next-to-leading order weak-interaction Lagrangian. It is shown that due to these terms Hara's theorem is violated. The data for the decays of charged hyperons can be easily accounted for. However, at this order in the chiral expansion, the four amplitudes for the decays of neutral hyperons satisfy relations which are in disagreement with the data. The asymmetry parameters for all the decays can not be accounted for without higher-order terms. We shortly comment on the effect of the 27-plet part of the weak interaction.Comment: 8 pages of REVTeX and using macro-package "feynman.tex" (available at http://xxx.lanl.gov/ftp/hep-ph/papers/macros) for the 2 figure

    Dynamics of coherently pumped lasers with linearly polarized pump and generated fields

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    The influence of light polarization on the dynamics of an optically pumped single-mode laser with a homogeneously broadened four-level medium is theoretically investigated in detail. Pump and laser fields with either parallel or crossed linear polarizations are considered, as are typical in far-infrared-laser experiments. Numerical simulations reveal dramatically different dynamic behaviors for these two polarization configurations. The analysis of the model equations allows us to find the physical origin of both behaviors. In particular, the crossed-polarization configuration is shown to be effective in decoupling the pump and laser fields, thus allowing for the appearance of Lorenz-type dynamics

    Study of the decay asymmetry parameter and CP violation parameter in the Lambdac+ --> Lambda pi+ decay

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    Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement of the weak decay-asymmetry parameter alpha(Lambdac) in Lambdac --> Lambda pi decay. Comparing particle with antiparticle decays, we obtain the first measurement of the CP violation parameter : A = [alpha(Lambdac)+alpha(antiLambda_c)]/[alpha(Lambdac)-alpha(antiLambda_c)]. We obtain alpha(Lambdac)=-0.78+-0.16+-0.13 and A = -0.07+-0.19+-0.12 where errors are statistical and systematic.Comment: 18 pages, to be submitted to Phys. Lett. B For a list of the FOCUS collaboration, see http://www-focus.fnal.gov/authors.htm

    A Measurement of the Decay Asymmetry Parameters in \Xi_{c}^{0}\to \X^{-}\pi^{+}

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    Using the CLEO II detector at the Cornell Electron Storage Ring we have measured the Ξc0\Xi_c^{0} decay asymmetry parameter in the decay Ξc0Ξπ+\Xi_c^{0} \to \Xi^{-} \pi^+. We find αΞc0αΞ=0.26±0.18(stat)0.04+0.05(syst)\alpha_{\Xi_c^{0}} \alpha_{\Xi} = 0.26 \pm 0.18{(stat)}^{+0.05}_{-0.04}{(syst)}, using the world average value of αΞ=0.456±0.014\alpha_{\Xi} = -0.456 \pm 0.014 we obtain αΞc0=0.56±0.39(stat)0.09+0.10(syst)\alpha_{\Xi_c^{0}} = -0.56 \pm 0.39{(stat)}^{+0.10}_{-0.09}{(syst)}. The physically allowed range of a decay asymmetry parameter is 1<α<+1-1<\alpha<+1. Our result prefers a negative value: αΞc0\alpha_{\Xi_c^{0}} is <0.1<0.1 at the 90% CL. The central value occupies the middle of the theoretically expected range but is not yet precise enough to choose between models.Comment: 10 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

    Intelligent intrusion detection system in smart grid using computational intelligence and machine learning

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    Smart grid systems enhanced the capability of traditional power networks while being vulnerable to different types of cyber-attacks. These vulnerabilities could cause attackers to crash into the network breaching the integrity and confidentiality of the smart grid systems. Therefore, an intrusion detection system (IDS) becomes an important way to provide a secure and reliable services in a smart grid environment. This article proposes a feature-based IDS for smart grid systems. The proposed system performance is evaluated in terms of accuracy, intrusion detection rate (DR), and false alarm rate (FAR). The obtained results show that the random forest and neural network classifiers have outperformed other classifiers. We have achieved a 0.5% FAR on KDD99 dataset and a 0.08% FAR on the NSLKDD dataset. The DR and the testing accuracy on average are 99% for both datasets

    Gastric Juvenile Polyposis with High-Grade Dysplasia in Pachydermoperiostosis

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    Pachydermoperiostosis (PDP) is the primary form of hypertrophic osteoarthropathy. It is a very rare disease consisting of pachydermia, digital clubbing and radiologic periostosis. Various digestive symptoms in PDP are seen in 11–49% of patients and juvenile polyps may be found at gastric endoscopy. We report here the history of a patient with PDP who was referred for assessment of severe anemia. Endoscopy of the upper digestive tract showed multiple polyps of the stomach with two huge lesions exhibiting foci of high-grade dysplasia. This observation suggests that PDP can be considered as a precancerous condition of the stomach and systematic screening using endoscopy should be considered in these patients

    The forgotten smoker: a qualitative study of attitudes towards smoking, quitting, and tobacco control policies among continuing smokers

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    Although research suggests that the majority of smokers want to quit smoking, the uptake of Stop Smoking Services, designed to assist smokers with quitting, remains low. Little is known about continuing smokers who do not access these services, and opportunities to influence their motivation and encourage quit attempts through the uptake of services. Using PRIME theory, this study explored differences between continuing smokers who had varying levels of motivation to quit, in terms of their plans to quit, evaluative beliefs about smoking, cigarette dependence, and attitudes towards tobacco control policies and services
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