1,082 research outputs found

    Eta-meson production in the resonance energy region

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    We perform an updated coupled-channel analysis of eta-meson production including all recent photoproduction data on the proton. The dip observed in the differential cross sections at c.m. energies W=1.68 GeV is explained by destructive interference between the S11(1535)S_{11}(1535) and S11(1560)S_{11}(1560) states. The effect from P11(1710)P_{11}(1710) is found to be small but still important to reproduce the correct shape of the differential cross section. For the πNηN\pi^- N \to \eta N scattering we suggest a reaction mechanism in terms of the S11(1535)S_{11}(1535), S11(1560)S_{11}(1560), and P11(1710)P_{11}(1710) states. Our conclusion on the importance of the S11(1535)S_{11}(1535), S11(1560)S_{11}(1560), and P11(1710)P_{11}(1710) resonances in the eta-production reactions is in line with our previous results. No strong indication for a narrow state with a width of 15 MeV and the mass of 1680 MeV is found in the analysis. ηN\eta N scattering length is extracted and discussed.Comment: replaced with a published version, pole parameters and scattering lengths are adde

    The Symmetries of Nature

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    The study of the symmetries of nature has fascinated scientists for eons. The application of the formal mathematical description of symmetries during the last century has produced many breakthroughs in our understanding of the substructure of matter. In this talk, a number of these advances are discussed, and the important role that George Sudarshan played in their development is emphasize

    Analysis of electroencephalograms in Alzheimer's disease patients with multiscale entropy

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    The aim of this study was to analyse the electroencephalogram (EEG) background activity of Alzheimer’s disease (AD) patients using the Multiscale Entropy (MSE). The MSE is a recently developed method that quantifies the regularity of a signal on different time scales. These time scales are inspected by means of several coarse-grained sequences formed from the analysed signals. We recorded the EEGs from 19 scalp electrodes in 11 AD patients and 11 age-matched controls and estimated the MSE profile for each epoch of the EEG recordings. The shape of the MSE profiles reveals the EEG complexity, and it suggests that the EEG contains information in deeper scales than the smallest one. Moreover, the results showed that the EEG background activity is less complex in AD patients than control subjects. We found significant difference

    Reply to "Comment on 'Analysis of electroencephalograms in Alzheimer's disease patients with multiscale entropy'"

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    We appreciate the interest of Dr Tang in our article. Certainly, our previous results should be taken with caution due to the small database size. Nevertheless, it must be noted that this limitation was clearly recognized in our article. Furthermore, our hypothesis is completely justified from the current state of the art in the analysis of electroencephalogram (EEG) signals from Alzheimer's disease (AD) patients. We evaluated whether the multiscale entropy (MSE) analysis of the EEG background activity was useful to distinguish AD patients and controls. We do believe that further discussions about risk factors or related clinicophysiological protein aspects are clearly beyond the scope of our article. For the sake of completeness, we now detail some results that complement our previous analysis. They suggest that the MSE analysis can provide relevant information about the dynamics of AD patients' EEG data. Thus, we must reaffirm our conclusions, although we again acknowledge that further studies are needed

    On Muddled Methods and Their Meaning

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68431/2/10.1177_048661346900100105.pd

    Strangeness Content in the Nucleon

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    I review recent studies of strangeness content in the nucleon pertaining to the flavor-singlet gA0g_A^0, the sˉs\bar{s}s matrix element and the strangeness electric and magnetic form factors GEs(q2)G_E^s(q^2) and GMs(q2)G_M^s(q^2), based on lattice QCD calculations. I shall also discuss the relevance of incorporating the strangeness content in nuclei in regard to strange baryon-antibaryon productions from proton-nucleus and nucleus-nucleus collisions at SPS and RHIC energies.Comment: 11 pages, 4 figures, Invited talk at V Int. Conf. on Strangeness in Quark Matter, Berkeley, CA, July 20--25, 200

    Phi meson production in In-In collisions at ElabE_{\rm lab}=158AA GeV: evidence for relics of a thermal phase

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    Yields and transverse mass distributions of the ϕ\phi-mesons reconstructed in the ϕμ+μ\phi\to\mu^+\mu^- channel in In+In collisions at ElabE_{\rm lab}=158AA GeV are calculated within an integrated Boltzmann+hydrodynamics hybrid approach based on the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) transport model with an intermediate hydrodynamic stage. The analysis is performed for various centralities and a comparison with the corresponding NA60 data in the muon channel is presented. We find that the hybrid model, that embeds an intermediate locally equilibrated phase subsequently mapped into the transport dynamics according to thermal phase-space distributions, gives a good description of the experimental data, both in yield and slope. On the contrary, the pure transport model calculations tend to fail in catching the general properties of the ϕ\phi meson production: not only the yield, but also the slope of the mTm_T spectra, very poorly compare with the experimental observations

    Changing distribution of the east coast of Scotland bottlenose dolphin population and the challenges of area‐based management

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    MAC received funding from the Department of Energy and Climate Change (DECC) (now Department for Business, Energy and Industrial Strategy) UK, and the MASTS (Marine Alliance for Science and Technology for Scotland) pooling initiative. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. Annual surveys were funded by DECC, Scottish Natural Heritage (SNH), Beatrice Offshore Windfarm Ltd., Moray Offshore Renewables Ltd, Marine Scotland, The Crown Estate, Highlands and Islands Enterprise and the Universities of St Andrews and Aberdeen. All fieldwork was carried out under SNH Animal Scientific Licences to PMT and PSH. The authors have no conflict of interest to declare. We thank John Baxter for helpful discussions about the implications for conservation and management while drafting this manuscript, and Morven Carruthers for her advice on the site condition monitoring for the Moray Firth SAC. This manuscript benefited from the helpful comments of two anonymous reviewers.Peer reviewedPostprin

    Quark-model study of few-baryon systems

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    We review the application of non-relativistic constituent quark models to study one, two and three non-strange baryon systems. We present results for the baryon spectra, potentials and observables of the NN, NΔ\Delta, ΔΔ\Delta\Delta and NN(1440)^*(1440) systems, and also for the binding energies of three non-strange baryon systems. We make emphasis on observable effects related to quark antisymmetry and its interplay with quark dynamics.Comment: 82 pages, 36 figures, 18 tables. Accepted for publication in Reports on Progress in Physic

    History of exotic Meson (4-quark) and Baryon (5-quark) States

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    I briefly review the history of exotic meson (4-quark) and baryon (5-quark) states, which is rooted in the formalism of Regge pole and duality. There are robust model-independent predictions for the exchange of 4-quark (Baryonium) Regge trajectories in several processes, which are strongly supported by experiment. On the other hand the predictions for the spectroscopy of 4-quark resonances are based on specific QCD inspired models, with some experimental support. The corresponding predictions for the recently discovered exotic baryon (Pentaquark) state are briefly discussed.Comment: 14 pages Latex including 4 eps figures, final version to appear as a topical review in J. Phys.
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