106 research outputs found

    B0s Oscillation Results

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    We review new studies of the time dependence of B0s - B0s-bar mixing by the ALEPH, DELPHI and SLD Collaborations, with an emphasis on the different analysis methods used. Combining all available results yields a preliminary lower limit on the oscillation frequency of dms > 14.4 ps-1 at the 95% C.L.Comment: 4 pages, 2 figures, contributed to ICHEP2002 proceeding

    Kinematic Evidence of an Embedded Protoplanet in HD 142666 Identified by Machine Learning

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    Observations of protoplanetary disks have shown that forming exoplanets leave characteristic imprints on the gas and dust of the disk. In the gas, these forming exoplanets cause deviations from Keplerian motion, which can be detected through molecular line observations. Our previous work has shown that machine learning can correctly determine if a planet is present in these disks. Using our machine learning models, we identify strong, localized non-Keplerian motion within the disk HD 142666. Subsequent hydrodynamics simulations of a system with a 5 Jupiter-mass planet at 75 au recreates the kinematic structure. By currently established standards in the field, we conclude that HD 142666 hosts a planet. This work represents a first step towards using machine learning to identify previously overlooked non-Keplerian features in protoplanetary disks.Comment: 7 pages, 3 figures, 1 table. Accepted to Ap

    Critical Exponents and Particle Multiplicity Distributions in High Energy Collisions

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    Data from the L3, Tasso, Opal and Delphi collaborations are analyzed in terms of a statistical model of high energy collisions. The model contains a power law critical exponent tau and Levy index alpha. These data are used to study values of tau and alpha. The very high multiplicity events in L3, Opal and Delphi are consistent with a model based on a Feynman-Wilson gas which has a tail exponent tau=3/2 and alpha=1/2.Comment: 10 pages, new table adde

    J/ψJ/\psi suppression in Pb+Pb collisions and pTp_T broadening

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    We have analysed the NA50 data, on the centrality dependence of pTp_T broadening of J/ψJ/\psi's, in Pb+Pb collisions, at the CERN-SPS. The data were analysed in a QCD based model, where J/ψJ/\psi's are suppressed in 'nuclear' medium. Without any free parameter, the model could explain the NA50 pTp_T broadening data. The data were also analysed in a QGP based threshold model, where J/ψJ/\psi suppression is 100% above a critical density. The QGP based model could not explain the NA50 pTp_T broadening data. We have also predicted the centrality dependence of J/ψJ/\psi suppression and pTp_T broadening at RHIC energy. Both the models, the QGP based threshold model and the QCD based nuclear absorption model, predict pTp_T broadening very close to each other.Comment: The paper was completely revised. The conclusion is also changed. 5 pages, 4 figure

    Remarks on Koba-Nielsen-Olesen Scaling

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    It is shown that there is a second properly normalized KNO scaling function, nPn(n/nˉ)=φ(z)nP_n(n/\bar n)=\varphi(z), which has certain advantages in the analysis of KNO scaling. First, the nPnnP_n are not influenced by the statistical and systematic uncertainties of nˉ\bar n hence φ(z)\varphi(z) provides more selective power than the original KNO scaling function nˉPn(n/nˉ)=ψ(z)\bar nP_n(n/\bar n)=\psi(z). Second, the new scaling function generates scale parameter σ=1\sigma=1 since it depends only on the combination of zz and the scale parameter of ψ(z)\psi(z). An analysis of φ(z)\varphi(z) is given using e+ee^+e^- annihilation data for charged particle multiplicity distributions.Comment: 8 pages, Plain TeX, 1 figure using uufile

    Measuring the Photon Helicity in Radiative B Decays

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    We propose a way of measuring the photon polarization in radiative B decays into K resonance states decaying to K\pi\pi, which can test the Standard Model and probe new physics. The photon polarization is shown to be measured by the up-down asymmetry of the photon direction relative to the K\pi\pi decay plane in the K resonance rest frame. The integrated asymmetry in K_1(1400)\to K\pi\pi, calculated to be 0.34\pm 0.05 in the Standard Model, is measurable at currently operating B factories.Comment: 4 pages, final version to appear in Physical Review Letter

    Exclusive semileptonic B decays to radially excited D mesons

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    Exclusive semileptonic B decays to radially excited charmed mesons are investigated at the first order of the heavy quark expansion. The arising leading and subleading Isgur-Wise functions are calculated in the framework of the relativistic quark model. It is found that the 1/m_Q corrections play an important role and substantially modify results. An interesting interplay between different corrections is found. As a result the branching ratio for the B-> D'e\nu decay is essentially increased by 1/m_Q corrections, while the one for B-> D*'e\nu is only slightly influenced by them.Comment: 19 pages, revtex, 6 figures, uses rotating.st
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