227 research outputs found

    Reducing theoretical uncertainties in mb and lambda1

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    We calculate general moments of the lepton energy spectrum in inclusive semileptonic B -> X_c l \nu decay. Moments which allow the determination of mb^{1S} and lambda1 with theoretical uncertainties Delta(mb^{1S}) ~ 0.04 GeV and Delta(lambda1) ~ 0.05 GeV^2 are presented. The short distance 1S mass is used to extract a mass parameter free of renormalon ambiguities. Moments which are insensitive to mb and lambda1 and therefore test the size of the 1/mb^3 matrix elements and the validity of the OPE are also presented. Finally, we give an expression for the total branching ratio with a lower cut on the lepton energy, which allows one to eliminate a source of model dependence in current determinations of |Vcb| from B -> X_c l \nu decay.Comment: 8 pages, one figur

    The Isgur-Wise function in a relativistic model for qQˉq\bar Q system

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    We use the Dirac equation with a ``(asymptotically free) Coulomb + (Lorentz scalar) linear '' potential to estimate the light quark wavefunction for qQˉ q\bar Q mesons in the limit mQm_Q\to \infty. We use these wavefunctions to calculate the Isgur-Wise function ξ(v.v)\xi (v.v^\prime ) for orbital and radial ground states in the phenomenologically interesting range 1v.v41\leq v.v^ \prime \leq 4. We find a simple expression for the zero-recoil slope, ξ(1)=1/2ϵ2/3\xi^ \prime (1) =-1/2- \epsilon^2 /3, where ϵ\epsilon is the energy eigenvalue of the light quark, which can be identified with the Λˉ\bar\Lambda parameter of the Heavy Quark Effective Theory. This result implies an upper bound of 1/2-1/2 for the slope ξ(1)\xi^\prime (1). Also, because for a very light quark q(q=u,d)q (q=u, d) the size \sqrt {} of the meson is determined mainly by the ``confining'' term in the potential (γσr)(\gamma_\circ \sigma r), the shape of ξu,d(v.v)\xi_{u,d}(v.v^\prime ) is seen to be mostly sensitive to the dimensionless ratio Λˉu,d2/σ\bar \Lambda_{u,d}^2/\sigma. We present results for the ranges of parameters 150MeV<Λˉu,d<600MeV150 MeV <\bar \Lambda_{u,d} <600 MeV (ΛˉsΛˉu,d+100MeV)(\bar\Lambda_s \approx \bar\Lambda_{u,d}+100 MeV), 0.14GeV2σ0.25GeV20.14 {GeV}^2 \leq \sigma \leq 0.25 {GeV}^2 and light quark masses mu,md0,ms=175MeVm_u, m_d \approx 0, m_s=175 MeV and compare to existing experimental data and other theoretical estimates. Fits to the data give: Λˉu,d2/σ=4.8±1.7{\bar\Lambda_{u,d}}^2/\sigma =4.8\pm 1.7 , ξu,d(1)=2.4±0.7-\xi^\prime_{u,d}(1)=2.4\pm 0.7 and VcbτB1.48ps=0.050±0.008\vert V_{cb} \vert \sqrt {\frac {\tau_B}{1.48 ps}}=0.050\pm 0.008 [ARGUS '93]; Λˉu,d2/σ=3.4±1.8{\bar\Lambda_{u,d}}^2/\sigma = 3.4\pm 1.8, ξu,d(1)=1.8±0.7-\xi^\prime_{u,d}(1)=1.8\pm 0.7 and VcbτB1.48ps=0.043±0.008\vert V_{cb} \vert \sqrt { \frac {\tau_B}{1.48 ps}}=0.043\pm 0.008 [CLEO '93]; ${\bar\Lambda_{u,d}}^2/Comment: 22 pages, Latex, 4 figures (not included) available by fax or via email upon reques

    Status of a hybrid three-neutrino interpretation of neutrino data

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    We reanalyze the non-standard interaction (NSI) solutions to the solar neutrino problem in the light of the latest solar, atmospheric and reactor neutrino data. We show that such solutions, although preferred by the solar data and consistent with the oscillation description of the atmospheric neutrino data, are ruled out by the first results of the KamLAND reactor experiment, at more than 3_sigma.Comment: 19 pages, LaTeX file using Elsart, 2 tables and 4 figures included. This version updates the one published in Nucl.Phys.B629:479-490,2002 by including the new KamLAND dat

    Study of the B^0 Semileptonic Decay Spectrum at the Upsilon(4S) Resonance

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    We have made a first measurement of the lepton momentum spectrum in a sample of events enriched in neutral B's through a partial reconstruction of B0 --> D*- l+ nu. This spectrum, measured with 2.38 fb**-1 of data collected at the Upsilon(4S) resonance by the CLEO II detector, is compared directly to the inclusive lepton spectrum from all Upsilon(4S) events in the same data set. These two spectra are consistent with having the same shape above 1.5 GeV/c. From the two spectra and two other CLEO measurements, we obtain the B0 and B+ semileptonic branching fractions, b0 and b+, their ratio, and the production ratio f+-/f00 of B+ and B0 pairs at the Upsilon(4S). We report b+/b0=0.950 (+0.117-0.080) +- 0.091, b0 = (10.78 +- 0.60 +- 0.69)%, and b+ = (10.25 +- 0.57 +- 0.65)%. b+/b0 is equivalent to the ratio of charged to neutral B lifetimes, tau+/tau0.Comment: 14 page, postscript file also available at http://w4.lns.cornell.edu/public/CLN

    Measurement of the B-Meson Inclusive Semileptonic Branching Fraction and Electron-Energy Moments

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    We report a new measurement of the B-meson semileptonic decay momentum spectrum that has been made with a sample of 9.4/fb of electron-positron annihilation data collected with the CLEO II detector at the Y(4S) resonance. Electrons from primary semileptonic decays and secondary charm decays were separated by using charge and angular correlations in Y(4S) events with a high-momentum lepton and an additional electron. We determined the semileptonic branching fraction to be (10.91 +- 0.09 +- 0.24)% from the normalization of the electron-energy spectrum. We also measured the moments of the electron energy spectrum with minimum energies from 0.6 GeV to 1.5 GeV.Comment: 36 pages postscript, als available through http://w4.lns.cornell.edu/public/CLNS/, Submitted to PRD (back-to-back with preceding preprint hep-ex/0403052

    Detector Description and Performance for the First Coincidence Observations between LIGO and GEO

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    For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data.Comment: 41 pages, 9 figures 17 Sept 03: author list amended, minor editorial change

    Leptonic and Semileptonic Decays of Charm and Bottom Hadrons

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    We review the experimental measurements and theoretical descriptions of leptonic and semileptonic decays of particles containing a single heavy quark, either charm or bottom. Measurements of bottom semileptonic decays are used to determine the magnitudes of two fundamental parameters of the standard model, the Cabibbo-Kobayashi-Maskawa matrix elements VcbV_{cb} and VubV_{ub}. These parameters are connected with the physics of quark flavor and mass, and they have important implications for the breakdown of CP symmetry. To extract precise values of Vcb|V_{cb}| and Vub|V_{ub}| from measurements, however, requires a good understanding of the decay dynamics. Measurements of both charm and bottom decay distributions provide information on the interactions governing these processes. The underlying weak transition in each case is relatively simple, but the strong interactions that bind the quarks into hadrons introduce complications. We also discuss new theoretical approaches, especially heavy-quark effective theory and lattice QCD, which are providing insights and predictions now being tested by experiment. An international effort at many laboratories will rapidly advance knowledge of this physics during the next decade.Comment: This review article will be published in Reviews of Modern Physics in the fall, 1995. This file contains only the abstract and the table of contents. The full 168-page document including 47 figures is available at http://charm.physics.ucsb.edu/papers/slrevtex.p

    Proximity effect at superconducting Sn-Bi2Se3 interface

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    We have investigated the conductance spectra of Sn-Bi2Se3 interface junctions down to 250 mK and in different magnetic fields. A number of conductance anomalies were observed below the superconducting transition temperature of Sn, including a small gap different from that of Sn, and a zero-bias conductance peak growing up at lower temperatures. We discussed the possible origins of the smaller gap and the zero-bias conductance peak. These phenomena support that a proximity-effect-induced chiral superconducting phase is formed at the interface between the superconducting Sn and the strong spin-orbit coupling material Bi2Se3.Comment: 7 pages, 8 figure

    Heavy Quarks and Heavy Quarkonia as Tests of Thermalization

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    We present here a brief summary of new results on heavy quarks and heavy quarkonia from the PHENIX experiment as presented at the "Quark Gluon Plasma Thermalization" Workshop in Vienna, Austria in August 2005, directly following the International Quark Matter Conference in Hungary.Comment: 8 pages, 5 figures, Quark Gluon Plasma Thermalization Workshop (Vienna August 2005) Proceeding

    Single Electrons from Heavy Flavor Decays in p+p Collisions at sqrt(s) = 200 GeV

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    The invariant differential cross section for inclusive electron production in p+p collisions at sqrt(s) = 200 GeV has been measured by the PHENIX experiment at the Relativistic Heavy Ion Collider over the transverse momentum range $0.4 <= p_T <= 5.0 GeV/c at midrapidity (eta <= 0.35). The contribution to the inclusive electron spectrum from semileptonic decays of hadrons carrying heavy flavor, i.e. charm quarks or, at high p_T, bottom quarks, is determined via three independent methods. The resulting electron spectrum from heavy flavor decays is compared to recent leading and next-to-leading order perturbative QCD calculations. The total cross section of charm quark-antiquark pair production is determined as sigma_(c c^bar) = 0.92 +/- 0.15 (stat.) +- 0.54 (sys.) mb.Comment: 329 authors, 6 pages text, 3 figures. Submitted to Phys. Rev. Lett. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm
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