7,877 research outputs found

    Time Reversal Violation from the entangled B0-antiB0 system

    Full text link
    We discuss the concepts and methodology to implement an experiment probing directly Time Reversal (T) non-invariance, without any experimental connection to CP violation, by the exchange of "in" and "out" states. The idea relies on the B0-antiB0 entanglement and decay time information available at B factories. The flavor or CP tag of the state of the still living neutral meson by the first decay of its orthogonal partner overcomes the problem of irreversibility for unstable systems, which prevents direct tests of T with incoherent particle states. T violation in the time evolution between the two decays means experimentally a difference between the intensities for the time-ordered (l^+ X, J/psi K_S) and (J/psi K_L, l^- X) decays, and three other independent asymmetries. The proposed strategy has been applied to simulated data samples of similar size and features to those currently available, from which we estimate the significance of the expected discovery to reach many standard deviations.Comment: 17 pages, 2 figures, 6 table

    Eddy current effects in plain and hollow cylinders spinning inside homogeneous magnetic fields: Application to magnetic resonance

    Get PDF
    International audienceWe present a thorough analysis of eddy currents that develop in a rectangular cross section toroid rotating in a uniform magnetic field. The slow rotation regime is assumed. Compact expressions for the current density, the total dissipated power, and the braking torque are given. Examination of the topology of current lines reveals that depending upon the relative dimensions of the side and length of the toroid two different regimes exist. The conditions of existence of the two regimes are analytically established. In view of nuclear magnetic resonance (NMR) applications, we derive the angular variation of the magnetic field created by eddy currents and lay down the formalism necessary for calculating the effect of this field on the NMR spectra of the conductor itself or of a sample co-rotating with the conductor, a situation encountered when dealing with rotating detectors. Examples of calculations for cases of practical interest are presented. The theory is confronted with available data, and we give guidelines for the design of optimized rotating micro-coils

    Facteurs de localisation de l'emploi résidentiel en France

    Get PDF
    Cette communication a pour objectif d'analyser la distribution spatiale des activités de services destinés à la population ainsi que les facteurs d'hétérogénéité spatiale de la densité des emplois relevant de ces secteurs, examinée à l'échelle des bassins de vie. Deux grandes catégories de facteurs explicatifs sont examinées en mobilisant des méthodes statistiques : l'effet du potentiel de marché et la propension à consommer localement. L'estimation des emplois relevant du tourisme permet de prendre en compte la dynamique des services attachée à l'attractivité et à l'équipement des différents espaces. La communication débouche, d'une part, sur l'identification des facteurs structurels relevant de la demande locale et, d'autre part, sur la mise en évidence des configurations territoriales les plus propices au développement de l'emploi résidentiel.ECONOMIE;ANALYSE STATISTIQUE;EMPLOI;ECONOMIE RESIDENTIELLE;FACTEUR DE LOCALISATION

    Inclusive Λ_c^+ production in e^+e^- annihilations at √s=10.54  GeV and in ΄(4S) decays

    Get PDF
    We present measurements of the total production rates and momentum distributions of the charmed baryon Λ_c^+ in e^+e^-→hadrons at a center-of-mass energy of 10.54 GeV and in ΄(4S) decays. In hadronic events at 10.54 GeV, charmed hadrons are almost exclusively leading particles in e^+e^-→cc[overbar] events, allowing direct studies of c-quark fragmentation. We measure a momentum distribution for Λ_c^+ baryons that differs significantly from those measured previously for charmed mesons. Comparing with a number of models, we find none that can describe the distribution completely. We measure an average scaled momentum of =0.574±0.009 and a total rate of N_(Λc)^(qq[overbar]) =0.057±0.002(exp)±0.015(BF)  Λ_c^+ per hadronic event, where the experimental error is much smaller than that due to the branching fraction into the reconstructed decay mode, pK^-π^+. In ΄(4S) decays we measure a total rate of N_(Λc)^΄=0.091±0.006(exp)±0.024(BF) per ΄(4S) decay, and find a much softer momentum distribution than expected from B decays into a Λ_c^+ plus an antinucleon and one to three pions

    Measurement of branching fractions and CP-violating charge asymmetries for B-meson decays to D^(*)D^(*), and implications for the Cabibbo-Kobayashi-Maskawa angle Îł

    Get PDF
    We present measurements of the branching fractions and charge asymmetries of B decays to all D^(*)D^(*) modes. Using 232×10^6 BB pairs recorded on the ΄(4S) resonance by the BABAR detector at the e^+e^- asymmetric B factory PEP-II at the Stanford Linear Accelerator Center, we measure the branching fractions B(B^0→D^(*+)D^(*-))=(8.1±0.6±1.0)×10^(-4), B(B^0→D^(*±)D^∓)=(5.7±0.7±0.7)×10^(-4), B(B^0→D^+D^-)=(2.8±0.4±0.5)×10^(-4), B(B^+→D^(*+)D^(*0))=(8.1±1.2±1.2)×10^(-4), B(B^+→D^*+D^0)=(3.6±0.5±0.4)×10^(-4), B(B^+→D^+D^(*0))=(6.3±1.4±1.0)×10^(-4), and B(B^+→D^+D^(0))=(3.8±0.6±0.5)×10^(-4), where in each case the first uncertainty is statistical and the second systematic. We also determine the limits B(B^0→D^(*0)D^(*0))<0.9×10^(-4), B(B^0→D^(*0)D^0)<2.9×10^(-4), and B(B^0→D^0D^0)<0.6×10^(-4), each at 90% confidence level. All decays above denote either member of a charge-conjugate pair. We also determine the CP-violating charge asymmetries A(B^0→D^(*±)D^∓)=0.03±0.10±0.02, A(B^+→D^(*+)D^(*0))=-0.15±0.11±0.02, A(B^+→D^(*+)D^0)=-0.06±0.13±0.02, A(B^+→D^+D^(*0))=0.13±0.18±0.04, and A(B^+→D^+D^0)=-0.13±0.14±0.02. Additionally, when we combine these results with information from time-dependent CP asymmetries in B^0→D^((*)+)D^((*)-) decays and world-averaged branching fractions of B decays to D_s^(*)D^(*) modes, we find the Cabibbo-Kobayashi-Maskawa phase Îł is favored to lie in the range (0.07–2.77) radians (with a +0 or +π radians ambiguity) at 68% confidence level

    Search for the decay τ-→3π^-2π^+2π^0Îœ_τ

    Get PDF
    A search for the decay of the τ lepton to five charged and two neutral pions is performed using data collected by the BABAR detector at the PEP-II asymmetric-energy e^+e^- collider. The analysis uses 232  fb^(-1) of data at center-of-mass energies on or near the ΄(4S) resonance. We observe 10 events with an expected background of 6.5_(-1.4)^(+2.0) events. In the absence of a signal, we set the limit on the branching ratio B(τ-→3π^-2π^+2π^0Îœ_τ)<3.4×10^(-6) at the 90% confidence level. This is a significant improvement over the previously established limit. In addition, we search for the decay mode τ-→2ωπ-Îœ_τ. We observe 1 event with an expected background of 0.4+1.0/-0.4 events and calculate the upper limit B(τ-→2ωπ-Îœ_τ)<5.4×10^(-7) at the 90% confidence level. This is the first upper limit for this mode

    Study of the decay B^0→D^(*+)ωπ^-

    Get PDF
    We report on a study of the decay B^0→D^(*+)ωπ^- with the BABAR detector at the PEP-II B-factory at the Stanford Linear Accelerator Center. Based on a sample of 232×10^6 BB decays, we measure the branching fraction B(B^0→D^(*+)ωπ^-)=(2.88±0.21(stat.)±0.31(syst.))×10^(-3). We study the invariant mass spectrum of the ωπ^- system in this decay. This spectrum is in good agreement with expectations based on factorization and the measured spectrum in τ-→ωπ-Îœ_τ. We also measure the polarization of the D^(*+) as a function of the ωπ^- mass. In the mass region 1.1 to 1.9 GeV we measure the fraction of longitudinal polarization of the D^(*+) to be ΓL/Γ=0.654±0.042(stat.)±0.016(syst.). This is in agreement with the expectations from heavy-quark effective theory and factorization assuming that the decay proceeds as B^(-0)→D^(*+)ρ(1450)-, ρ(1450)^-→ωπ^-

    Search for the charmed pentaquark candidate Θ_c(3100)^0 in e^+e^- annihilations at √s=10.58  GeV

    Get PDF
    We search for the charmed pentaquark candidate reported by the H1 collaboration, the Θ_c(3100)^0, in e^+e^- interactions at a center-of-mass (c.m.) energy of 10.58 GeV, using 124  fb^(-1) of data recorded with the BABAR detector at the PEP-II e^+e^- facility at SLAC. We find no evidence for such a state in the same pD^(*-) decay mode reported by H1, and we set limits on its production cross section times branching fraction into pD^(*-) as a function of c.m. momentum. The corresponding limit on its total rate per e^+e^-→qq event, times branching fraction, is about 3 orders of magnitude lower than rates measured for the charmed Λ_c and Σ_c baryons in such events

    Observation of B^0 Meson Decay to a_1^±(1260)π^∓

    Get PDF
    We present a measurement of the branching fraction of the decay B^0→a_1^±(1260)π^∓ with a_1^±(1260)→π^∓π^±π^±. The data sample corresponds to 218×10^6 BB pairs produced in e^+e^- annihilation through the ΄(4S) resonance. We measure the branching fraction B(B^0→a_1^±(1260)π^∓)B(a_1^±(1260)→π^∓π^±π^±)=(16.6±1.9±1.5)×10^(-6), where the first error quoted is statistical and the second is systematic
    • 

    corecore