46,133 research outputs found

    Scalar Wave Falloff in Asymptotically Anti-de Sitter Backgrounds

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    Conformally invariant scalar waves in black hole spacetimes which are asymptotically anti-de Sitter are investigated. We consider both the (2+1)(2+1)-dimensional black hole and (3+1)(3+1)-dimensional Schwarzschild-anti-de Sitter spacetime as backgrounds. Analytical and numerical methods show that the waves decay exponentially in the (2+1)(2+1) dimensional black hole background. However the falloff pattern of the conformal scalar waves in the Schwarzschild-anti-de Sitter background is generally neither exponential nor an inverse power rate, although the approximate falloff of the maximal peak is weakly exponential. We discuss the implications of these results for mass inflation.Comment: 34 pages, Latex, 26 figures, uses psfi

    Non-perturbative approach for the time-dependent symmetry breaking

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    We present a variational method which uses a quartic exponential function as a trial wave-function to describe time-dependent quantum mechanical systems. We introduce a new physical variable yy which is appropriate to describe the shape of wave-packet, and calculate the effective action as a function of both the dispersion \sqrt{} and yy. The effective potential successfully describes the transition of the system from the false vacuum to the true vacuum. The present method well describes the long time evolution of the wave-function of the system after the symmetry breaking, which is shown in comparison with the direct numerical computations of wave-function.Comment: 8 pages, 3 figure

    Measurement of the B Semileptonic Branching Fraction with Lepton Tags

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    We have used the CLEO II detector and 2.06fb^(-1) of ϒ(4S) data to measure the B-meson semileptonic branching fraction. The B→Xeν momentum spectrum was obtained over nearly the full momentum range by using charge and kinematic correlations in events with a high-momentum lepton tag and an additional electron. We find B(B→Xeν) = (10.49±0.17±0.43)%, with overall systematic uncertainties less than those of untagged single-lepton measurements. We use this result to calculate the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element V_(cb) and to set an upper limit on the fraction of ϒ(4S) decays to final states other than BB̅

    Observation of the Cabibbo-suppressed charmed baryon decay Λ_c^+→pφ

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    We report the observation of the Cabibbo-suppressed decays Λ_c^+→pK^-K^+ and Λ_c^+→pφ using data collected with the CLEO II detector at CESR. The latter mode, observed for the first time with significant statistics, is of interest as a test of color suppression in charm decays. We have determined the branching ratios for these modes relative to Λ_c^+→pK^-π^+ and compared our results with theory

    Higgs Boson Production from Black Holes at the LHC

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    If the fundamental Planck scale is near a TeV, then TeV scale black holes should be produced in proton-proton collisions at the LHC where \sqrt{s} = 14 TeV. As the temperature of the black holes can be ~ 1 TeV we also expect production of Higgs bosons from them via Hawking radiation. This is a different production mode for the Higgs boson, which would normally be produced via direct pQCD parton fusion processes. In this paper we compare total cross sections and transverse momentum distributions d\sigma/dp_T for Higgs production from black holes at the LHC with those from direct parton fusion processes at next-to-next-to-leading order and next-to-leading order respectively. We find that the Higgs production from black holes can be larger or smaller than the direct pQCD production depending upon the Planck mass and black hole mass. We also find that d\sigma/dp_T of Higgs production from black holes increases as a function of p_T which is in sharp contrast with the pQCD predictions where d\sigma/dp_T decreases so we suggest that the measurement of an increase in d\sigma/dp_T as p_T increases for Higgs (or any other heavy particle) production can be a useful signature for black holes at the LHC.Comment: 20 pages latex, 5 figures, To appear in Phys. Rev.

    Measurement of B(D^0 → K^-π^+) Using Partial Reconstruction of B̅ → D^(*+)Xℓ^-ν̅

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    We present a measurement of the absolute branching fraction for D^0→K^-π^+ using the reconstruction of the decay chain B̅ →D^(*+)Xℓ^-ν̅ , D^(*+)→D^0π^+ where only the lepton and the low-momentum pion from the D^(*+) are detected. With data collected by the CLEO II detector at the Cornell Electron Storage Ring, we have determined B(D^0→K^-π^+) = [3.81±0.15(stat)±0.16(syst)]%

    Search for Inclusive b → sl^+l^-

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    We have searched for the effective flavor changing neutral-current decays b→sl^+l^- using an inclusive method. We set upper limits on the branching ratios B(b→se^+e^-)<5.7×10^(-5), B(b→sμ^+μ^-)<5.8×10^(-5), and B(b→se^±μ^∓)<2.2×10^(-5) [at 90% confidence level (C.L.)]. Combing the dielectron and dimuon decay modes we find B(b→sl^+l^-)<4.2×10^(-5) (at 90% C.L.)

    Observation of the Radiative Decay D^(*+) → D^+y

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    We have observed a signal for the decay D^(*+)→D^+γ at a significance of 4 standard deviations. From the measured branching ratio B(D^(*+)→D^+γ)/B(D^(*+)→D^+π^0) = 0.055±0.014±0.010 we find B(D^(*+)→D^+γ) = 0.017±0.004±0.003, where the first uncertainty is statistical and the second is systematic. We also report the highest precision determination of the remaining D^(*+) branching fractions
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