46,133 research outputs found
Scalar Wave Falloff in Asymptotically Anti-de Sitter Backgrounds
Conformally invariant scalar waves in black hole spacetimes which are
asymptotically anti-de Sitter are investigated. We consider both the
-dimensional black hole and -dimensional Schwarzschild-anti-de
Sitter spacetime as backgrounds. Analytical and numerical methods show that the
waves decay exponentially in the 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
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 which is appropriate to describe the
shape of wave-packet, and calculate the effective action as a function of both
the dispersion and . 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
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
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
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
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^-
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
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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