2,510 research outputs found
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
Optimal Strategies for Sinusoidal Signal Detection
We derive and study optimal and nearly-optimal strategies for the detection
of sinusoidal signals hidden in additive (Gaussian and non-Gaussian) noise.
Such strategies are an essential part of algorithms for the detection of the
gravitational Continuous Wave
(CW) signals produced by pulsars. Optimal strategies are derived for the case
where the signal phase is not known and the product of the signal frequency and
the observation time is non-integral.Comment: 18 pages, REVTEX4, 7 figures, 2 table
Thermoelastic Noise and Homogeneous Thermal Noise in Finite Sized Gravitational-Wave Test Masses
An analysis is given of thermoelastic noise (thermal noise due to
thermoelastic dissipation) in finite sized test masses of laser interferometer
gravitational-wave detectors. Finite-size effects increase the thermoelastic
noise by a modest amount; for example, for the sapphire test masses tentatively
planned for LIGO-II and plausible beam-spot radii, the increase is less than or
of order 10 per cent. As a side issue, errors are pointed out in the currently
used formulas for conventional, homogeneous thermal noise (noise associated
with dissipation which is homogeneous and described by an imaginary part of the
Young's modulus) in finite sized test masses. Correction of these errors
increases the homogeneous thermal noise by less than or of order 5 per cent for
LIGO-II-type configurations.Comment: 10 pages and 3 figures; RevTeX; submitted to Physical Review
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
Search for the decay B→D_(s1)^+ (2536)X
We have searched for the decay B⃗D_(s1)^+(2536)X and measured an upper limit for the inclusive branching fraction of B(B⃗D_(s1)^+X)<0.96% at the 90% confidence level. This limit is small compared with the total expected B⃗D^((*))D^((*))KX rate. Assuming factorization, the D_(s1)^+ decay constant is constrained to be fD_(s1)^+<114 MeV at the 90% confidence level, at least 2.5 times smaller than that of D_s^+
Limits on Flavor Changing Neutral Currents in D^0 Meson Decays
Using the CLEO II detector at the Cornell Electron Storage Ring, we have searched for flavor changing neutral currents and lepton family number violations in D^0 meson decays. The upper limits on the branching fractions for D^0→ℓ^+ℓ^- and D^0→X^0ℓ^+ℓ^- are in the range 10^(-5) to 10^(-4), where X^0 can be a π^0, K_s^0, η, ρ^0, ω, K̅^(*0), or φ meson, and the ℓ^+ℓ^- pair can be e^+e^-, μ^+μ^-, or e^±μ^∓. Although these limits are above the theoretical predictions, most are new or an order of magnitude lower than previous limits
Measurement of the total cross section for e^+e^-→hadrons at √s=10.52 GeV
Using the CLEO detector at the Cornell Electron Storage Ring, we have made a measurement of R≡σ(e^+e^-→hadrons)/σ(e^+e^-→μ^+μ^-)=3.56±0.01±0.07 at √s=10.52 GeV. This implies a value for the strong coupling constant of α_s(10.52 GeV)=0.20±0.01±0.06, or α_s(MZ)=0.13±0.005±0.03
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.)
Search for color-suppressed B hadronic decay processes at the Υ(4S) resonance
Using 3.1fb^(-1) of data accumulated at the Υ(4S) by the CLEO-II detector, corresponding to 3.3×10^6 BB̅ pairs, we have searched for the color-suppressed B hadronic decay processes B^(0) → D^(0)(D^(*0))X^0, where X^0 is a light neutral meson π^0, ρ^0, η, η′ or ω. The D^(*0) mesons are reconstructed in D^(*0) → D^(0)π^(0) and the D^0 mesons in D^(0) → K^(-)π^(+), K^(-)π^(+)π^(0) and K^(-)π^(+)π^(+)π^(-) decay modes. No obvious signal is observed. We set 90% C.L. upper limits on these modes, varying from 1.2×10^(-4) for B^(0) → D^(0)π^(0) to 1.9×10^(-3) for B^(0) → D^(*0)η′
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