685 research outputs found
Branching Fractions of tau Leptons to Three Charged Hadrons
From electron-positron collision data collected with the CLEO detector
operating at CESR near \sqrt{s}=10.6 GeV, improved measurements of the
branching fractions for tau decays into three explicitly identified hadrons and
a neutrino are presented as {\cal
B}(\tau^-\to\pi^-\pi^+\pi^-\nu_\tau)=(9.13\pm0.05\pm0.46)%, {\cal B}(\tau^-\to
K^-\pi^+\pi^-\nu_\tau)=(3.84\pm0.14\pm0.38)\times10^{-3}, {\cal B}(\tau^-\to
K^-K^+\pi^-\nu_\tau)=(1.55\pm0.06\pm0.09)\times10^{-3}, and {\cal B}(\tau^-\to
K^-K^+K^-\nu_\tau)<3.7\times10^{-5} at 90% C.L., where the uncertainties are
statistical and systematic, respectively.Comment: 10 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, to appear in Phys. Rev. Let
Improved Measurement of the Form Factors in the Decay Lambda_c^+ --> Lambda e^+ nu_e
Using the CLEO detector at the Cornell Electron Storage Ring, we have studied
the distribution of kinematic variables in the decay Lambda_c^+ -> Lambda e^+
nu_e. By performing a four-dimensional maximum likelihood fit, we determine the
form factor ratio, R = f_2/f_1 = -0.31 +/- 0.05(stat) +/- 0.04(syst), the pole
mass, M_{pole} = (2.21 +/- 0.08(stat) +/- 0.14(syst)) GeV/c^2, and the decay
asymmetry parameter of the Lambda_c, alpha_{Lambda_c} = -0.86 +/- 0.03(stat)
+/- 0.02(syst), for = 0.67 (GeV/c^2)^2. We compare the angular
distributions of the Lambda_c^+ and Lambda_c^- and find no evidence for
CP-violation: A_{Lambda_c} = (alpha_{Lambda_c^+} + alpha_{Lambda_c^-})/
(alpha_{Lambda_c^+} - alpha_{Lambda_c^-}) = 0.00 +/- 0.03(stat) +/- 0.01(syst)
+/- 0.02, where the third error is from the uncertainty in the world average of
the CP-violating parameter, A_{Lambda}, for Lambda -> p pi^-.Comment: 8 pages postscript,also available through
http://www.lns.cornell.edu/public/CLNS/2004/, submitted to PR
Inclusive eta' Production from the Upsilon(1S)
Using the CLEO II detector at CESR, we measure the eta' - gluon - gluon
form-factor in Y(1S) decays. This form-factor especially at large eta' energies
may provide an explanation of the large rate for B -> Xs eta'. Our data do not
support a large anomalous coupling at higher q^2 and thus the large eta' rate
remains a mystery, possibly requiring a non-Standard Model explanation.Comment: 14 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, submitted to PR
Measurement of the Inclusive Semi-electronic Branching Fraction
Using the angular correlation between the emitted in a decay and the emitted in the subsequent decay, we have measured the branching fraction for the
inclusive semi-electronic decay of the meson to be: {\cal B}(D^0
\rightarrow X e^+ \nu) = [6.64 \pm 0.18 (stat.) \pm 0.29 (syst.)] \%. The
result is based on 1.7 fb of collisions recorded by the CLEO II
detector located at the Cornell Electron Storage Ring (CESR). Combining the
analysis presented in this paper with previous CLEO results we find,
\frac{{\cal B} (D^0 \rightarrow X e^+ \nu)}
{{\cal B} (D^0 \rightarrow K^- \pi^+)}
= 1.684 \pm 0.056 (stat.) \pm 0.093(syst.) and
\frac{{\cal B}(D\rightarrow K^-e^+\nu)}
{{\cal B}(D\rightarrow Xe^+\nu)}
= 0.581 \pm 0.023 (stat.) \pm 0.028(syst.).
The difference between the inclusive rate and the sum of the measured
exclusive branching fractions (measured at CLEO and other experiments) is of the inclusive rate.Comment: Latex file, 33pages, 4 figures Submitted to PR
Measurements of the Ratios and
Using the CLEO~II detector we measure , and .
We find the vector to pseudoscalar ratio, , which is similar to the
ratio found in non strange decays.Comment: 11 page uuencoded postscript file, postscript file also available
through http://w4.lns.cornell.edu/public/CLN
Tau Neutrino Helicity from Energy Correlations
We report a measurement of the magnitude of the tau neutrino helicity from
tau-pair events taken with the CLEO detector at the CESR electron-positron
storage ring. Events in which each tau undergoes the decay tau -> h nu, with h
a charged pion or kaon, are analyzed for energy correlations between the
daughter hadrons, yielding |xi| = 2*|h_nu| = 1.03 +/- 0.06 +/- 0.04, with the
first error statistical and the second systematic.Comment: 11 pages, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
Study of the q^2-Dependence of B --> pi ell nu and B --> rho(omega)ell nu Decay and Extraction of |V_ub|
We report on determinations of |Vub| resulting from studies of the branching
fraction and q^2 distributions in exclusive semileptonic B decays that proceed
via the b->u transition. Our data set consists of the 9.7x10^6 BBbar meson
pairs collected at the Y(4S) resonance with the CLEO II detector. We measure
B(B0 -> pi- l+ nu) = (1.33 +- 0.18 +- 0.11 +- 0.01 +- 0.07)x10^{-4} and B(B0 ->
rho- l+ nu) = (2.17 +- 0.34 +0.47/-0.54 +- 0.41 +- 0.01)x10^{-4}, where the
errors are statistical, experimental systematic, systematic due to residual
form-factor uncertainties in the signal, and systematic due to residual
form-factor uncertainties in the cross-feed modes, respectively. We also find
B(B+ -> eta l+ nu) = (0.84 +- 0.31 +- 0.16 +- 0.09)x10^{-4}, consistent with
what is expected from the B -> pi l nu mode and quark model symmetries. We
extract |Vub| using Light-Cone Sum Rules (LCSR) for 0<= q^2<16 GeV^2 and
Lattice QCD (LQCD) for 16 GeV^2 <= q^2 < q^2_max. Combining both intervals
yields |Vub| = (3.24 +- 0.22 +- 0.13 +0.55/-0.39 +- 0.09)x10^{-3}$ for pi l nu,
and |Vub| = (3.00 +- 0.21 +0.29/-0.35 +0.49/-0.38 +-0.28)x10^{-3} for rho l nu,
where the errors are statistical, experimental systematic, theoretical, and
signal form-factor shape, respectively. Our combined value from both decay
modes is |Vub| = (3.17 +- 0.17 +0.16/-0.17 +0.53/-0.39 +-0.03)x10^{-3}.Comment: 45 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, submitted to PR
Measurement of Inclusive B --> psi Production
Using the combined CLEO II and CLEO II.V data sets of 9.1 fb^{-1} at the
Upsilon(4S), we measure properties of Psi mesons produced directly from decays
of the B meson, where ``B'' denotes an admixture of B+, B-, B0, and B0bar, and
``Psi'' denotes either J/Psi or Psi(2S). We report first measurements of Psi
polarization in B -> Psi(direct) X: alpha(J/Psi) = -0.30 {+0.07 -0.06 stat}
{+-0.04 syst} and alpha(Psi(2S)) = -0.45 {+0.22 -0.19 stat} {+-0.04 syst}. We
also report improved measurements of the momentum distributions of Psi produced
directly from B decays, correcting for measurement smearing. Finally, we report
measurements of the inclusive branching fraction for B -> Psi X and B -> Chi_c1
X.Comment: 8 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, submitted to PR
Ascorbic Acid, Alcohol, and Environmental Chemicals a
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73093/1/j.1749-6632.1987.tb23775.x.pd
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