501 research outputs found

### Determination of the B -> D^*+l-nu Decay Width and |V_{cb}|

We determine the CKM matrix element |Vcb| using a sample of 3.33 million
BBbar events in the CLEO detector at CESR. We determine the yield of
reconstructed B --> D*+ l nu decays as a function of w = v_B . v_D*, and from
this we obtain the differential decay rate d\Gamma/dw. By extrapolating the
differential decay rate to w=1, the kinematic point at which the D* is at rest
relative to the B, we extract the product |Vcb| F(1), where F(1) is the form
factor at w=1 and is predicted accurately by theory. We find |Vcb| F(1) =
0.0424 +- 0.0018(stat.) +- 0.0019(syst.). We also integrate the differential
decay rate over w to obtain B(B --> D*+ l nu) = (5.66 +- 0.29 +- 0.33)%. All
results are preliminary.Comment: Contribution to XXXth International Conference on High Energy
Physics, July 2000, Osaka, Japa

### Observation of the Omega_c Charmed Baryon at CLEO

The CLEO detector at the CESR collider has used 13.7 fb^{-1} to search for
the production of Omega_c (css-ground state) in e^{+}e^{-} collisions at
sqrt{s} = 10.6 GeV The modes used to study the Omega_c are Omega- pi+, Omega-
pi+ pi0, Xi- K- pi+ pi+, Xi0 K- pi+, and Omega- pi+ pi+ pi-. We observe 40.4 +-
9.0(stat) combined events at a mass of 2694.6 +- 2.6(stat) +- 2.4(syst) MeV. We
have also measured the \sigma * Br of the above modes for xp > 0.5 to be 11.3
+- 3.9 +- 2.3 fb, 47.6 +- 18.0 +- 2.8 fb, 45.1 +- 23.2 +- 4.1 fb, 18.2 +- 10.6
+- 3.8 fb, and <5.1 fb @ 90 % CL, respectively.Comment: Submitted to XXXth International Conference on High Energy Physics,
July 2000, Osaka, Japa

### Recent Results From CLEO on D0-D0Bar Mixing, CP Violation in D0 Decays, and D*+ Width

We present preliminary results of several analyses searching for the effects
of CP violation and mixing in the decay of $D^0$ mesons. We find no evidence of
CP asymmetry in five different two-body decay modes of the $D^0$ to pairs of
light pseudo-scalar mesons: $A_{CP}(K^+ K^-) = (+0.05 \pm 2.18 \pm 0.84)%$,
$A_{CP}(\pi^+ \pi^-) = (+2.0 \pm 3.2 \pm 0.8)%$, $A_{CP}(K^0_{\rm S} \pi^0) =
(+0.1 \pm 1.3)%$, $A_{CP}(\pi^0 \pi^0) = (+0.1 \pm 4.8)%$, and $A_{CP}(K^0_{\rm
S} K^0_{\rm S}) = (-23 \pm 19)%$. We present the first measurement of the rate
of wrong-sign $D^0 \to K^+ \pi^- \pi^0$ decay: $R = 0.0043^{+0.0011}_{-0.0010}
\pm 0.0007$. We also describe a measurement of the mixing parameter $y_{CP}=
{\Delta\Gamma\over 2 \Gamma}$ by searching for a lifetime difference between
the CP neutral $K^{-}\pi^{+}$ final state and the CP even $K^+K^-$ and
$\pi^+\pi^-$ final states. Under the assumption that CP is conserved we find
$y_{CP} = -0.011 \pm 0.025 \pm 0.014$. Finally, we present our measurement of
the \dstarp width: $96 \pm 4 \pm 22$~k$e$V.Comment: 6 pages, Proceedings of the Fourth International Conference on B
Physics & CP Violatio

### Observation of New States Decaying into Lambda_c^+pi-pi+

Using 13.7 fb^{-1} of data recorded by the CLEO detector at CESR, we
investigate the spectrum of charmed baryons which decay into Lambda_c^+ pi^-
pi^+ and are more massive than the Lambda_{c1} baryons. We find evidence for
two new states: one is broad and has an invariant mass roughly 480 MeV above
that of the Lambda_c^+; the other is narrow with an invariant mass of 596 +- 1
+- 2 MeV above the Lambda_c^+ mass. These results are preliminary.Comment: Contributed to XXXth International Conference on High Energy Physics,
July 2000, Osaka, Japa

### Study of Two-Body B Decays to Kaons and Pions: Observation of B->pi+pi-, B-> K+-pi0, and B-> K0pi0 Decays

We have studied charmless hadronic decays of B mesons into two-body final
states with kaons and pions and observe three new processes with the following
branching fractions: BR(B-> pi+ pi-) = (4.3^{+1.6}_{-1.4} \pm 0.5) \times
10^{-6}, BR(B-> K0 pi0) = (14.6^{+5.9+2.4}_{-5.1-3.3}) \times 10^{-6}, and
BR(B-> K+- pi0) = (11.6^{+3.0+1.4}_{-2.7-1.3}) \times 10^{-6}. We also update
our previous measurements for the decays B->K+- pi-+ and B-> K0 pi+-.Comment: 10 pages, 3 figure

### Study of charmless hadronic B decays into the final states $K\pi, \pi\pi$, and KK, with the first observation of $B \to \pi^+ \pi^-$ and $B\to K^0\pi^0$

We have studied charmless hadronic decays of B mesons into two-body final
states with kaons and pions. We present preliminary results based on 9.66
million $B\bar{B}$ pairs collected with the CLEO detector. We have made the
first observation of the decay $B \to \pi^+\pi^-$, with the branching fraction
of $Br(B \to \pi^+ \pi^-) = (4.7^{+1.8}_{-1.5} \pm 0.6) \times 10^{-6}$. We
have also observed for the first time the decay $B \to K^0\pi^0$ with the
branching fraction of $Br(B \to K^0 \pi^0) = (14.8^{+5.9+2.4}_{-5.1-3.3})
\times 10^{-6}$, thus completing the set of four $K\pi$ branching fraction
measurements. We present improved measurements for the decays $B\to
K^{\pm}\pi^{\mp}$, $B^{\pm}\to K^0\pi^{\pm}$, and $B^{\pm}\to K^{\pm}\pi^0$. We
use these and other charmless hadronic B decays to make a first determination
of the value of the weak phase ${\rm Arg}(V^*_{ub})=\gamma =
{113^\circ}^{+25^\circ}_{-23^\circ}$.Comment: Leppho99 conference submission. All results are preliminar

### Comparison of D to K0L pi and D to K0S pi Decay Rates

We present preliminary measurements of D to K^0_L pi and D to K^0_S pi
branching fractions using 281 pb^{-1} of psi(3770) data at the CLEO-c
experiment. We find that BF(D^0 to KS pi^0) is larger than BF(D^0 to KL pi^0),
with an asymmetry of R(D^0) = 0.122 +- 0.024 +- 0.030. For BF(D^+ to KS pi^+)
and BF(D^+ to KL pi^+), we observe no measureable difference; the asymmetry is
R(D^+) = 0.030 +- 0.023 +- 0.025. Under reasonable theoretical assumptions,
these measurements imply a value for the D^0 to K^+- pi^-+ strong phase that is
consistent with zero. The results presented in this document are preliminary.Comment: 17 pages postscript,also available through
http://www.lepp.cornell.edu/public/CONF/2006, Conrtibuted to ICHEP0

### Charged Track Multiplicity in B Meson Decay

We have used the CLEO II detector to study the multiplicity of charged
particles in the decays of B mesons produced at the $\Upsilon(4S)$ resonance.
Using a sample of 1.5 x 10^6 B meson pairs, we find the mean inclusive charged
particle multiplicity to be 10.71 +- 0.02 +0.21/-0.15 for the decay of the
pair. This corresponds to a mean multiplicity of 5.36 +- 0.01 +0.11/-0.08 for a
single B meson. Using the same data sample, we have also extracted the mean
multiplicities in semileptonic and nonleptonic decays. We measure a mean of
7.82 +- 0.05 +0.21/-0.19 charged particles per $B\bar{B}$ decay when both
mesons decay semileptonically. When neither B meson decays semileptonically, we
measure a mean charged particle multiplicity of 11.62 +- 0.04 +0.24/-0.18 per
$B\bar{B}$ pair.Comment: 11 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN

### Measurement of B9Upsilon(5S) to Bs(*) Bs(*)bar Using phi Mesons

Knowledge of the Bs decay fraction of the Y(5S) resonance, fs, is important
for Bs meson studies at the Y(5S) energy. Using data collected by the CLEO III
detector at CESR consisting of 0.423 1/fb on the Y(5S) resonance, 6.34 1/fb on
the Y(4S) and 2.32 1/fb in the continuum below the Y(4S), we measure B(Y(5S)->
phi X)=(13.2+/- 0.7 ^{+2.2}_{-1.4})% and B(Y (4S)-> phi X)=(7.1 +/- 0.1 +/-
0.6)%, the ratio of the two rates is (1.9 +/- 0.1 ^{+0.3}_{-0.2}). This is the
first measurement of the phi meson yield from the Y(5S). Using these rates, and
a model dependent estimate of B(Bs -> phi X), we measure fs=(27.3 +/- 3.2
^{+14.6}_{-~6.1})%. We update our previous, independent measurement of this
branching fraction using the inclusive Ds yields to be (21.8 +/- 3.4
^{+8.5}_{-4.2})%, due to changes in the $D_s^+ -> phi \pi^+$ branching fraction
and a better estimate of the number of hadronic events. We also report the
total Y(5S) hadronic cross section above continuum to be sigma(e^+e^- ->
Y(5S))=(0.301 +/- 0.002 +/- 0.039) nb. This allows us to extract the fraction
of B mesons as (58.9+/-10.0+/-9.2)%, equal to 1-fs. Averaging the three methods
gives a model dependent result of fs=(26^{+7}_{-4})%.Comment: 23 pages postscript,also available through
http://www.lns.cornell.edu/public/CONF/2006/, Contributed to ICHEP0

### Radiative Decays of the Upsilon(1S) to gamma pi^0 pi^0, and gamma eta eta and gamma pi^0 eta

We report on a study of exclusive radiative decays of the Upsilon(1S)
resonance into the final states gamma pi^0 pi^0, gamma eta eta and gamma pi^0
eta, using 1.13 inverse femto-barn of e^+ e^- annihilation data collected at
sqrt(s)= 9.46 GeV with the CLEO III detector operating at the Cornell Electron
Storage Ring. In the channel gamma pi^0 pi^0, we measure the branching ratio
for the decay mode Upsilon(1S) to gamma f_2(1270) to be (10.5 \pm 1.6 (+
1.9)(-1.8)) x 10^-5. We place upper limits on the product branching ratios for
the isoscalar resonances f_0(1500) and f_0(1710) for the pi^0 pi^0 and eta-eta
decay channels. We also set an upper limit on the Upsilon(1S) radiative decay
into pi^0 eta.Comment: 8 pages postscript,also available through
http://www.lns.cornell.edu/public/CLNS/2005/, Submitted to PR

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