Using 13.6/fb of continuum two-jet e+e- -> ccbar events collected with the CLEO detector, we have searched for baryon number correlations at the primary quark level. We have measured the likelihood for a /\c+ charmed baryon to be produced in the hemisphere opposite a /\c- relative to the likelihood for a /\c+ charmed baryon to be produced opposite an anticharmed meson Dbar; in all cases, the reconstructed hadrons must have momentum greater than 2.3 GeV/c. We find that, given a /\c- (reconstructed in five different decay modes), a /\c+ is observed in the opposite hemisphere (0.72+/-0.11)% of the time (not corrected for efficiency). By contrast, given a Dbar in one hemisphere, a /\c+ is observed in the opposite hemisphere only (0.21+/-0.02)% of the time. Normalized to the total number of either /\c- or Dbar ``tags'', it is therefore 3.52+/-0.45+/-0.42 times more likely to find a /\c+ opposite a /\c- than a Dbar meson. This enhancement is not observed in the JETSET 7.3 e+e- -> ccbar Monte Carlo simulation.
This paper describes new measurements from CLEO of the inclusive B→Ds+X branching fraction as well as the B+→Ds(*)+D¯(*)0 and B0→Ds(*)+D(*)− branching fractions. The inclusive branching fraction is B(B→Ds+X)=(12.11±0.39±0.88±1.38)% where the first error is statistical, the second is the systematic error, and the third is the error due to the uncertainty in the Ds+→φπ+ branching fraction. The branching fractions for the B→Ds(*)+D¯(*) modes are found to be between 0.9% and 2.4% and are significantly more precise than previous measurements. The sum of the B→Ds(*)+D¯(*) branching fractions is consistent with the results of fits to the inclusive Ds+ momentum spectrum. Factorization is used to arrive at a value for fDs, the Ds+ decay constant. © 1996 The American Physical Society.
A measurement of the spin alignment of charged D^* mesons produced in continuum e^+ e^- \to c \bar{c} events at \sqrt{s}=10.5 GeV is presented. This study using 4.72 fb^{-1} of CLEO II data shows that there is little evidence of any D^* spin alignment.
Using the CLEO II detector at CESR, we have observed two charmed states, where the higher mass state decays to D 0 π + and to D ∗0 π + , while the lower mass state decays to D ∗0 π + , but not to D 0 π + . The masses and widths were measured to be 2425±2±2 MeV/c 2 and 26 −7−4 +8+4 MeV/c 2 for the lower mass state, and 2463±3±3 MeV/c 2 and 27 −8−5 +11+5 MeV/c 2 for the higher mass state. Properties of these states, including their decay angular distributions and spin-parity assignments have been studied. The results of this analysis support the identification of these states as the charged L = 1 D 1 (2420) + and D 2 ∗ (2460) + , respectively. The isospin mass splittings between these states and their neutral partners have also been measured. This is the first full reconstruction of any decay mode of the D 1 (2420) + and the first observation of the decay of D 2 ∗ (2460) + to D ∗0 π + .
Using the CLEO~II detector, we have measured the differential cross sections for exclusive two-photon production of light pseudoscalar mesons $\pi^0$, $\eta$, and $\eta^{\prime}$. From our measurements we have obtained the form factors associated with the electromagnetic transitions $\gamma^*\gamma$ $\to$ meson. We have measured these form factors in the momentum transfer ranges from 1.5 to 9, 20, and 30 GeV$^2$ for $\pi^0$, $\eta$, and $\eta^{\prime}$, respectively, and have made comparisons to various theoretical predictions.
Using data collected by the CLEO II detector, we have observed two states decaying to Λc+π+π−. Relative to the Λc+, their mass splittings are measured to be +307.5±0.4±1.0 and +342.2±0.2±0.5MeV/c2, respectively; this represents the first measurement of the less massive state. These two states are consistent with being orbitally excited, isospin zero Λc+ states.
Using data recorded by the CLEO-II detector at CESR, we report the first observation of a narrow state decaying into $\Xi_c~+\pi~-$. The state has mass difference $M(\Xi_c~+\pi~-)-M(\Xi_c~+)$ of $178.2\pm0.5\pm1.0$ $\rm{MeV/c~2}$, and a width of $<5.5$ $\rm{MeV/c~2}$ (90\% confidence level limit). The most likely explanation of this new state is that it is the $J=\32$ spin excitation of the $\Xi_c~0$ charmed baryon.
Using data collected in the region of the Upsilon(4S) resonance with the CLEO II detector operating at the Cornell Electron Storage Ring CESR, we present the first observation of B mesons decaying into the charmed strange baryons Xi_c0 and Xi_c+. We find 79 +/- 27 Xi_c0 and 125 +/- 28 Xi_c+ candidates from B decays, leading to product branching fractions of BR(Bbar -> Xi_c0 X)BR(Xi_c0 -> Xi- pi+) = (0.144 +/- 0.048 +/- 0.021) x 10~-3 and BR(Bbar -> Xi_c+ X)BR(Xi_c+ -> Xi- pi+ pi+) = (0.453 +/- 0.096 +0.085-0.065) x 10~-3.
Using the CLEO detector at the Cornell Electron Storage Ring, we have made a measurement of R=sigma(e+e- ->hadrons)/sigma(e+e- ->mu+mu-) =3.56+/-0.01+/-0.07 at ECM=10.52 GeV. This implies a value for the strong coupling constant of alpha_s(10.52 GeV)=0.20+/-0.01+/-0.06, or alpha_s(M_Z)=0.13+/-0.005+/-0.03.
Using the CLEO detector at the Cornell $e~+e~-$ storage ring, CESR, we study the two-photon production of $\Lambda \overline{\Lambda}$, making the first observation of $\gamma \gamma \to \Lambda \overline{\Lambda}$. We present the cross-section for $ \gamma \gamma \to \Lambda \overline{\Lambda}$ as a function of the $\gamma \gamma$ center of mass energy and compare it to that predicted by the quark-diquark model.
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