We report results from two new methods for measuring the total production of charmed particles in nonresonant e+e− annihilations at √s =10.5 GeV. The rate for detection of events containing two reconstructed charmed mesons relative to that for events containing one is used to extract information about total charm production independent of decay branching fractions. The value of ΔRcc¯, the total charm-pair cross section normalized to the pointlike μ-pair cross section, is found to be 1.13−0.13+0.17±0.09, under an assumption of limited particle correlations. In an independent analysis the inclusive cross section for e+e−→qq¯→e±X is measured to be 0.293±0.017±0.017 nb. Using measured relative production rates and semileptonic branching fractions of D0 and D+ mesons and estimates of these quantities for Ds and Λc, this is found to correspond to ΔRcc¯=2.07±0.12±0.26. These two measurements are discussed in the context of measurements made by reconstruction of exclusive hadronic decay modes and of theoretical expectations.
Charm quarks production cross section (C=CQCQBQR) evaluated from tagged events.
Results using method 1).
Results using method 2).
We have observed Σc++ and Σc0 baryons in nonresonant e+e− interactions through their decays to Λc+π± using the CLEO detector. The mass difference M(Σc++)-M(Λc+) is measured to be 167.8±0.4±0.3 MeV; for M(Σc0)-M(Λc+) we find 167.9±0.5±0.3 MeV. Σc decay accounts for (18±3±5)% of Λc+ production.
The cross section ratio is multiplied by a factor of 1.5 to account for theunobserved SIGMA/C(2455)+.
No description provided.
Using the CLEO detector at the Cornell Electron Storage Ring, we observe B-meson decays to Λc+ and report on improved measurements of inclusive branching fractions and momentum spectra of other baryons. For the inclusive decay B¯→Λc+X with Λc+→pK−π+, we find that the product branching fraction B(B¯→Λc+X)B(Λc+→pK−π+)=(0.273±0.051±0.039)%. Our measured inclusive branching fractions to noncharmed baryons are B(B→pX)=(8.0±0.5±0.3)%, B(B→ΛX)=(3.8±0.4±0.6)%, and B(B→Ξ−X)=(0.27±0.05±0.04)%. From these rates and studies of baryon-lepton and baryon-antibaryon correlations in B decays, we have estimated the branching fraction B(B¯→Λc+X) to be (6.4±0.8±0.8)%. Combining these results, we calculate B(Λc+→pK−π+) to be (4.3±1.0±0.8)%.
No description provided.
No description provided.
No description provided.
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.
CONST(NAME=EPS) is the parameter of the Peterson fragmentation function (C.Peterson et al., PR D27, 105 (1983)) D(N)/D(Z) = FD(Z) = const * (1/Z)*1/(1 - (1/Z)-CONST(NAME=EPS)/(1-Z))**2. Charged conjugated states are understood.
Charged conjugated states are understood.
Charged conjugated states are understood.
Using the CLEO-II detector at CESR, we have observed the D s 1 (2536) + in the decay modes D s1 + →D ∗0 K + and D ∗+ K S + , and measured its fragmentation and production ratios. Using the helicity angle distribution of the daugter D ∗0 , we obtain new evidence for the assignment of 1 + for the spin and parity of the D s 1 + . We also set upper limits on the decays D s1 + →D s ∗+ λ, D 0 K + and D + K s 0 .
No description provided.
No description provided.
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 + .
CONST(NAME=EPS) is the parameter of the Peterson fragmentation function (C.Peterson et al., PR D27, 105 (1983)) D(N)/D(Z) = FD(Z) = const * (1/Z)*1/(1 - (1/Z)-CONST(NAME=EPS)/(1-Z))**2. Charged conjugate states are undestood.
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.
FORMFACTOR(NAME=FP,C=DECAY CONSTANT) is pseudoscalar meson decay constant. Three different methods are used: 1) C=MUNU: D/S+ --> MU+ NUMU, 2) C = ENU: B --> D/S+ D*BAR / B --> D*BAR E+ NU, and 3) C = PI : B --> D/S+ D*BAR / B0 - -> PI+(RHO+) D*BAR-. The F(D/S) is evaluated from B decay assuming the factorization.
The CLEO II detector is used to search for the production of χc2 states in two-photon interactions. We use the signature χc2→γJ/ψ→γl+l− with l=e,μ. Using 1.49 fb−1 of data taken with beam energies near 5.29 GeV, the two-photon width of the χc2 is determined to be Γ(χc2→γγ)=1.08±0.30(stat)±0.26(syst) keV, in agreement with predictions from perturbative QCD.
Results below were obtained usign J/psi from-factors in the two photon propogators, and assumes that only transversely polarized photons are significant inthe production of the CHI/C2(1P) state.
No description provided.
We have observed five new decay modes of the charmed baryon Λc+ using data collected with the CLEO II detector. Four decay modes, Λc+→pK¯0η, Ληπ+, Σ+η, and Σ*+η, are first observations of final states with an η meson, while the fifth mode, Λc+→ΛK¯0K+, requires the creation of an ss¯ quark pair. We measure the branching fractions of these modes relative to Λc+→pK−π+ to be 0.25±0.04±0.04, 0.35±0.05±0.06, 0.11±0.03±0.02, 0.17±0.04±0.03, and 0.12±0.02±0.02, respectively.
Integrated luminosity of 3.25 fb-1 have used, which corresponds to about 4 million C CBAR events.. Here X=P(LAMBDA/C)/sqrt(Ebeam**2-M(LAMBDA/C)**2).
Integrated luminosity of 3.25 fb-1 have used, which corresponds to about 4 million C CBAR events.. Here X=P(LAMBDA/C)/sqrt(Ebeam**2-M(LAMBDA/C)**2).
Integrated luminosity of 3.25 fb-1 have used, which corresponds to about 4 million C CBAR events.. Here X=P(LAMBDA/C)/sqrt(Ebeam**2-M(LAMBDA/C)**2).
A measurement of the cross section for the combined two-photon production of charged pion and kaon pairs is performed using 1.2~$\rm fb^{-1}$ of data collected by the CLEO~II detector at the Cornell Electron Storage Ring. The cross section is measured at invariant masses of the two-photon system between 1.5 and 5.0 GeV/$c^2$, and at scattering angles more than $53^\circ$ away from the $\gamma\gamma$ collision axis in the $\gamma\gamma$ center-of-mass frame. The large background of leptonic events is suppressed by utilizing the CsI calorimeter in conjunction with the muon chamber system. The reported cross section is compared with leading order QCD models as well as previous experiments. In particular, although the functional dependence of the measured cross section disagrees with leading order QCD at small values of the two-photon invariant mass, the data show a transition to perturbative behavior at an invariant mass of approximately 2.5 GeV/$c^2$. hardcopies with figures can be obtained by writing to to: Pam Morehouse preprint secretary Newman Lab Cornell University Ithaca, NY 14853 or by sending mail to: preprints@lns62.lns.cornell.edu
There is an additional 10 pct point-to-point systematic error as well as the overall uncertainty given above.
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