In a sample of B mesons from the decay of the ϒ(4S) produced in e+e− collisions at the Cornell Electron Storage Ring, inclusive protons, antiprotons, lambdas, and antilambdas have been observed. Lower limits to the B-to-baryon branching ratios are derived.
NUMERICAL VALUES OF DATA SUPPLIED BY E.H. THORNDIKE. CORRECTED ANTI(PROTON) PRODUCTION FROM UPSI(4S) DECAY.
NUMERICAL VALUES OF DATA SUPPLIED BY E.H. THORNDIKE. CORRECTED ANTI(LAMBDA) PRODUCTION FROM UPSI(4S) DECAY.
A factorial moment analysis has been performed on the differential multiplicity distributions of hadronic final states of the Z 0 recorded with the OPAL detector at LEP. The moments of the one-dimensional rapidity and the two-dimensional rapidity versus azimuthal angle distributions are found to exhibit “intermittent” behaviour attributable to the jet structure of the events. The moments are reproduced by both parton shower and matrix element QCD based hadronisation models. No evidence for fluctuations beyond those attributable to jet structure is observed.
Corrected factorial moments of the rapidity distribution with respect to the sphericity axis. The errors shown are statistical only but include the statistical error onthe correction factor, added in quadrature.
Corrected factorial moments of the rapidity distribution with respect to the electron beam axis. The errors shown are statistical only but include the statistical error onthe correction factor, added in quadrature.
Corrected factorial moments of the rapidity (with respect to the sphericityaxis) versus PHI distribution. For each point the NUMBER of bins are constructe d from equal numbers of YRAP and PHI bins. The errors shown are statistical only but include the statistical error onthe correction factor, added in quadrature.
We report on an improved measurement of the value of the strong coupling constant σ s at the Z 0 peak, using the asymmetry of the energy-energy correlation function. The analysis, based on second-order perturbation theory and a data sample of about 145000 multihadronic Z 0 decays, yields α s ( M z 0 = 0.118±0.001(stat.)±0.003(exp.syst.) −0.004 +0.0009 (theor. syst.), where the theoretical systematic error accounts for uncertainties due to hadronization, the choice of the renormalization scale and unknown higher-order terms. We adjust the parameters of a second-order matrix element Monte Carlo followed by string hadronization to best describe the energy correlation and other hadronic Z 0 decay data. The α s result obtained from this second-order Monte Carlo is found to be unreliable if values of the renormalization scale smaller than about 0.15 E cm are used in the generator.
Value of LAMBDA(MSBAR) and ALPHA_S.. The first systematic error is experimental, the second is from theory.
The EEC and its asymmetry at the hadron level, unfolded for initial-state radiation and for detector acceptance and resolution. Errors include full statistical and systematic uncertainties.
The production of enutral kaons in e + e − annihilation has been measured for c.m. energies between 3.4 GeV and 7.6 GeV. Near 4 GeV the inclusive K S cross section shows an increase and structure similar to total hadron production. Roughly 40–45% of all hadronic final states contain kaons, except at 4.028 GeV and 4.415 GeV, where a significantly larger kaon fraction is observed.
No description provided.
THIS IS TWICE THE MEASURED KS CROSS SECTION. THE ERRORS ARE STATISTICAL ONLY. THERE IS 15 PCT ABSOLUTE NORMALIZATION ERROR, PLUS POSSIBLY SOME ENERGY DEPENDENT ERROR. THE DATA ARE NOT EQUALLY SPACED IN THE ENERGY INTERVALS.
The inclusive production of antiprotons and Λ's in e+e− annihilation has been measured as a function of the c.m. energy in the range 3.7-7.6 GeV. We find that the baryon cross section has a behavior different from the total hadronic production. Our results show a rapid rise in the ratio σp¯σμμ between 4.4 and 5 GeV, consistent with what would be expected from charmed baryon production. Λ¯ production is 10-15% of p¯ production at all energies.
NOT INCLUDING SYSTEMATIC ERRORS.
Inclusive momentum and energy spectra of neutral and charged D-mesons produced in e + e − annihilation at energies near 7 GeV are presented. The slope of the energy spectrum is similar to the charged pion spectrum at the same energy. The inclusive cross section σ(e + e − → D or D + anything) at 7 GeV is 4.8±1.3 nb.
No description provided.
No description provided.
SCALING VARIABLE IS X(P=3,DEF=2*E(P=3)/SQRT(S)) > 0.54.
Decay modes of the charmed mesons, D 0 and D + , are studied in e + e − annihilation data at 4.03 and 4.41 GeV c.m. energy. The products of cross section times branching ratio are measured for the K − π + , K − π + π + π − , K S π + π − and K − π + π + final states. Upper limits are established for the Cabibbo forbidden decays via π + π − , K + K − , K + K − π + , K + π + π − and π + π − π + . The K − π + π + π − final state is shown to be dominated by K − π + ρ 0 .
THESE PARTIAL CROSS SECTIONS ARE CONVERTED TO TOTAL D INCLUSIVE CROSS SECTIONS USING KNOWN BRANCHING RATIOS AND TABULATED IN M. PICCOLO ET AL., PL 86B, 220 (1979).
A peak in the pK−π+ and p¯K+π− invariant-mass spectra at 2.285±0.006 GeV/c2 is observed, which is associated with the lowest-lying charmed baryon (Λc). A cross section times branching ratio of 0.037±0.012 nb at Ec.m.=5.2 GeV is measured with a substantial fraction of the events produced with an equal recoiling mass. New measurements of inclusive p and Λ cross sections are also presented, allowing an estimate of the branching ratio B(Λc→pK−π+)=0.022±0.010.
THE TOTAL INCLUSIVE CHARMED LAMBDA CROSS SECTION IS DERIVED FROM THE OBSERVED PRODUCTION RATE VIA THE <P K- PI+> CHANNEL USING THE STEP IN INCLUSIVE PROTON PRODUCTION AT THE CHARMED-BARYON THRESHOLD AND REASONABLE ASSUMPTIONS. THE BRANCHING RATIO (LAMBDA/C+ --> P K- PI+) IS THEN 2.2 +- 1.0 PCT.
ACTUALLY TWICE THE INCLUSIVE ANTI-PROTON CROSS SECTION (EACH BARYON PAIR IS COUNTED TWICE).
EACH BARYON PAIR PRODUCED IS OF COURSE COUNTED TWICE IN THIS CROSS SECTION.
Three narrow resonances have been observed in e+e− annihilation into hadrons at total energies between 9.4 and 10.4 GeV. Measurements of mass spacing and ratios of lepton pair widths support the interpretation of these "ϒ" states as the lowest triplet-S levels of the bb¯ quark-antiquark system.
No description provided.
A fourth state in the upsilon energy region has been seen in e+e− collisions at the Cornell Electron Storage Ring. A resonance is observed with a mass 1112±5 MeV above the lowest upsilon state. The 9.6-MeV rms width is greater than the 4.6-MeV energy resolution of the e+e− beams. The observed characteristics of the new state make it a likely candidate for the 4S3 state of the bb¯ system, lying above the threshold for the production of B mesons.
NOT CORRECTED FOR TAU HEAVY LEPTON PRODUCTION NOR TWO-PHOTON COLLISIONS.
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