This paper summarizes the measurements one+e− annihilation performed by the DASP Collaboration in the energy range between 3.1 and 5.2 GeV. The following topics are covered: total cross section, production and two body decays of the narrow resonances, radiative decays of theJ/ψ and ψ′ resonances and evidence for theX(2.82), ψ′ cascade decays, inclusive η production and evidence for theF meson, semileptonic decays of charmed mesons and properties of the heavy lepton.
THESE DATA ON R WERE PUBLISHED IN R. BRANDELIK ET AL., PL 76B, 361 (1978), THE RECORD OF WHICH HAS TABULATED CROSS SECTIONS WITH AND WITHOUT THE TAU HEAVY LEPTON CONTRIBUTION.
OBSERVATION OF J/PSI RESONANCE.
OBSERVATION OF PSI(3700)0 RESONANCE.
We have observed e + e − hadrons at C.M. energies of 13 GeV and 17 GeV at PETRA using the TASSO detector. We find R (13 GeV) = 5.6 ± 0.7 and R (17 GeV) = 4.0 ± 0.7. The additional systematic uncertainty is 20%. Comparing inclusive charged hadron spectra we observe scaling between 5 GeV and 17 GeV for x = p / p beam > 0.2; however the 13 GeV cross section is above the 17 GeV cross section for smaller x . This may be due to copious bb̄ production. The events become increasingly jet like at high energies as evidenced by a shrinking sphericity distribution with increasing energy.
TAU HEAVY LEPTON CONTRIBUTION SUBTRACTED.
THESE DATA FOR S*D(SIG)/DX AT 13 AND 17 GEV ARE INCLUDED IN THE RECORD OF R. BRANDELIK ET AL., PL 89B, 418 (1980).
Results on the hadronic final state in e/sup +/e/sup -/ annihilation at 13, 17 and 27.4 GeV are presented. There is no compelling evidence for the existence of the t quark in these data, which are in general agreement with a simple quark parton model. Some tentative indications of QCD effects are observed in the p/sub T//sup 2/ distributions.
TAU HEAVY LEPTON CONTRIBUTION SUBTRACTED.
INCLUSIVE HADRON SPECTRUM. THESE DATA AT 13, 17 AND 27.4 GEV ON S*D(SIG)/DX ARE INCLUDED IN THE RECORD OF R. BRANDELIK ET AL., PL 89B, 418 (1980).
None
CORRECTIONS HAVE BEEN APPLIED FOR CONTRIBUTIONS FROM BEAM-GAS SCATTERING, TWO PHOTON SCATTERING, TAU HEAVY LEPTON PAIR PRODUCTION, AND FOR RADIATIVE EFFECTS. THE 13 AND 17 GEV MEASUREMENTS WERE PREVIOUSLY REPORTED IN R. BRANDELIK ET AL., PL 83B, 261 (1979).
PRELIMINARY INCLUSIVE CHARGED PARTICLE DISTRIBUTIONS.
Measurements of energy-energy correlations in hadronic final states produced in e + e − annihilation at c.m. energies between 7.7 and 31.6 GeV are presented. The data are compared to perturbative QCD predictions. Good qualitative agreement above 20 GeV c.m. energy is found. The importance of non-perturbative effects is discussed, as well as the detailed behaviour of the correlation near 180°.
No description provided.
OPPOSITE SIDE ENERGY-ENERGY CORRELATIONS NEAR 180 DEG.
ENERGY-ENERGY CORRELATION INTEGRATED IN THE REGION 60 TO 120 DEG.
With a PETRA energy scan in ≤30-MeV steps, the continuum production of open top quark up to 38.54 GeV is excluded. Over regions of energy scan from 29.90 to 38.63 GeV limits are set on the product of hadronic branching ratio and electronic width BhΓee for toponium to be less than 2.0 keV at the 95% confidence level. By a search for flavor-changing neutral currents in b decay, models without a top quark are excluded.
MEASUREMENT OF R IN ENERGY SCAN FROM SQRT(S) = 29.9 TO 3.146 AND 33.0 TO 36.72.
MEASUREMENT OF R IN THE RANGE SQRT(S) 37 TO 38.63 GEV.
THRUST DISTRIBUTION FOR EVENTS IN THE RANGE SQRT(S) 37.94 TO 38.63 AND 38.54 TO 38.63.
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NUMBER OF K0S PER EVENT IN THE UPSILON REGION.
NUMBER OF ANTI(LAMBDA)S PER EVENT IN THE UPSILON REGION. FOR UPSI(4S) RESULTS SEE 'A'.
DSIG/DP DISTRIBUTIONS FOR K0 AND (ANTI) LAMBDA PRODUCTION AT THE UPSILON RESONANCES.
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DATA ARE CORRECTED FOR TWO-PHOTON AND TAU PRODUCTION EFFECTS, ACCEPTANCE AND QED RADIATIVE EFFECTS UP TO ORDER ALPHA**3. THERE IS ALSO A 6 PCT NORMALISATION ERROR NOT INCLUDED. THE OVERALL AVERAGE VALUE OF R FROM THIS DATA IS 3.88 +- 0.04 +- 0.22.
No description provided.
SEE PRL 55, 665 FOR MOST RECENT VALUES OF THE MU+ MU- CROSS SECTIONS.
We present the general properties of jets produced bye+e− annihilation. Their production and fragmentation characteristics have been studied with charged particles for c.m. energies between 12 and 43 GeV. In this energy rangee+e− annihilation into hadrons is dominated by pair production of the five quarksu, d, s, c andb. In addition, hard gluon bremsstrahlung effects which are invisible at low energies become prominent at the high energies. The observed multiplicity distributions deviate from a Poisson distribution. The multiplicity distributions for the overall event as well as for each event hemisphere satisfy KNO scaling to within ∼20%. The distributions ofxp=2p/W are presented; scale breaking is observed at the level of 25%. The quantityxpdδ/dxp is compared with multigluon emission calculations which predict a Gaussian distribution in terms of ln(1/x). The observed energy dependence of the maximum of the distributions is in qualitative agreement with the calculations. Particle production is analysed with respect to the jet axis and longitudinal and transverse momentum spectra are presented. The angular distribution of the jet axis strongly supports the idea of predominant spin 1/2 quark pair production. The particle distributions with respect to the event plane show clearly the growing importance of planar events with increasing c.m. energies. They also exclude the presence of heavy quark production,e+e−→Q\(\bar Q\) for quark masses up to 5<mQ<20.3 GeV (|eQ|=2/3) and 7<mQ<19 GeV (|eQ|=1/3). The comparison of 1/σtotdδ/dpT measured at 14, 22 and 34 GeV suggests that hard gluon bremsstrahlung contributes mainly to transverse momenta larger than 0.5 GeV/c. The rapidity distribution forW≧22 GeV shows an enhancement away fromy=0 which corresponds to an increase in yield of 10–15% compared to the centre region (y=0). The enhancement probably results from heavy quark production and gluon bremsstrahlung. The particle flux around the jet axis shows with increasing c.m. energy a rapidly growing number of particles collimated around the jet axis, while at large angles to the jet axis almost noW dependence is observed. For fixed longitudinal momentump‖ approximate “fan invariance” is seen: The shape of the angular distribution around the jet axis is almost independent ofW. The collimation depends strongly onp‖. For smallp‖,p‖<0.2 GeV/c, isotropy is observed. With increasingp‖ the particles tend to be emitted closer and closer to the jet axis.
R VALUES BELOW 32.5 GEV ARE IDENTICAL TO THOSE GIVEN IN BRANDELIK ET AL., PL 113B, 499 (1982).
No description provided.
CHARGED PARTICLE MULTIPLICITY DISTRIBUTIONS.
We have observed τ pair production at average CM energies of 13.9, 22.3, 34.5 and 43.1 GeV. The cross-sections are consistent with QED, the cut off parameters beingΛ+>161 GeV andΛ−169 GeV (95% CL). The topological branching fraction of the τ to 1 charged particle,B1, is 0.847±0.011 (stat)−0.013+0.016(syst) and no decays to 5 charged particles were observed resulting inB5<0.007 (95% CL). Within the 3 charged track final stateB(τ−→π−π+π−v)/(B(τ−→π−π+π−v)+B(τ−→π−π+π−π0v))=0.37−0.20+0.35
No description provided.
No description provided.
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