The strong coupling constant, αs, has been determined in hadronic decays of theZ0 resonance, using measurements of seven observables relating to global event shapes, energy correlatio
Data corrected for finite acceptance and resolution of the detector and for intial state photon radiation. No corrections for hadronic effects are applied.. Errors include statistical and systematic uncertainties, added in quadrature.
Data corrected for finite acceptance and resolution of the detector and for intial state photon radiation. No corrections for hadronic effects are applied.. Errors include statistical and systematic uncertainties, added in quadrature.
Data corrected for finite acceptance and resolution of the detector and for intial state photon radiation. No corrections for hadronic effects are applied.. Errors include statistical and systematic uncertainties, added in quadrature.
The splitting processes in identified quark and gluon jets are investigated using longitudinal and transverse observables. The jets are selected from symmetric three-jet events measured in Z decays with the Delphi detector in 1991-1994. Gluon jets are identified using heavy quark anti-tagging. Scaling violations in identified gluon jets are observed for the first time. The scale energy dependence of the gluon fragmentation function is found to be about two times larger than for the corresponding quark jets, consistent with the QCD expectation CA/CF. The primary splitting of gluons and quarks into subjets agrees with fragmentation models and, for specific regions of the jet resolution y, with NLLA calculations. The maximum of the ratio of the primary subjet splittings in quark and gluon jets is 2.77±0.11±0.10. Due to non-perturbative effects, the data are below the expectation at small y. The transition from the perturbative to the non-perturbative domain appears at smaller y for quark jets than for gluon jets. Combined with the observed behaviour of the higher rank splittings, this explains the relatively small multiplicity ratio between gluon and quark jets.
Scaled energy distribution of charged hadrons produced in Quark jets in 'Y'topology 3-JET events.
Scaled energy distribution of charged hadrons produced in Gluon jets in 'Y'topology 3-JET events.
Scaled energy distribution of charged hadrons produced in Quark jets in 'Mercedes' topology 3-JET events.
We have observed ϱ 0 production in e + e − annihilation to hadrons at high energies. The differential cross section at a centre of mass energy W , of 34 GeV, is presented. In the range 0.2< x < 0.7, we measure 0.33 ± 0.06 (stat.) ± 0.07 (syst.), 0.22 ± 0.06 ± 0.05 and 0.22 ± 0.02 ± 0.05 ϱ 0 /event at W = 14, 22 and 34 GeV respectively.
No description provided.
No description provided.
INTEGRATION OVER RESTRICTED X RANGE.
The inclusive production of π ± mesons in e + e − annihilation has been measured at c.m. energies of 14, 22 and 34 GeV for pion momenta between 0.3 ans 10 GeV/ c . The fraction of pions among the charged hadrons is above 90% at 0.4 GeV/ c and decreases to about 50% at high momenta. The scaled cross sections ( s β ) d σ d x at 14, 22 and 34 GeV as well as the 5.2 GeV data from DASP have a rather similar x dependence. After integration over the x range from 0.2 to 0.6 the cross sections indicate a monotonic decrease with increasing centre-of-mass energy.
PION FRACTIONS IDENTIFIED BY INNER TOF COUNTERS (ITOF). ERRORS SHOWN ARE STATISTICAL ONLY.
PION FRACTIONS IDENTIFIED BY INNER TOF COUNTERS (ITOF). ERRORS SHOWN ARE STATISTICAL ONLY.
PION FRACTIONS IDENTIFIED BY INNER TOF COUNTERS (ITOF). ERRORS SHOWN ARE STATISTICAL ONLY.
Data on p and Λ production by e + e − -annihilation at CM energies between 30 and 36 GeV are presented. Indication for an angular anticorrelation in events with baryon-antibaryon pairs is seen.
No description provided.
No description provided.
AVERAGE NUMBER OF ANTIBARYONS PER HADRONIC EVENT. AN EXPONENTIAL SLOPE OF 2.5 GEV*-1 IN E WAS ASSUMED IN EXTRAPOLATING E*D3(SIG)/DP**3 TO ALL MOMENTA.
We have studied inclusive lepton production in e + e − annihilations into multihadrons in the energy range between √ s =50 and 55 GeV using the VENUS detector at TRISTAN, KEK. Though MARK-J and JADE groups at PETRA found an excess of isolated muon events at √ s ⩾46.3 GeV, we have not observed such an anomaly in muon nor in electron production. The observed rates of isolated leptons are consistent with the production and decay of five known quarks.
Observed rates for whole event sample.
No description provided.
No description provided.
D ∗± production via e + e − →D ∗± X has been measured at an average CM energy of 34.4 GeV. The D ∗± energy spectrum is hard, with a maximum near χ = 0.6. The size of the D ∗ cross section, R D ∗ = σ( e + e − → D ∗ X ) σ μμ = 2.50 ± 0.64 ± 0.88 (assuming R D ∗0 = R D ∗+ ) indicates that a large fraction of charm quark production yields D ∗ mesons. The D ∗± angular distribution exhibits a forward—backward asymmetry, A = −0.28 ± 0.13. This is consistent with that expected in the standard theory for weak neutral currents and leads to | g A c | = 0.89 ± 0.44 for the axial vector coupling of the charm quark.
ASSUMES EQUAL RATES FOR CHARGED AND NEUTRAL D*'S. ONLY CHARGED ARE DETECTED.
DATA PEAKS AT X=0.6 TO 0.8.
ASYMMETRY MEASUREMENT. THETA IS THE ANGLE BETWEEN THE E- AND THE D*.
We have studied at CM energies of 14, 22 and 30–36.7 GeV e + e − annihilation events in which the hadronic final state contains both a proton and an antiproton in the momentum range 1.0 < p < GeV/ c . We find that such pairs are produced predominantly in the same jet and conclude that baryon-antibaryon production is dominated by a mechanism involving local compensation of baryon number.
BACKGROUND SUBTRACTED DATA.
BACKGROUND SUBTRACTED DATA.
Evidence is presented for the occurrence in e + e − annihilation of a new vector meson of mass 1821 ± 16 MeV and Γ = 31 ± 15 MeV.
MULTIHADRON EVENTS (AT LEAST THREE CHARGED TRACKS WITH ZERO OR MORE PHOTONS) PER UNIT LUMINOSITY.
We present experimental evidence for a resonant behaviour of the hadron production from e + e − annihilations at the e + e − storage ring ADONE. A Breit-Wigner fit to the enhancement present between 1800 and 1850 MeV gives the following parameters M = 1812 −13 +7 MeV, Γ = 34 −15 +21 MeV.
MULTIHADRON EVENTS (AT LEAST THREE CHARGED TRACKS) PER UNIT LUMINOSITY.
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