Using the MD-1 detector at the VEPP-4e+e− strorage ring we have measured the inclusive Λ and370-1 production rates in direct Γ(1S) decays
Lambda x spectrum in direct upsilon(1S) decay.
Lambda multiplicity in direct upsilon(1S) decays.
Lambda multiplicity in surrounding continuum.
An analysis of the production of the Λ baryon in the hadronic decays of the Z 0 is presented, based on about 993K multihadronic events collected by the DELPHI detector at LEP during 1991 and 1992. The differencial cross section of the Λ and the correlations between Λ and Λ produced in the same event are compared to current models, based both on string fragmentation and on cluster decay. The predictions of the string fragmentation model are found to give satisfactory agreements with the data, clearly better than those of the cluster model.
No description provided.
Combined LAMBDA and LAMBDABAR multiplicity.
Errors contain systematic uncertainties.
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 measured the inclusive $D~{*\pm}$ production cross section in a two-photon collision at the TRISTAN $e~+e~-$ collider. The mean $\sqrt{s}$ of the collider was 57.16 GeV and the integrated luminosity was 150 $pb~{-1}$. The differential cross section ($d\sigma(D~{*\pm})/dP_T$) was obtained in the $P_T$ range between 1.6 and 6.6 GeV and compared with theoretical predictions, such as those involving direct and resolved photon processes.
Numerical values supplied by R. Enomoto.
No description provided.
Measurements of the forward-backward asymmetry of e + e − → cc events were carried out at a mean √s energy of 57.95 GeV at TRISTAN, KEK. The cc events were tagged either by the full-reconstruction of D ∗± or the inclusive P T spectrum of π s ± from D ∗± → D 0 ( D 0 )π s ± . The forward-backward asymmetry was measured to be A FB c = −0.49 −0.13 +0.14 (stat.) ± 0.06 (syst.), consistent with the standard model.
No description provided.
We have determined the strong coupling αs from measurements of jet rates in hadronic decays of Z0 bosons collected by the SLD experiment at SLAC. Using six collinear and infrared safe jet algorithms we compared our data with the predictions of QCD calculated up to second order in perturbation theory, and also with resummed calculations. We find αs(MZ2)=0.118±0.002(stat)±0.003(syst)±0.010(theory), where the dominant uncertainty is from uncalculated higher order contributions.
The second systematic error comes from the theoretical uncertainties.
The strong coupling constant α s was determined from analyses of the thrust, heavy jet mass and, differential 2-jet rate, using e + e - hadronic events at s = 58 GeV with the TOPAZ detector at TRISTAN. The NLLjet Monte Carlo simulation (NLLjet) and analytic formulae based on resummation up to the next-to-leading logarithms combined with O ( α 2 s ) calculations were used to evaluate α s . The average α s values at Q 2 = (58 GeV) 2 from the analyses are α s = 0.125 ± 0.009 for NLLjet and α s = 0.132 ± 0.008 for the resummed analytic formulae.
No description provided.
No description provided.
The exact definition for Y23 see text.
The production of $K^*+(892)$, $K^{*0}+(892)$, $\rho^{0}(770)$ and $\omega(783)$ vector mesons in $q\bar{q}$ events as well as in the gluonic $\Upsilon(1S)$ decays and $\Upsilon(4S) \to B\bar{B}$ decays has been studied using the ARGUS detector. Combining these results with data on pseudoscalar meson, $\phi$ meson and baryon production collected with the same detector allow comprehensive studies of quark and gluon fragmentation. Model independent information on $s$ quark and vector meson suppression $(s/u = 0.37 \pm 0.04, V/(V+P)_{\pi} = 0.21 \pm 0.04$ and $V/( V+ P)_K = 0.34 \pm 0.03))$ are derived. The data are compared with predictions from the models Jetset 7.3 and UCLA 7.31.
Vector meson multiplicities in the continuum region (sqrt(s) = 10.45 GeV). Data is also given for production of the pseudoscalar phi meson.
Vector meson multiplicities from Direct UPSI(1S) decays. Data is also givenfor production of the pseudoscalar phi meson.
Vector meson multiplicities from Direct UPSI(4S) decays. Data is also givenfor production of the pseudoscalar phi meson.
The first measurement of the neutron form factor in the time-like region has been performed by the FENICE experiment at the ADONE e + e − storage ring. Results at q 2 = 4.0 and 4.4 (GeV/ c ) 2 , together with a new measurement of the proton form factor are presented here.
Neutron form factor and cross section.
Preliminary analysis of proton form factor and cross section.
We measure the Drell-Yan differential cross section d2σdMdy||y|<1 over the mass range 11<M<150 GeV/c2 using dielectron and dimuon data from p¯p collisions at a center-of-mass energy of s=1.8 TeV. Our results show the 1M3 dependence that is expected from the naive Drell-Yan model. In comparison to the predictions of recent QCD calculations we find our data favor those parton distribution functions with the largest quark contributions in the x interval 0.006 to 0.03.
Dielectron differential cross section.
Dimuon differential cross section.
Drell-Yan differential cross section for combined dielectron and dimuon data. Error includes both statistics and systematics.
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