Charged hadron production ine+e− annihilation is studied in the 7 to 10 GeV CM energy region and at the Υ (9.46) and Υ′ (10.01) resonances with the LENA detector at DORIS. The statistical moments of the charged multiplicities are studied. The data show KNO scaling behaviour and suggest the presence of long range correlations. An average charged multiplicityrise of Δn(Υ)=0.55±0.19 and Δn(Υ′)=1.26±0.29 over the continuum is observed for the Υ and Υ′ direct decays. The jet structure of the Υ and Υ′ direct decays is investigated using the charged particles. The polar angular distributions of the jet axis behave like 1+α(T) cos2θ with 〈α(T)〉Υ=0.7±0.3 and 〈α(T)〉Υ′=0.6±0.4. The 〈α(T)〉Υ value is in agreement with the QCD vector gluon assignment and excludes scalar gluons by more than four standard deviations.
No description provided.
No description provided.
No description provided.
The resonance parameters of the ϒ′(10.01) were measured using the LENA detector at the DORIS e + e − storage ring. We obtained a mass of M ( ϒ ′) = (10 013.6 ± 1.2 ± 10.0) MeV and an electronic width of Γ ee ( ϒ ′) = (0.53 ± 0.07 −0.05 +0.09 keV. The upper limit set to the μ-pair branching ratio is 3.8% which implies a lower limit on the total ϒ′ width of 14 keV. Together with out previous measurement of the ϒ parameters we obtain a mass difference M(ϒ′) − M(ϒ) = (552.0 ± 1.3 ± 10.0) MeV and Γ ee (ϒ′) Γ ee (ϒ) = 0.43 ± 0.07 −0.00 +0.05 .
HADRONIC CROSS SECTION IN REGION OF UPSI(10020)0.
With use of the LENA detector at the DORIS e+e− storage ring, the hadronic cross section and the μ-pair decay branching ratio of the ϒ(9.46) resonance have been measured. Γee=1.23±0.10 (±0.14) keV, Bμμ=[3.5±1.4 (±0.4)]%, and Γtot=35−10+25 ({+9}{−7}) keV have been obtained. The first set of errors gives the statistical uncertainty. The numbers in parentheses represent systematic errors arising from the uncertainty in the total hadronic cross section.
No description provided.
We employ data taken by the JADE and OPAL experiments for an integrated QCD study in hadronic e+e- annihilations at c.m.s. energies ranging from 35 GeV through 189 GeV. The study is based on jet-multiplicity related observables. The observables are obtained to high jet resolution scales with the JADE, Durham, Cambridge and cone jet finders, and compared with the predictions of various QCD and Monte Carlo models. The strong coupling strength, alpha_s, is determined at each energy by fits of O(alpha_s^2) calculations, as well as matched O(alpha_s^2) and NLLA predictions, to the data. Matching schemes are compared, and the dependence of the results on the choice of the renormalization scale is investigated. The combination of the results using matched predictions gives alpha_s(MZ)=0.1187+{0.0034}-{0.0019}. The strong coupling is also obtained, at lower precision, from O(alpha_s^2) fits of the c.m.s. energy evolution of some of the observables. A qualitative comparison is made between the data and a recent MLLA prediction for mean jet multiplicities.
Overall result for ALPHAS at the Z0 mass from the combination of the ln R-matching results from the observables evolved using a three-loop running expression. The errors shown are total errors and contain all the statistics and systematics.
Weighted mean for ALPHAS at the Z0 mass determined from the energy evolutions of the mean values of the 2-jet cross sections obtained with the JADE and DURHAMschemes and the 3-jet fraction for the JADE, DURHAM and CAMBRIDGE schemes evaluted at a fixed YCUT.. The errors shown are total errors and contain all the statistics and systematics.
Combined results for ALPHA_S from fits of matched predicitions. The first systematic (DSYS) error is the experimental systematic, the second DSYS error isthe hadronization systematic and the third is the QCD scale error. The values of ALPHAS evolved to the Z0 mass using a three-loop evolution are also given.
We have measured the absolute cross section σ(θ) and complete sets of spin observables A00ij in He3(p,p) elastic scattering at energies of 200 and 500 MeV. The observables depend on linear combinations of six complex scattering amplitudes for the p−3He system and provide a severe test of current reaction models. The in-scattering plane observables (A00mm, A00ll, A00lm, and A00ml) are all in quantitative disagreement with fully microscopic nonrelativistic optical model calculations and nonrelativistic distorted wave Born approximation calculations.
A00N0 is analyzing power.
A00N0 is analyzing power.
A00NN is spin correlation parameter.
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.
An experimental investigation of the structure of identified quark and gluon jets is presented. Observables related to both the global and internal structure of jets are measured; this allows for test
The measured jet broadening distributions (B) in quark and gluon jets seperately.
Measured distributions of -LN(Y2), where Y2 is the differential one-subjet rate, that is the value of the subjet scale parameter where 2 jets appear from the single jet.
The mean subjet multiplicity (-1) for gluon jets and quark jets for different values of the subject resolution parameter Y0.
Using data from the NA32 experiment at CERN we have studied the Λ + c decays containing a Σ + among the decay products. The interactions of 230 GeV π − with a Cu target were analysed using a precise vertex telescope (charge-coupled devices and silicon microstrip detectors) and the ACCMOR spectrometer. We have found eleven Λ + c →Σ + π + π − , one Λ + c →Σ + K + K − , two Λ + c →Σ + K + π − and one Λ + c →Σ + π + π − π + π − decays practically without any backgroun d. We have measured the branching ratios with respect to the Λ + c →pK − π + channel.
No description provided.
We have observed four unambiguous decays of the charmed strange baryon Ξ c o in the NA32 experiment at CERN. Charge- coupled devices and silicon microstrip detectors were used to reconstruct the decay mode Ξ c o → pK − K ∗ (892) o seen in events produced by the interaction of 230 GeV/ c negative poins and kaons on a copper target. We present the first measurement of the lifetime of the Ξ c o , together with a determination of its mass and production cross section. The resonant components of the Ξ c o decay are studied. We use our earlier measurement of the mass of the Ξ c + in the determination of the isospin mass splitting of the Ξ c states.
No description provided.
We have observed six unambiguous decays of the charmed strange baryon Ξ c + (or charge conjugate Ξ c − ) in the 230 GeV/c negative pions or kaons on a copper target at the CERN SPS using silicon microstrip detectors and charge-coupled devices for vertex reconstruction. Three of them have been reconstructed through the decay chain Ξ c + → Ξ − π + π + , Ξ − → Λ 0 π − , Λ 0 → pπ − and the other three through the decay chain Ξ c + → Σ + K − π + → pπ 0 . We present our measurements of the mass, lifetime and production cross-section of the Ξ c + , as well as of the branching ration for the two decay modes.
The cross sections times branching ratio, linear A-dependence is assumed.
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