The Fermilab hybrid 30-in. bubble-chamber spectrometer was exposed to a tagged 147-GeV/c positive beam containing π+, K+, and p. A sample of 3003 K+p, 19410 pp, and 20745 π+p interactions is used to derive σn, 〈n〉, f2cc, and 〈nc〉D for each beam particle. These values are compared to values obtained at other, mostly lower, beam momenta. The overall dependence of 〈n〉 on Ea, the available center-of-mass energy, for these three reactions as well as π−p and pp interactions has been determined.
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The charged multiplicity has been measured at the ϒ(4S) and a value of 5.75±0.1±0.2 has been obtained for the mean charged multiplicity in B-meson decay. Combining this result with the measurement of prompt leptons from B decay, the values 4.1±0.35±0.2 and 6.3±0.2±0.2 are found for the semileptonic and nonleptonic charged multiplicities, respectively. If b→c dominance is assumed for the weak decay of the B meson, then the semileptonic multiplicity is consistent with the recoil mass determined from the lepton momentum spectrum.
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The energy dependence of the average of the charged multiplicity and its dispersion in π + /K + /p interaction on protons at 147 GeV/ c is found to be the same as in e + e − annihilations if an “effective energy” variable is used instead of the total energy. The effective energy S eff is defined as the invariant mass of all secondaries left after the two leading particles have been removed. Fitting the expression aS eff b to the average charge multiplicity 〈 n ch 〉, we find the power b to be in good agreement with the value of 0.25 predicted by Fermi's statistical model and by Landau's hydrodynamical model.
BINS IN WEFF SELECTED SO AS TO YIELD 200 EVENTS IN EACH BIN.
200 EVENTS IN EACH BIN IN WEFF.
50 EVENTS IN EACH BIN IN WEFF.
Multiplicity distributions and correlations between charged particles in the forward and back-ward c.m. hemispheres are studied inK−p interactions at 110 GeV/c and compared with other data on mesonnucleon scattering. The interpretation in terms of a simple quark-parton picture assuming that the forward multiplicity is dominated by quark fragmentation and the backward multiplicity by diquark fragmentation is supported by the experimental fact that the forward and the backward mean multiplicities are approximately equal to half of thee+e− andpp multiplicities, respectively. The 110 GeV/cK−p data show significant correlations between the numbers of slow forward and slow backward particles, whereas the multiplicities of fast forward and fast backward particles are independent.
CHARGED MULTIPLICITY PER INELASTIC EVENT.
NONDIFFRACTIVE SAMPLE ( -0.85 < XL < 0.85 ). CHARGED MULTIPLICITY PER INELASTIC EVENT.
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.
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We present data on\(\bar pn\) and π− n collisions obtained from an exposure of the 30′' FNAL deuterium filled bubble chamber to a mixed\({{\bar p} \mathord{\left/ {\vphantom {{\bar p} {\pi ^ -}}} \right. \kern-\nulldelimiterspace} {\pi ^ -}}\) beam with a momentum of 100 GeV/c. We find that in 17±2% of the collisions with the antiproton there is an interaction on the spectator while for the collisions with π− mesons the corresponding number is 15±2%. The\(\bar pn\) and π− n multiplicity distributions have average charged multiplicities of 6.46±0.07 and 6.53±0.08 respectively. The average multiplicities for both types of interactions are slightly smaller than those for the corresponding reactions on hydrogen by an amount that is the same as observed at other energies. As an estimate of\(\bar pn\) annihilation we have calculated the difference\(\sigma _n (\bar pn) - \sigma _n (pn)\) for each prong numbern. We find an average multiplicity of 9±1, a value close to that for\(\bar pp\) annihilation at the same energy. combining our data with lower energy\(\bar pn\) annihilation data, we observe that the average negative multiplicity is systematically larger than that for\(\bar pp\) annihilation similar to the difference between neutron and proton target data with other beam projectiles.
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The charged multiplicity distribution is presented for K − p interactions produced in the hydrogen bubble chamber, BEBC, using an r.f. separated, tagged K − beam of 110 GeV/ c momentum. A comparison with K + p, πp and pp data at lower energies shows that the main features of the multiplicity distributions depend on energy and charge of the incident particles, but not on their strangeness. At high energies, only the energy is important.
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Measurements of the charged multiplicities for hadron production in e + e − annihilation in the center of mass energy range 9–32 GeV have been made. The average charged multiplicity has an energy dependence much stronger than ln s and similar to that reported for pp collisions. Quantitative differences are observed in the magnitude of both the average multiplicity 〈 n ch 〉 and the dispersion D ch for e + e − and pp interactions at the same center of mass energy. 〈 n ch 〉 and the ratio 〈 n ch / D ch in e + e − annihilations are significantly larger than in pp collisions and are found to be in overall agreement with QCD predictions. KNO scaling is seen to be satisfied.
THE FINAL TABLE ENTRY COMBINES THE DATA FROM THE THREE HIGHEST ENERGY BINS.
Cross sections and charged multiplicity distributions forK+p interactions at 70 GeV/c are presented and compared withK+p data at other energies. Comparisons are also made with available π+p,pp, andK−p data.
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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.
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