The elastic photoproduction of four pions has been studied at incident photon energies between 2.8 and 4.8 GeV. Production cross-sections are presented and an analysis of the angular decay correlations is also described, indicating a large 1− contribution in both final states, π+ π− π+ π− and π+ π− π0 π0. A quantitative understanding of these and other available 4π photoproduction data in terms of the ρ′(∼1.2GeV) and the ρ′(∼1.6) is presented.
WITH OMEGA/RHO DECAY PARAMETRIZATION.
WITH OMEGA/A1 DECAY PARAMETRIZATION.
We present a study of the inclusive production ofK*(892) and ∑t+-(1385)+cc at 3.6 GeV/c from\(\bar p\)p interactions. The sensitivity of the exposure is 35.4 events/μb. Longitudinal and transverse momentum distributions are presented. The indirect production ofKs0 from parentK* and that of Λ's from parent Σ(1385) are studied. The shape of thex distribution of Λ's for\(p\xrightarrow{{\bar p}}\Lambda \) are calculated from\(p\xrightarrow{p}\Lambda \) and\(p\xrightarrow{{\pi ^ -}}\Lambda \) and compared with the experimental distributions. The difference of antiparticle production cross-section ofKs0 in the central region is compared with the expectation from Mueller-Regge formalism.
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Measurements of π±p backward elastic scattering have been made for incident pion momenta between 30 and 90 GeV/c and for 0<−u<0.5 (GeV/c)2. The momentum dependence of the cross sections is of a form expected from a simple Regge model, and the u dependence of the cross sections is similar to that observed at lower momenta.
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This paper reports on the first results of the study of e+e− collisions at s=27.4 GeV and s=27.7 GeV at PETRA, using the 4π-sr electromagnetic and calorimetric detector MARK-J. We obtain an average R=σ(e+e−→hadrons)σ(e+e−→μ+μ−)=3.8±0.3 (statistical)±0.6 (systematic) and a relative R=1.0±0.2 between the two energies. The R values, the measured thrust distribution, and average spherocity show no evidence for the production of new quark flavors.
THE RELATIVE VALUE OF R BETWEEN THESE TWO ENERGIES IS 1.0 +- 0.2.
THRUST DISTRIBUTION (1/N)*DN/DTHRUST AT 13, 17 AND 27 GEV. THESE DATA ARE RATHER DETECTOR DEPENDENT.
We present high-statistics results on the reactions a+p→c+X where a and c can be any of π±, K±, p, or p¯. The data were taken at 100 and 175 GeV/c incident momenta using the Fermilab Single-Arm Spectrometer operated over the kinematic range 0.2<x<1.0 and pt<~1.0 GeV/c. Investigating the x dependence of the data, we find agreement with a quark-parton picture, namely the cross sections have a power-law behavior in 1−x independent of pbeam and pt.
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We report experimental results on the cross section for the reaction e + e − → hadrons as a function of the total c.m. energy in the range W = 1.42–3.09 GeV. The results, combined with those already existing below the charm threshold, clearly indicate a structure for R ( W ) = α ( e + e − → hadrons)/ α ( e + e − → μ + μ − ) in that energy region.
THE ENERGY RANGES OF THE NEW DATA AND THE PREVIOUS (REVISED) DATA OVERLAP BETWEEN 1.9 AND 2.0 GEV. RADIATIVE CORRECTIONS HAVE BEEN APPLIED TO ALL DATA. THIS CROSS SECTION EXCLUDES TWO-BODY FINAL STATES.
AVERAGE CHARGED AND NEUTRAL MULTIPLICITY. QUOTED ERRORS ARE STATISTICAL ONLY.
Measurements have been made of the double polarisation parameters G and H in the photoproduction of neutral pions from protons, for incident photon energies between 1300 MeV and 2300 MeV and for pion c.m. angles between 50δ and 80δ. The results are compared with predictions from a recent comprehensive analysis of earlier photoproduction data.
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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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We present measurements of the cross section for inclusive D and K meson production in e + e − annihilation in the center of mass energy range 3.6 to 5.8 GeV. D production accounts for most of the increase in the total cross section for hadron production in e + e − annihilation at energies above 4 GeV.
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Data on inclusive jet production in the transverse-momentum (p⊥) range 0-8 GeV/c for 200-GeV/c p, π−, π+, K−, K+, and p¯ incident on a hydrogen target are presented. The jet cross section is fully corrected for losses and biases, and compared with the predictions of a model based on quantum chromodynamics. Both the absolute cross section and the inclusive charged-particle distributions inside and outside the jet are in qualitative agreement with the model.
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