This paper presents production and decay characteristics of 500 high-mass, high-resolution μ+μ− pairs produced in π− Be collisions at 150 and 175 GeV/c. The data do not agree with a simple Drell-Yan production mechanism, but indicate that higher-order quantum-chromodynamic corrections must be included.
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Final data on topological cross sections are presented. Inclusive single particle distributions for the reactionsK+p→ π±X at 32 GeV/c are discussed and compared with data at lower energies. Early scaling in the fragmentation regions is confirmed, while cross sections in th central region continue to rise with energy even faster than inpp interactions. Thex-andpT-dependence of the π+/π− ratio inK+p interactions is discussed and a comparison of reactionsK+p→ π±X andK−p→ π±X at 32 GeV/c is made in the context of constituent models. We also present transverse momentum distributions, show prominent seagull effects and study how they are influenced by resonance production.
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Inclusive production of Δ ++ (1232) with >| t p, Δ ++>|<0.6 (GeV/ c ) 2 is studied in 32 GeV/ c K + p interactions. A systematic comparison with the reaction K + p→pX for >| t p,p>| < 0.6 (GeV/ c ) 2 is made. The production properties of the Δ ++ (1232), of associated π + , π − and K 0 production and of the recoiling system X 0 are investigated in detail. The polarization of the Δ ++ and the energy dependence of the total K + π − cross sections, determined by a Chew-Low extrapolation, are presented and discussed.
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We present new data on charged particle production in p p interactions at 100 GeV/ c . Comparisons are made between p p annihilations (estimated by differences) between corresponding p p and pp data samples) and e + e − annihilation into hadrons. A technique for separating the inclusive proton and pion spectra is described and the resulting pion spectra are studied in terms of Feynman x , rapidity and p T . Comparison with pp data allows us to estimate the pion spectra in p p annihilations and we find agreement with predictions of Mueller-Regge theory. We also present results on semi-inclusive π ± and proton production, give updated topological cross sections and describe further attempts to isolate effects due to annihilations. Finally we investigate the diffractive excitation of the antiproton into low-mass states by studying events with a slow recoil proton.
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Inclusive and semi-inclusive cross sections for gp0 production in 100, 200, and 360 GeV/c π−p interactions are presented. Differential cross sections for ρ0 production as functions of c.m. rapidity and transverse momentum are compared with the corresponding differential cross sections for pion production. Effects of various methods of estimating background on the values obtained for ρ0 production cross sections are discussed. About 10% of the final-state charged pions appear to come from ρ0 decay. Thus, while ρ0 production and decay is a significant source of final-state pions, other sources must contribute the majority of the produced pions.
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Inclusive and semi-inclusive distributions of γ's and π 0 's in the reactions K + p → γ + X and K + p → π 0 + X at 32 GeV/ c are presented and discussed. When compared to the inclusive π − production, the π 0 cross section is found to be significantly higher in low | x | and p T regions. The data are compared with other experiments and quark fusion model predictions.
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ESTIMATED FROM GAMMA AND 2GAMMA SPECTRA.
At the CERN intersecting storage ring the inclusive differential cross section [dσdσ]y=1 has been measured for f0, g0, K*0(1420), and K¯*0(1420) production: We obtain 0.58±0.05 mb, 0.09±0.05 mb, 38±15 μb, and 26±13 μb, respectively. The corresponding total inclusive cross sections are estimated to be 2.62±0.26 mb, 0.40±0.22 mb, 154±60 μb, and 107±52 μb, respectively. The magnitude of the K* cross section implies a cross section of approximately 5 μb for production of a charmed DD¯ pair.
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We present results on inclusive Δ ++ (1236) production in 100 GeV/ c p p interactions. In the region | t | < 1 GeV 2 we find a cross section of 1.29 ± 0.15 mb. Comparisons with pp interactions at high energies show Δ ++ production in pp and p p interactions to be very similar. The decay angular distributions of the Δ ++ are consistent with production predominantly through pion-exchange and the properties of the system recoiling from the Δ ++ are similar to those of real π + p interactions. However, the p π + background is found to show qualitatively similar behaviour. In contrast to the indications of Δ ++ production through pion exchange we also find evidence that events proceeding through diffraction dissociation are more likely to contain Δ ++ than other events. We present results on the forward production of Δ ++ in association with Δ ++ and protons.
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Inclusive single-particle spectra for π± production are presented for data from π±p interactions at 100 GeV/c. The spectra for the four reactions π±p→π±+anything are compared as a function of laboratory longitudinal momentum, Feynman x, center-of-mass (c.m.) rapidity, and transverse momentum squared. Comparisons are also made between these data and analogous data from 16 and 18.5 GeV/c π±p interactions and the energy dependence is discussed. Average values of the transverse momentum are given as a function of the longitudinal momentum and charged-particle multiplicity. A comparison of the charge distributions is presented as a function of rapidity and c.m. energy.
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