We present results on the production of high transverse momentum pizero and eta mesons in pi-p and pi-Be interactions at 515 GeV/c. The data span the kinematic ranges 1 < p_T < 11 GeV/c in transverse momentum and -0.75 < y < 0.75 in rapidity. The inclusive pizero cross sections are compared with next-to-leading order QCD calculations and to expectations based on a phenomenological parton-k_T model.
Invariant differential cross section per nucleon for inclusive PI0 production in PI- BE collisions at 515 GeV averaged over the cm rapidity interval -0.75 to 0.75.
Invariant differential cross section for inclusive PI0 production in PI- P collisions at 515 GeV averaged over the cm rapidity interval -0.75 to 0.75.
The averaged invariant differential cross section per nucleon as a functionof rapidity in the PT intervals 1.00 to 1.50 and 1.50 to 2.00 GeV for PI0 produ ction in PI- BE interactions at 515 GeV.
Measurements are reported of inclusive production of η-mesons in the beam fragmentation region in γp, πp andKp collisions. Results include a small but significant departure from VMD, and a pronounced rise in theη/π0 ratio with increasingpT.
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The inclusive production of vector mesons (charged ρ(770), ω(783), ϕ(1020) and neutralK*(892)) in π−p interactions at 360 GeV/c is studied. The data are based on 160 000 reconstructed events recorded in the NA 27 Experiment using the LEBC-EHS facility at CERN. The production cross sections in the forward hemisphere in c.m.s. and the longitudinal momentum distributions are determined. The results are compared with data obtained at lower energies.
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Upper limits of cross sections.
Cross sections extrapolated to x > 0.
The inclusive cross sections for η production by the interactions of 280 GeV/c momentum π−, π+, and proton beams in hydrogen have been measured. The kinematical range covered is −0.45<xF<0.45, and 4.0<PT<7.0 GeV/c for FeynmanxF and transverse momentum respectively. The η to π0 cross section ratios are given for the three reactions. The ratio of π−p to π+p cross sections for η production in the above kinematic ranges is 1.22±0.08±0.11.
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Theπ0 andη0 production is studied inπ−p interactions at 360 GeV/c. The cross section forπ0 production in the forward hemisphere (X>0) isσ(π0)=(49.7 ± 1.0 ± 1.1) mb and for η withX>0.1,Nch>2,σ(η0)=(3.1 ± 0.5) mb. The ratio of theπ0 toη0 cross section forX>0.1,Nch>2 isσ(π0)/σ(η0). Results on FeynmanX andpT distributions are presented. The data were obtained using the European Hybrid Spectrometer EHS and the bubble chamber LEBC at CERN.
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Neutral-pion production in 250-GeV/c π−p interactions are studied using the Fermilab 15-ft bubble chamber. The mean number of neutral pions produced is 3.54±0.15 per inelastic collision and a fit to a linear dependence on the charged multiplicity gives 〈n0〉=1.30+0.56n−. The π0 transverse- and longitudinal-momentum distributions are obtained from the inclusive γ-ray data and compared with the distribution obtained from those π0's which have both decay γ rays converting in the bubble chamber.
PI0 MEAN MULTIPLICITY IS OBTAINED FROM SIG(PI0,BACKGROUND CORRECTED)=70.8+-8.3 MB. THE NON-CORRECTED BACKGROUD SIG(PI0)=75.7+-3.2 MB AND < PI0 >=3.54+-0.15.
A clear, prompt dimuon signal has been observed in a low-statistics streamer-chamber experiment with 16-GeV/c πp interactions. The good mass resolution makes it possible to identify the contributions from ρ and ω decays and η and ω Dalitz decays. An excess of events is observed in the mass region ∼400-600 MeV which is not accounted for by the above-mentioned decays.
The data with PI+- beam obtained from the combination of PI+ and PI- beams.
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