In π − p interactions at 9 GeV/ c and 12 GeV/ c , the forward production of N ∗ 1680 and N ∗ 1520 has been observed with features of nucleon exchange. The production of Δ1232 is strongly suppressed.
None
Results are presented on the topological cross sections obtained for antiproton-proton interactions from an exposure of the Fermilab 30-inch bubble chamber to a 100 GeV/ c negative beam enriched in p 's. The p p inelastic cross section is found to be σ inel = 34.6 ± 0.4 mb, and the average inelastic charged particle multiplicity to be 〈 n 〉 = 6.74 ± 0.05.
Inclusive cross sections for π 0 , K s 0 , Λ 0 and Λ 0 production in 100, 200 and 360 GeV /c π − p interactions are presented and compared with data at other energies. Invariant cross sections for γ, K s 0 , Λ 0 and Λ 0 production are presented in terms of Feynman x , the rapidity y , and transverse momentum squared, p T 2 . A comparison of the observed γ spectrum is made with the spectra computed assuming that the π 0 momentum distribution is identical to that of the observed π + or π − .
The results are presented of two partial-wave analyses of the (3π) − system in 30 000 events of the reaction π − p → π − π − π + p at 11.2 GeV/ c . Both techniques incorporate the assumptions of the isobar model and are (a) the University of Illinois program which fits in terms of the (3π) density matrix elements and (b) an amplitude parametrisaton including possible effects of both spin non-flip and spin flip at the baryon vertex. The results obtained with these independent programs are found to be very close.
We present a study of antineutrino interactions in hydrogen obtained in a 138000-picture run at the BNL 7-ft bubble chamber. The antineutrino beam had an energy distribution that peaked at ∼1.1 GeV. The cross section measured for charged-current interactions is σ(ν¯p→μ++anything)=(0.32±0.08)×10−38×[Eν¯ (GeV)] cm2. The neutral-current cross section is σ(ν¯p→ν¯pπ+π−)=5.5−2.6+4.4×10−40 cm2. The ratio of strangeness-changing to non-strangeness-changing charged currents is Rs=0.06−0.05+0.13. An upper limit determined for charm production is σc<3.8×10−40 cm2 at the 90% confidence level. From the momentum-transfer distribution we measure average Q2 for inelastic charged-current events with energy greater than 2 GeV, 〈Q2〉=(0.10±0.03)[Eν¯ (GeV)]+(0.10±0.09) (GeV/c)2. Using a maximum-likelihood method we determine from the quasielastic events ν¯p→μ+n an axial-vector mass MA=0.9−0.3+0.4 GeV/c2.
We have measured the forward production spectra of various neutral particles produced by π−, K−, p¯, and p at 200 GeV/c, and by π− at 290 GeV/c incident on a Be target. The salient features of these measurements are (1) copious production of KSo at large Feynman xL for incident π− and K−, (2) production of roughly equal fluxes of Λ0 and Λ¯0 for incident π−, and (3) close similarity of the following spectra: π−→n and K−→Λ0; π−→Λ0, π−→Λ¯0, and p→KS0; π−→KS0 and p→Λ0. The overall features of the various distributions seem to agree with the ideas of dimensional counting presented in the constituent-interchange model of quark collisions. Results are presented in terms of the invariant cross section Ed3σ(xL, PT=0)dp3 per Be nucleus for each inclusive reaction.
We present measurements of the differential and polarization cross sections for the reactions KL0p→Ks0p, Λπ+, Σ0π+, and Λπ+π0 made in a hydrogen bubble chamber exposed to a beam of KL0 with incident momentum 550±35 MeV/c. The quasielastic data imposes additional constraints on the partial-wave analyses of the KN and K¯N systems. Our data show no strong energy-dependent effects in the region of the reported Σ(1580), JP=32− state. The phase of the forward regeneration amplitude was found to be about - 160° independent of KL0 momentum.
We have measured the cross section, the distribution of scattering angles, and the distribution of noncoplanarity angles for electron-positron elastic scattering at 5 GeV c. m. energy. An analysis based on 230 events with scattering angles between 50 and 130° yields a ratio of the experimental to theoretical quantum-electrodynamic cross section of 1.03 ± 0.09. The scattering-angle and noncoplanarity-angle distributions are also found to be in excellent agreement with the quantum-electrodynamic predictions.
Inclusive production of Λ0 hyperons by 300-GeV protons has been measured at fixed production angles in the laboratory between 0 and 9 mrad and laboratory momenta from 65 to 300 GeV/c. Three different solid targets were used: beryllium, copper, and lead. The A dependence of the data is suggestive of a collision model in which the hadron loses energy and gains transverse momentum as it leaves the nucleus. The experimental results are compared to such a model, and the implications are discussed.
Forum