The properties of the final-state hadronic system in antineutrino-proton charged-current interactions are presented. The events were observed in the Fermilab 15-foot hydrogen bubble chamber. The average energy of the events is ∼30 GeV, but there are some interactions beyond 100 GeV. The mean multiplicity of the charged hadrons varies as 〈nCH〉=(0.06±0.06)+(1.22±0.03)lnW2 for hadronic masses W in the range 1.0<W2<50 GeV2. By contrast, the multiplicity depends only weakly on the four-momentum transfer between the leptons. The mean pion multiplicities for events with three or more charged tracks are found to be 〈n−〉=1.64±0.04, 〈n0〉=1.16±0.13, for π− and π0 production, respectively. By comparing the number of positive tracks with π− data from neutrino production, we deduce a mean proton multiplicity 〈np〉 of 0.53 ± 0.15. The single-particle distributions in both longitudinal and transverse momentum are found to be similar to those for nondiffractive production in hadronic collisions. The fragmentation properties of the final-state d quarks are compared to the expectations of the quark-parton model. The fraction of observed neutral-strange-particle production for events with three or more charged tracks is 0.08 ± 0.015 and is consistent with coming completely from associated production.
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This paper gives a detailed description of an experiment which studies the interactions of muon-type neutrinos in hydrogen and deuterium. The experiment was performed at the Zero Gradient Synchrotron using the wide-band neutrino beam incident on the Argonne 12-foot bubble chamber filled with hydrogen and deuterium. The neutrino energy spectrum peaks at 0.5 GeV and has a tail extending to 6 GeV. The shape and intensity of the flux is determined using measurements of pion yields from beryllium. The produced pions are focused by one or (for the latter part of the experiment) two magnetic horns. A total of 364000 pictures were taken with a hydrogen filling of the bubble chamber and 903 000 with a deuterium filling. The scanning and other analyses of the events are described. The most abundant reaction occurs off neutrons and is quasi-elastic scattering νd→μ−pps. The separation of these events from background channels is discussed. The total and differential cross sections are analyzed to obtain the axial-vector form factor of the nucleon. Our result, expressed in terms of a dipole form factor, gives an axial-vector mass of 0.95±0.09 GeV. A comparison is made to previous measurements using neutrino beams, and also to determinations based upon threshold pion electroproduction experiments. In addition, the data are used to measure the weak vector form factor and so check the conserved-vector-current hypothesis.
Measured Quasi-Elastic total cross section.
The cross sections for the line-reversed reaction pairs K+n→K0p and K−p→K¯0n, and K+p→K0Δ++ and K−n→K¯0Δ− have been determined with high statistics and good relative normalization at 8.36 and 12.8 GeV/c in a spectrometer experiment at Stanford Linear Accelerator Center. The cross sections for the K+-induced reactions are larger than for the K−, contrary to the expectations of weakly-exchange-degenerate Regge-pole models. The ratio of the reaction cross sections is about the same as at lower energies and shows little change with momentum transfer.
Axis error includes +- 11/11 contribution.
Axis error includes +- 11/11 contribution.
Axis error includes +- 11/11 contribution.
We have measured the invariant cross section for inclusive ϕ production in proton-nucleus collisions at 400 GeV/c near Feynman x=0. For transverse momenta in the range between 0.8 and 3.5 GeV/c the ratio of ϕ to π− rises from 1 to 7%. We also report on correlations with particles opposite the ϕ in the center-of-mass system as they relate to the Okubo-Zweig-Iizuka rule.
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The multiplicity distribution of inclusive electron events above 4 GeV cm energy shows two distinct classes of events: two prong no photon and high multiplicity events. If the high multiplicity events are attributed to the semi-leptonic decay of charmed particles the two prong no photon events must come from the weak decay of a different type of particle. The charged K to π ratio was measured for these events. The average number of charged kaons is 0.07 ± 0.06 per two prong event and 0.90 ± 0.18 per multiprong event. Thus the weak current responsible for the low multiplicity events has a small coupling to strange particles.
NUMBER OF CHARGED PARTICLES OBSERVED .EQ. 2.
NUMBER OF CHARGED PARTICLES OBSERVED .GE. 3.
Differential cross sections have been measured in the region of small forward angles (between 0 and ∼40 mrad) for the elastic scattering reactions pp → pp at 4.2, 7.0 and 10.0 GeV /c and p p → p p at 4.2, 6.0, 8.0 and 10.0 GeV /c . The maximum momentum transfer is ∼0.025 GeV 2 at the lowest and ∼0.10 GeV/c at the highest incident momentum. Values of the slope and the real part of the forward scattering amplitude of the above reactions have been derived; the values obtained are in good agreement with dispersion relations.
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Results are presented on the inclusive reactions p p → K 0 X , p p → Λ X and p p → Λ X at an incident antiproton momentum of 12 GeV/ c in BEBC. The cross sections are studied as functions of the Feynman scaling variable x , the rapidity, the transverse momentum of the V 0 and the missing mass squared. The dependence of the Λ and Λ polarization on x are also studied. Comparisons with proton-proton data at 12 GeV/ c are also made. Finally, events with two detected V 0 are analyzed in order to study correlations arising from the production of two strange neutral particles.
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We observe a resonance in the total cross section for hadron production in e+e− annihilation at a mass of 3772±6 MeV/c2 having a total width of 28±5 MeV/c2 and a partial width to electron pairs of 370±90 eV/c2.
BEFORE ANY RADIATIVE CORRECTIONS.
AFTER APPLYING ALL RADIATIVE CORRECTIONS.
We present the first direct measurements of charged-particle multiplicity distributions for pp collisions at ISR energies. The measurements are performed by means of a streamer chamber detector with large solid-angle coverage and excellent multitrack efficiency. Particle densities are observed to rise in the central region as s increases. The multiplicity distributions in this region deviate from a Poisson Law, thus giving evidence for correlations. These correlations are of the same type as those obtained from clustering of the collision products. The mean charged multiplicity over the full rapidity range increases faster than log s . Our data do not support an early onset of KNO multiplicity scaling.
Pseudorapidity distribution at 23.6 GeV.
Pseudorapidity distribution at 45.2 GeV.
Pseudorapidity distribution at 62.8 GeV.
A spin-parity 1 + ϱπ enhancement is observed for the 3π mass spectrum in the reaction K − p → Σ − π + π + π − where events with a small (K − → Σ − ) momentum transfer are selected. The mass (1040 MeV) and width (230 MeV) of this enhancement are reminiscent of the A 1 → ϱπ bump which has mainly been observed in the diffractive-like processes. The cross section for this enhancement at 4.15 GeV/ c incident K − momentum is (3.6 ± 0.5) μ b.
No description provided.
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