Non-resonant Production Research Articles

Deep-inelastic electron scattering from carbon

We have measured the deep-inelastic electron scattering from carbon up to and including the Δ-region at 36°, 60°, 90° and 145°. The systematic decomposition of the transverse and longitudinal response functions has been obtained by means of a Rosenbluth-type analysis of the data in the momentum transfer interval 200 MeV/c /s | q| /s 600 MeV/c. A comparison with theoretical calculations which extend over the quasielastic and Δ-peak regions is presented. A reduction of the differences between our data and theory seems obtainable through the introduction of meson-exchange currents, resonant and non-resonant meson production, and the use of the shell model. Our experimental Coulomb sum-rule estimates at higher | q| agree with independent particle model predictions. We compare our results in the vicinity of the Δ-peak with the total absorption cross section for real photons.

Inclusive hadron production in the ϒ-region

Inclusive production of π ±, K ± and p has been measured in e +e − annihilation for center of mass energies between 9.4 and 10.1 GeV. The hadron yields on the resonances ϒ and ϒ' are compared to the off-resonance (continuum) yields with the aim of uncovering differences between three-gluon hadronization and quark-antiquark fragmentation. A noticeable differences is seen in the yield of protons and antiprotons which is (8.1 ± 2.1)% of all charged hadrons for ϒ decay and (18.9 ± 6.9)% of ϒ' decay compared to (1.5 ±1.1.)% for non-resonant production.

Two-component model for lepton-pair production inπ−Ncollisions

Nonresonant lepton-pair production in pion-nucleon collisions is analyzed in terms of a two-component model. Results are compared with experimental data.

DiffractiveA1production by neutrinos

A phenomenological study of diffractive $\ensuremath{\pi}\ensuremath{\rho}$ production by neutrinos in the ${A}_{1}$ region is performed. The difference between resonant and nonresonant (Deck-type) production is worked out. Interference effects are included. Numerical results for the mass and decay angular distributions are given.

Charged pion, kaon and nucleon production by e +e − annihilation for c.m. energies between 3.6 and 5.2 GeV

Inclusive production of ifπ ±, K ± and p has been studied near charm threshold for c.m. energies between 3.6 and 5.2 GeV. Differential and scaling cross sections together with particle multiplicities have been determinated. By comparing data below and above charm threshold the charm contribution to if π ± and K ± production has been extracted. A comparison has been made between inclusice p production and inelastic electron-proton scattering. To study differences between three-gluon annihilation and two-quark production of the spectra from J/ decay and from non-resonant production at 3.6 GeV has been compared.

Search for Photoproduction of Bosons by the Missing-Mass Technique and Measurement of thesandtDistribution of the Photoproduced Hadronic Continuum

The reaction gamma + p yields p + m/sup o/ was studied with a tagged- photon beam of energy range 1.90 to 4.70 GeV. No new resonances were seen in the state m/sup o/ but instead a large nonresonant production was observed. The s and t dependence of this continuum production were measured and found to have interesting properties. The recoil-proton spectra from the photoproduced continuum are found to strongly resemble recoil-proton spectra from hadron- initiated reactions. (auth)

Measurements of Inelastic Electron Scattering Cross Sections near the One-Pion Threshold

The cross sections for single-arm inelastic electron-proton scattering were measured near the one-pion threshold for six values of ${q}^{2}$ between 0.23 and 1.84 Ge${\mathrm{V}}^{2}$. We determined the cross sections for nonresonant pion production and, using a particular formulation of soft-pion theory, extracted the normalized axial-vector form factor of the nucleon, $\frac{{G}_{A}({q}^{2})}{{G}_{A}(0)}$.

Mass dependence of slopes in multiparticle production

The multiple-scattering theory is extended to investigate multiparticle production from complex targets. It is found that the slopes for resonant and nonresonant multiparticle production from protons (treated as composite systems) are very nearly equal, in agreement with experimental findings, and predictions about possible variations of the slopes as a function of mass are made.

Gamma ray cascades in O 15

The gamma rays from the reaction N 14(p, γ)O 15∗ have been investigated over the proton energy range from 950 to 1560 keV. It is found that the 8.29-MeV level (1060-keV resonance) in O 15 cascades weakly through a level at 7.17 MeV and through the known level at 6.15 MeV, in addition to the transitions already known to the 5.2-MeV levels and the ground state. The radiative widths of the 8.29-MeV level for transitions to the ground state, 5.2-MeV levels, 6.15-MeV level, and 7.17-MeV level are respectively 0.54 eV, 0.33 eV, 0.06 eV and 0.02 eV. The non-resonant production of O 15 in the above proton energy range is almost entirely accounted for by a transition through the 6.79-MeV level in O 15. At the 8.75-MeV level (1550-keV resonance) the transitions to the ground state, 5.2-MeV states, 6.8-MeV states, and 7.17-MeV state all appear to be weakly resonant.