We present the fractional energy distributions for positive and negative hadrons produced in muon-proton and muon-neutron scattering, and ensuing charge ratios for the photon fragmentation region. Data presented for a center-of-mass energy range 2.8<W<4.5 GeV and a virtual-photon mass-squared range 0.5≤Q2≤4.5 GeV2 indicate an overall equality of summed structure functions for neutron and proton targets, which exhibit approximate independence of Q2 and ω′, Implications in terms of quark-fragmentation ideas are discussed.
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Measurements were made of the differential cross sections for the charge exchange of K − mesons on protons at momenta of 25 and 40 GeV/ c using a high-precision spectrometer with no magnetic field. In the range 5–40 GeV/ c the reaction cross section follows a power-law dependence p K − −1.52 . In the snall momentum transfer region (− t ⪅ m π 2 ) a minimum is observed, similar to that discovered at lower energies. The differential cross sections t = 0 are considerably less than those predicted by the Regge-pole model. The parameters of the effective trajectory are determined.
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Evidence is presented for the occurrence in e + e − annihilation of a new vector meson of mass 1821 ± 16 MeV and Γ = 31 ± 15 MeV.
MULTIHADRON EVENTS (AT LEAST THREE CHARGED TRACKS WITH ZERO OR MORE PHOTONS) PER UNIT LUMINOSITY.
We present experimental evidence for a resonant behaviour of the hadron production from e + e − annihilations at the e + e − storage ring ADONE. A Breit-Wigner fit to the enhancement present between 1800 and 1850 MeV gives the following parameters M = 1812 −13 +7 MeV, Γ = 34 −15 +21 MeV.
MULTIHADRON EVENTS (AT LEAST THREE CHARGED TRACKS) PER UNIT LUMINOSITY.
New experimental results are presented on proton-proton elastic scattering in the range of momentum transfer 4 GeV 2 < − t < 10 GeV 2 at the centre-of-mass energy of √ s = 53 GeV. The data have been obtained using the Split-Field Magnet detector at the CERN Intersecting Storage Rings. We observe another change of slope of the differential cross section near − t =6.5 GeV 2 .
NUMERICAL VALUES SUPPLIED BY K. WINTER.
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.
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SLOPE ABOUT 6 GEV**-2 FOR SMALL U AND EVIDENCE FOR CHANGE OF SLOPE NEAR -U = 0.15 GEV**2.
From the study of the reaction π − p→p F p p π − using a fast proton (p F ) trigger device in the CERN Omega spectrometer, we find evidence for two narrow p p states produced mainly in association with a Δ° (1232) and a N° (1520). The statistical significance of each peak is greater than 6 standard deviations. Masses and natural widths of these resonances are respectively M = 2020 ± 3 MeV , Λ 1 = 24 ± 12 MeV and M 2 = 2204 ± 5 MeV, Λ 2 = 16 −16 +20 MeV. Our data are consistent with a small production of the narrow ∼ 1935 MeV resonance already reported. Production cross sections for these new p p resonances are given.
ERRORS TAKE INTO ACCOUNT STATISTICAL ERRORS AND BACKGROUND SUBTRACTION UNCERTAINTY BUT NOT ACCEPTANCE CORRECTIONS UNCERTAINTY OF 15 PCT.
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A partial-wave analysis of the (3 π ) 0 system produced peripherally in the reaction K − p → π + π − π 0 Λ at 4.2 GeV/ c is presented. The observation of the weak Λ decay allows a determination of all the transversity production amplitudes except for two phases. The production of known resonances having decay modes other than 3 π is used to test the isobar model ansatz. Significant ω(783), φ(1020) and A 2 (1310) production is observed. The spin parity of the ω ∗ (1675) is established as 3 − . No evidence for production of other resonances, such as axial vector-mesons, is found.
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In this letter results are presented on the reactions K − p → K 0 n and K − p → K − p from a high statistics CERN 2-metre hydrogen bubble chamber exposure at 4.15 GeV/ c . The behaviour of the differential cross section as a function of four-momentum transfer shows remarkable similarities between the two reactions studied. From a comparison of our data with K + p elastic scattering at 4.27 GeV/ c we draw some conclusions concerning the magnitude of the contributing amplitudes.
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