We report results from a measurement of the inclusive diffraction dissociation of photons on hydrogen, γp→Xp, in the range 75<pγ<148 GeV/c, 0.02<‖t‖<0.1 (GeV/c)2, and MX2/s<0.1. Our data show an exponential t dependence and a dominant 1/MX2 behavior for MX2>4 GeV2. We test the finite-mass sum rule and, by comparing γp with π−p data obtained in the same apparatus, we test factorization.
EXTRACTED ELASTIC CROSS SECTIONS.
RESULTS OF EXPONENTIAL FITS TO ELASTIC CROSS SECTIONS.
EXPONENTIAL FITS TO THE INELASTIC CROSS SECTIONS.
In a single-arm spectrometer experiment, high-precision measurements of dσdt for π−p, K−p, and p¯p elastic scattering have been made at 8 and 16 GeV/c. The π−p data show rich structure at 8 GeV/c, indicative of strong non-Pomeron contributions, while the 16-GeV/c data are much smoother. For −t≳1 (GeV/c)2 there is a strong s dependence while there is very little for −t<1 (GeV/c)2. For p¯p scattering the forward region is smoothly diffractive for −t<0.4 (GeV/c)2 and shows antishrinkage. The exponential slope parameter b is measured to be 12.36 ± 0.04 (GeV/c)−2 at 8 GeV/c and 11.40 ± 0.04 (GeV/c)−2 at 16 GeV/c. The structure near −t=0.6 (GeV/c)2 seen at lower energies is still obvious at 16 GeV/c. The K−p data show some structure at 8 GeV/c, but can be represented adequately by a quadratic exponential form. At 16 GeV/c the K−p angular distribution shows antishrinkage and lies above the 8-GeV/c cross section for 0.11<−t<0.8 (GeV/c)2.
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Measurements of K − p elastic scattering have been carried out at 14 momenta between 610 MeV/ c and 943 MeV/ c over the angular range −0.9 < cos θ < 0.9. The results agree well with the best existing data and have significantly smaller errors.
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DIFFERENTIAL CROSS SECTION AT 0 DEG CALCULATED FROM DISPERSION RELATIONS AND AT 180 DEG INTERPOLATED FROM BUBBLE CHAMBER MEASUREMENTS.
LEGENDRE POLYNOMIAL FIT, INCLUDING FORWARD AND BACKWARD POINTS.
Elastik K − n ( I = 1) differential cross sections have been measured at 14 momenta between 610 and 940 MeV/ c , over the c.m. angular range −0.7 < cos θ ∗ < 0.8 . The results, which cover the c.m. energy range 1610–1765 MeV, have been fitted with Legendre polynomials and compared with some existing predictions from a partial-wave analysis.
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Measurements of K + p elastic scattering have been carried out at 13 momenta between 432 MeV/ c and 939 MeV/ c using spark chambers. The data establish unambiguously the constructive interference of the Coulomb and nuclear amplitudes at 432 MeV/ c . The elastic cross section is found to be independent of momentum through the range covered. The phase shifts for S, P, D and F waves are obtained in an energy dependent analysis in which higher waves are held at theoretical values. The initial behaviour ofthe P, D and F amplitudes is quite close to that predicted by the calculation of the peripheral partial waves. Only the P3 and D5 amplitudes become strikingly different with increasing momentum.
COULOMB INTERFERENCE EFFECT SEEN AT SMALL ANGLES.
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We present data from a spark-chamber study of K+p elastic scattering between 432 and 939 MeV/c, over the range −0.6<cosθc.m.<+0.7. With measurements at 13 momenta, and between 2000 events at the lowest momentum and 5000 events at the highest momentum, there is a major improvement over previous data. The elastic cross sections deduced from the differential cross sections are almost independent of momentum through the range covered. The data are inconsistent with counter measurements of the total cross section which suggest a sharp shoulder in the cross section at about 700 MeV/c.
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Differential cross sections have been measured for nucleon-isobar production and elastic scattering in p−p interactions from 6.2 to 29.7 GeVc in the laboratory angle range 8<θsc<265 mrad. N*' s at 1236, 1410, 1500, 1690, and 2190 MeV were observed. Computer fits to the mass spectra under varying assumptions of resonance and background shapes show that conclusions on t and s dependence are only slightly affected despite typical variations in absolute normalization of ± 35%. Logarithmic t slopes in the small- |t| range are ∼15 (GeVc)−2 for the N*(1410), ∼5 (GeVc)−2 for the N*'s at 1500, 1690, and 2190 MeV, and ∼9 (GeVc)−2 for elastic scattering. Also for the small- |t| data, cross sections for N*'s at 1410, 1500, 1690, and 2190 MeV and for elastic scattering vary only slightly with Pinc consistent with the dominance of Pomeranchuk exchange and with diffraction dissociation. A fit of N*(1690) total cross sections to the form σ∝P−n gives n=0.34±0.06, while for elastic scattering n=0.20±0.05. For the N*(1690) the effective Regge trajectory has the slope αeff′(0)=0.38±0.17. When compared with N* production in π−, K−, and p¯ beams these data also agree with approximate factorization of the Pomeranchuk trajectory. N*(1236) cross sections are consistent with other measurements at similar momenta. For −t>1 (GeVc)−2, elastic scattering cross sections decrease approximately as Pinc−2, and they and N*(1500)− and N*(1690)− production cross sections have t slopes consistent with 1.6 (GeVc)−2.
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