We have measured π+p, π−p, and pp elastic scattering at an incident-beam momentum of 200 GeV/c in the region of −t, four-momentum transfer squared, from 0.021 to 0.665 (GeV/c)2. The data allow an investigation of the t dependence of the logarithmic forward slope parameter b≡(ddt)(lndσdt). In addition to standard parametrization, we use functional forms suggested by the additive quark model to fit the measured dσdt distributions. Within the context of this model we estimate the size of the clothed quark in the pion and proton. Limits on the elastic-scattering amplitude derived from unitarity bounds are checked, and no violations are observed.
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A comprehensive measurement of the differential cross section for π±p and pp elastic scattering has been made at large center-of-mass angles. π−p and pp scattering were measured with incident laboratory momenta ranging from 2 to 9.5 GeV/c. π+p scattering was measured with momenta from 2 to 6.3 GeV/c. Scattering angles were in the range −0.3≲cosθc.m.≲0.4. The results of the experiment are compared to constituent models and statistical models.
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We have measured the polarization in π − backward elastic scattering at 2.22, 2.46, 2.71 and 3.50 GeV/ c incident momenta, in the u -range−1.0 ≦ u ≦0.1 (GeV/ c ) 2 . The experiment used a polarized proton target and detected both pions and protons. We have found large discrepancies between the new data and the result of even the latest phase-shift analysis.
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Measurements of π±p backward elastic scattering have been made for incident pion momenta between 30 and 90 GeV/c and for 0<−u<0.5 (GeV/c)2. The momentum dependence of the cross sections is of a form expected from a simple Regge model, and the u dependence of the cross sections is similar to that observed at lower momenta.
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We present results from a high momentum resolution measurement of the π − p elastic differential cross section near the η production threshold. By analysing the cusp discontinuity in the elastic cross section we deduce the non-spin-flip elastic amplitude and compare it with solutions from phase-shift analyses.
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Measurements are reported of the differential cross section for the reaction π − +p→ ω +n from threshold to a final-state c.m. momentum P ∗ of 200 MeV /c . The previously reported fall in total cross section σ/P ∗ below about 100 MeV/ c is again seen. The differential cross section remains close to isotropic over the entire range. A paralle experiment on the variation in the elastic differential cross section across the threshold shows evidence of this threshold. The elastic data cover a range of incident moments from 1010 to 1180 MeV/ c in steps of 5 MeV/ c .
CROSS SECTION DEPENDENCE ON FINAL STATE CENTRE OF MASS MOMENTUM.
ANGULAR DISTRIBUTIONS ARE ALMOST ISOTROPIC.
LEGENDRE POLYNOMIAL COEFFICIENTS NORMALIZED SUCH THAT SIG = 4*PI*LEG(L=0).
We present a series of numerical and statistical techniques for interpolating and combining ("amalgamating") data from meson-nucleon scattering experiments. These techniques have been extensively applied to πp elastic and charge-exchange differential-cross-section and polarization data in the resonance region. The amalgamation is done by fitting a momentum- and angle-dependent interpolating surface to the data over a moderately narrow momentum range, typically ∼150 MeV/c, using the interpolating surface to shift data in a narrower central momentum region into fixed angular bins at a predetermined central momentum, and then statistically combining the data in each bin. The fitting procedure takes into account normalization errors, momentum calibration errors, momentum resolution, electromagnetic corrections, threshold structure, and inconsistencies among the data. The full covariance matrix of the amalgamated data is calculated, including contributions of statistical error, systematic error, and interpolation error. Techniques are presented for extracting from the covariance matrix information on the collective statistical fluctuations which correlate the errors of the amalgamated data. These fluctuations are described in terms of "correlation vectors" which facilitate the use of the amalgamated data as input for resonance-region phenomenology.
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The differential cross section has been measured at 30, 50, 80, 100, 120 and 140 GeV/ c for 0.002 < | t | < 0.04 ( GeV / c ) 2 . The results show that the π − p real part goes from negative to positive values below 80 GeV/ c . The slope parameter in the t -region measured is significantly higher than what has been found − t = 0.2 (GeV/ c ) 2 .
FROM FIT TO D(SIG)/DT AND SIGMA TOTAL FOR -T = 0.002 TO 0.04 (0.02 AT 30 GEV/C AND 0.03 AT 140 GEV/C) GEV**2.
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REAL/IMAG OF FORWARD AMPLITUDE FROM FIT TO D(SIG)/DT.
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