We report a study of 20 exclusive reactions measured at the AGS at 5.9 GeV/c incident momentum, 90° center of mass. This experiment confirms the strong quark flow dependence of two-body hadron-hadron scattering at large angle. At 9.9 GeV/c an upper limit had been set for the ratio of cross sections for (p¯p→p¯p)(pp→pp) at 90° c.m., with the ratio less than 4%. The present experiment was performed at lower energy to gain sensitivity, but was still within the fixed angle scaling region. A ratio R(p¯ppp)≈140 was measured at 5.9 GeV/c, 90° c.m. in comparison to a ratio near 1.7 for small angle scattering. In addition, many other reactions were measured, often for the first time at 90° c.m. in the scaling region, using beams of π±, K±, p, and p¯ on a hydrogen target. There are similar large differences in cross sections for other reactions: R(K−p→π+Σ−K−p→π−Σ+)≈112, for example. The relative magnitudes of the different cross sections are consistent with the dominance of quark interchange in these 90° reactions, and indicate that pure gluon exchange and quark-antiquark annihilation diagrams are much less important. The angular dependence of several elastic cross sections and the energy dependence at a fixed angle of many of the reactions are also presented.
Cross sections at 90 degrees in the centre-of-mass.
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We report on a measurement of elastic differential cross sections for p±p, π±p, and K±p at 100 and 200 GeV/c in the range 0.03<|t|<0.10 (GeV/c)2. Our data display a simple exponential dependence which is consistent with other measurements in this t region or with extrapolations from higher t.
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We present preliminary results on the measurement of a variety of exclusive hadron interactions at center of mass scattering angles of 90°. Data are also presented which show the relative transparency of nuclei to πp and pp elastic scattering in this kinematic range.
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We give cross sections for annihilation and non-annihilation reactions in p p interactions at 8.8 GeV. The non-annihilation data are compared with pp data from the same experiment. We compare data on resonance production and on the impact parameter structure of the final states in p p annihilation and non-annihilation and pp interactions. We investigate the charge structure of the 2 π + 2 π − π 0 final state, and find it consistent with a simple quark model.
NORMALIZED TO A TOTAL P P CROSS SECTION OF 40.0 MB.
We report final results on the polarization parameter P in elastic scattering of π − , K − and antiprotons at 40 GeV/ c incident momentum. The energy dependence of P (t) in π − p above 10 GeV/ c is well fitted by P (t) α s αR(t)-α P (t) where α R (t) are the effective Regge and Pomeron trajectories respectively. The data in K − p are compatible with exchange degeneracy. The results inp¯p show an important structure for |t|> 0.3 (GeV/c) 2 demonstrating the existence of a large helicity flip amplitude.
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We have measured the elastic cross section for pp, p¯p, π+p, π−p, K+p, and K−p scattering at incident momenta of 70, 100, 125, 150, 175, and 200 GeV/c. The range of the four-momentum transfer squared t varied with the beam momentum from 0.0016≤−t≤0.36 (GeV/c)2 at 200 GeV/c to 0.0018≤−t≤0.0625 (GeV/c)2 at 70 GeV/c. The conventional parametrization of the t dependence of the nuclear amplitude by a simple exponential in t was found to be inadequate. An excellent fit to the data was obtained by a parametrization motivated by the additive quark model. Using this parametrization we determined the ratio of the real to the imaginary part of the nuclear amplitude by the Coulomb-interference method.
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The differential cross sections for elastic π − p, K − p , p p and π + p, pp scattering at 39 and 44.5 GeV/ c , respectively, have been measured in the interval of momentum transfer squared 0.15 ≤ ovbt | ≤ 2 (GeV/ c ) 2 .
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Results are presented from experiment WA7 at the CERN SPS, which has measured the elastic differential cross sections of π ± p, K ± p, p p and pp at incident momen ta of 20, 30 and 50 GeV/ c . The measurements cover the momentum transfer range 0.5 < | t | < 8 (GeV/ c ) 2 , corresponding to c.m. scattering angles between 10° and 50°. The experimental set-up, trigger logic and data analysis are described. The experimental results are compared with existing meson-proton and nucleon-proton data at lower and higher energies covering the medium- and large-| t | region. Some prominent models and their predictions for elastic scattering at WA7 energies and beyond are reviewed, with emphasis on geometrical scaling, factorizing eikonal models, lowest-order QCD and other dynamical exchange-type models. Results for p p two-body annihilation into π − π + and K − K + at 30 and 50 GeV/ c , obtained in parallel with the elastic p p data, are also presented.
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A description is given of an experiment to study elastic scattering of π ± , K ± and p on protons at c.m. scattering angles from 45° to 100° at incident laboratory momenta 20 GeV/ c and 30 GeV/ c . The corresponding t range is from −6.2 (GeV/ c ) 2 to −28 (GeV/ c ) 2 . There are no previous observations for these reactions in this t range. High intensity and large geometrical acceptance were required in order to measure the low cross sections. The experiment used a double-arm spectrometer. MWPCs were used for reconstruction, and threshold and differential Čerenkov counters for identification. Scintillation counters, Čerenkov counters and a hadron calorimeter were used in the trigger. The trigger logic utilized specially designed matrices and a hard wired microprocessor. The π − p elastic scattering cross sections follow approximately the dimensional counting rule from 3.5 GeV/ c .and up to 30 GeV/ c . The cross sections decrease by seven orders of magnitude in this energy range. The data is compared to quark models. None of these models give a comprehensive description of the results. However, some modifications to these models improve their consistency with the data.
EARLIER RESULTS GIVEN IN 'A'.
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EARLIER RESULTS GIVEN IN 'A'.
We present results of measurements of K ± p and p p elastic scattering and of the annihilation reactions p p →π + π − and p p → K + K − at an incident laboratory momentum of 5 GeV/ c . Nearly complete angular distributions were obtained. Results are also presented for π -meson proton elastic scattering in the momentum transfer ranges 2 < − t < 8 (GeV/ c ) 2 (for π + ) and 0.16 < − t < 7 (GeV/ c ) 2 (for π − ). All measurements were done in one experimental geometry. The measured differential cross sections range from 10 to 10 −5 mb/(GeV/ c ) 2 .
-U = T + 8.486 GEV**2.
THE DATA FOR -T = 7.31 TO 8.45 GEV**2 WERE NORMALIZED TO OTHER EXPERIMENTS.
-U = T + 8.304 GEV**2.
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