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 present the results of a study of 1173 uniquely identified events of the K 0 π + p final state produced in 10 GeV/ c K + p interactions. This final state is dominated by the quasi two-body processes K + p → K 0 N ∗+ (890 p and K + p → K ∗+ (1420) p . The background is very low and there is little overlapping of resonance bands. We present cross sections, t -distributions and decay angular distributions for the contributing reaction channels. Dips are observed near t = 0 in the differential cross sections for all three processes.
BREIT-WIGNER FIT.
NUMERICAL VALUES TAKEN FROM THE COMPILATION LST7V2 FOX 72B.
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