Comparison of 20 exclusive reactions at large<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>t</mml:mi></mml:math>

We report a study of 20 exclusive reactions measured at the AGS at 5.9 GeV/c incident momentum, 90\ifmmode^\circ\else\textdegree\fi{} 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 $\frac{(\overline{p}p\ensuremath{\rightarrow}\overline{p}p)}{(pp\ensuremath{\rightarrow}pp)}$ at 90\ifmmode^\circ\else\textdegree\fi{} 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 $R(\frac{\overline{p}p}{pp)}\ensuremath{\approx}\frac{1}{40}$ was measured at 5.9 GeV/c, 90\ifmmode^\circ\else\textdegree\fi{} 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\ifmmode^\circ\else\textdegree\fi{} c.m. in the scaling region, using beams of ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$, ${K}^{\ifmmode\pm\else\textpm\fi{}}$, $p$, and $\overline{p}$ on a hydrogen target. There are similar large differences in cross sections for other reactions: $R(\frac{{K}^{\ensuremath{-}}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\Sigma}}^{\ensuremath{-}}}{{K}^{\ensuremath{-}}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\Sigma}}^{+}})\ensuremath{\approx}\frac{1}{12}$, for example. The relative magnitudes of the different cross sections are consistent with the dominance of quark interchange in these 90\ifmmode^\circ\else\textdegree\fi{} 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.