Observation of asymmetry in inclusive proton production by 6-GeV/cpolarized protons

Left-right asymmetries of fast forward protons produced in the inclusive reaction $p_{\uparrow }p\to \mathrm{pX}$ have been measured using a 6-GeV/c polarized proton beam and the Argonne Effective Mass Spectrometer. The experiment covers the kinematic range $p_T^{}{}_{}{}^2\le 0.72$ ${\mathrm{GeV}}^2$ and $M_X\le 2.6$ GeV with 1.6 × ${10}^5$ inelastic events. The average asymmetry is 0.047 ± 0.010, with the same sign as the asymmetry in proton-proton elastic scattering and roughly half the magnitude. In order to facilitate comparison with future high-energy data in the triple-Regge region, finite-mass-sum-rule integrals are used to average over the low-$M_X$ data of this experiment.