Single-spin asymmetry in inclusive reactions $p_{\uparrow }$+p→${\pi }^{+}$+X, ${\pi }^{\mathrm{-}}$+X, and p+X at 13.3 and 18.5 GeV/c

Data are presented for the left-right asymmetry in inclusive production of ${\pi }^{+}$, ${\pi }^{\mathrm{-}}$, and p with proton beams (polarized normal to the scattering plane) of 13.3 and 18.5 GeV/c incident on a ${\mathrm{LH}}_2$ target. At both energies the asymmetry in ${\pi }^{+}$ production grows steadily to about 25% near the kinematic limit, whereas the ${\pi }^{\mathrm{-}}$ and p asymmetries are consistent with zero over the measured range of $p_t$, 1.1–2.2 GeV/c.