Measurement of the analyzing power for p+$p_{\uparrow }$→p+p at $P_{\perp }$${\mathrm{}}^2$=6.5 (GeV/c${)}^2$

The spin analyzing power A in 28-GeV/c proton-proton elastic scattering was measured at $P_{\perp }$ ${\mathrm{}}^2$=6.5 (GeV/c${)}^2$ using a polarized proton target and a high-intensity unpolarized proton beam at the Brookhaven National Laboratory Alternating Gradient Synchrotron. The result of (24±8)% confirms that the analyzing power is large and rising in the large-$P_{\perp }$ ${\mathrm{}}^2$ region.