Measurement of the analyzing power in inclusive, high-x(F) neutral pion production at 185 GeV/c

[摘要] The analyzing power, A, in inclusive $pisp0$ production by a polarized proton beam at 185 GeV/c was found to be 0.10 $pm$ 0.03 for $langle$x$sb{m F}angle$ = 0.52 and $langle$p$sb{m T}angle$ = 0.8 Gev/c. The $pisp0$'s were detected using a combined lead-glass, lead-scintillator photon absorption calorimeter constructed at the Bonner Lab. Using a simple parton recombination model applied to spin parameter measurements, A$sb{m N}$ = 0.19 $pm$ 0.02 for this reaction. Since the measured A is consistent with this model, it suggests that the leading quark in a high energy scattering reaction retains the transversity of the incident proton. This can be generalized to suggest that a valence quark model can be used to describe the spin of the proton in certain kinematic regions. A polarized antiproton beam was also produced and A was observed to be nonzero but with low statistics due to short running time. These results show that spin effects continue to be present and have importance at the highest measured energies.

[发布机构] Rice University

[效力级别] physics