Single-Spin Asymmetry in Inclusive $\pi^0$ Production Measured at the Protvino 70 GeV Accelerator

TL;DR

This paper reports measurements of single-spin asymmetries in inclusive π^0 production at the Protvino 70 GeV accelerator, revealing near-zero asymmetry in proton-proton reactions and significant asymmetry in pion-proton reactions, with implications for understanding spin effects.

Contribution

It provides new experimental data on SSA in π^0 production at 70 GeV, highlighting differences between reactions and regions, contributing to spin physics knowledge.

Findings

SSA in p+p reactions is near zero.

SSA in π^-+p reactions reaches -15% in certain regions.

Asymmetry appears at similar pion energies in the center of mass frame.

Abstract

Single Spin Asymmetries (SSA) $A_N$ measured in the two reactions at the Protvino 70 GeV accelerator are presented. $A_N$ in the reaction $p+p(pol)->\pi^0+X$ in the central region is close to zero within the error bars. SSA in the reaction $\pi^- +p(pol)->\pi^0+X$ in the polarized target fragmentation region is equal to $(-15 \pm 4)%$ at $|x_F|>0.4$. There is an indication that the asymmetry arises at the same pion energy in the center of mass system.