Recent Results from Protvino Polarized Experiment Proza-M

TL;DR

This paper reports measurements of single spin asymmetries in proton-proton and pion-proton collisions at the Protvino accelerator, revealing negligible asymmetry in some reactions and significant asymmetry in others, with indications of energy dependence.

Contribution

The study provides new experimental data on single spin asymmetries at 70 GeV, highlighting reaction-specific behaviors and potential energy dependence of asymmetries.

Findings

Asymmetry in pp→pp is near zero at small |x_F| and low p_T.

Significant asymmetry (~-13.8%) observed in π−p→π−X at high |x_F|.

Asymmetry tends to increase with pion energy in the center of mass system.

Abstract

Single Spin Asymmetry $A_N$ (SSA) was measured at the Protvino 70 GeV accelerator. Asymmetry in the reaction $\ppdup$ is close to zero within error bars at small $|\xf|$ and $p_T<1.5$ GeV/c. SSA in the reaction $\pimp$ at polarized target fragmentation region equals to $(-13.8 \pm 3.8)%$ at $|x_f|>0.4$. There is an indication that the asymmetry begins to rise up at the same centre of mass system pion energy.