Single spin asymmetry measurements for $\pi^0$ inclusive productions in $p+p_{\uparrow} \to \pi^0 + X$ and $\pi^-+\p_{\uparrow}\to \pi^0+X$ reactions at 70 and 40 GeV respectively

TL;DR

This study measures the single spin asymmetries in inclusive neutral pion production for proton and pion beams at 70 and 40 GeV, finding asymmetries near zero in some regions and increasing with _x_F in others, providing insights into spin effects in hadron collisions.

Contribution

First measurements of   asymmetries at these energies in specified kinematic regions, expanding understanding of spin asymmetries in hadron production.

Findings

Asymmetry is compatible with zero at central rapidity.

Asymmetry increases with _x_F for .4 < x_F < -0.1.

Average asymmetry in certain kinematic interval is about -13.8%.

Abstract

The inclusive $\pi^0$ asymmetries were measured in reactions $p+p\uparrow \to \pi^0+X$ and $\pi^-+p\uparrow \to \pi^0+X$ at 70 and 40 GeV/c respectively. The measurements were made at the central region (for the first reaction) and asymmetry is compatible with zero in the entire measured $p_T$ region. For the second reaction the asymmetry is zero for small $x_F$ region ($-0.4<x_F<-0.1, 0.5<p_T(GeV/c) <1.5$) and increases with growth of $\mid x_F\mid$. Averaged over the interval $-0.8<x_F<-0.4, 1<p_T(GeV/c)<2$ the asymmetry was $-(13.8\pm 3.8)%$.