pi^0 Transverse Single-Spin Asymmetries at eta=4.1 in p+p Collisions at sqrt{s}=200 GeV

TL;DR

This paper reports on measurements of the transverse single-spin asymmetry for pi^0 production at high Feynman-x and low transverse momentum in proton-proton collisions at 200 GeV, providing insights into spin effects in forward particle production.

Contribution

It extends previous measurements of A_N to lower p_T and higher x_F regions, offering new data to understand spin asymmetries in forward pi^0 production.

Findings

Asymmetry does not decrease at low p_T as previously expected.

Extended data at x_F > 0.4 and p_T ~ 1 GeV/c.

Preliminary results suggest persistent large asymmetries.

Abstract

Large transverse single-spin asymmetries, A_{N}, have been observed in forward hadron production at RHIC. STAR has reported precision measurements of the x_{F}-p_{T} dependence of A_{N} for forward pi^0 production. Contrary to expectation, the asymmetry does not fall with p_{T}. However, questions remain about the trend at the lower end of the studied range, p_{T}~1 GeV/c. Analysis of data from the 2008 RHIC run has extended the pi^0 data in the x_{F} > 0.4, low p_{T} region. Preliminary results are reported.