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Transverse Single-Spin Asymmetry and Cross-Section for $\pi^0$ and $\eta$ Mesons at Large Feynman-$x$ in Polarized $p+p$ Collisions at $\sqrt{s}=200$ GeV

The collaboration
Phys.Rev.D 86 (2012) 051101, 2012.

Abstract
Measurements of the differential cross-section and the transverse single-spin asymmetry, A_N, vs. x_F for pi0 and eta mesons are reported for 0.4 < x_F < 0.75 at an average pseudorapidity of 3.68. A data sample of approximately 6.3 pb^{-1} was analyzed, which was recorded during p+p collisions at sqrt{s} = 200 GeV by the STAR experiment at RHIC. The average transverse beam polarization was 56%. The cross-section for pi0 is consistent with a perturbative QCD prediction, and the eta/pi0 cross-section ratio agrees with previous mid-rapidity measurements. For 0.55 < x_F < 0.75, A_N for eta (0.210 +- 0.056) is 2.2 standard deviations larger than A_N for pi0 (0.081 +- 0.016).

• #### Figure 2 (c)

Data from Figure 2, pannel (c)

10.17182/hepdata.101343.v1/t1

(c) $A_N$ vs. $M_{\gamma\gamma}$ for the above mass distribution. The error bars are statistical uncertainties only.

• #### Figure 4 (up)

Data from Figure 4, upper pannel

10.17182/hepdata.101343.v1/t2

Differential production cross-sections for $\pi^0$ and $\eta$ at average pseudorapidity of 3.68. Also shown are the previously published STAR results...

• #### Figure 4 (bottom)

Data from Figure 4, bottom pannel

10.17182/hepdata.101343.v1/t3

The $\eta$ to $\pi^0$ cross-section ratio is shown in the bottom panel. The error bars indicate the total statistical and...

• #### Figure 5

Data from Figure 5

10.17182/hepdata.101343.v1/t4

$A_N$ vs. $x_F$ at average pseudorapidity of 3.68 for $\pi^0$ and $\eta$. Also shown are the previously published results for...