- By:
- Lajoie, John G; Novitzky, Norbert ; Read Jr, Kenneth F
- Journal Name:
- Physical Review D
- Page Number:
- 72006-72006
- Volume:
- 113
- Issue Number:
- 7
- Publication Date:
- June 16, 2026
- View DOI Listing:
- https://doi.org/10.1103/6vnq-5hfx
Abstract
Utilizing the 2012 transversely polarized proton data from the Relativistic Heavy Ion Collider at Brookhaven National Laboratory, the forward 𝜂-meson transverse single-spin asymmetry (𝐴𝑁) was measured for 𝑝↑+𝑝 collisions at √𝑠 =200 GeV as a function of Feynman-x (𝑥𝐹) for 0.2 <|𝑥𝐹| <0.8 and transverse momentum (𝑝𝑇) for 1.0 <𝑝𝑇 <5.0 GeV/𝑐. Large asymmetries at positive 𝑥𝐹 are observed (⟨𝐴𝑁⟩=0.086±0.019), agreeing well with previous measurements of 𝜋0 and 𝜂 𝐴𝑁, but with reach to higher 𝑥𝐹 and 𝑝𝑇. The contribution of initial-state spin-momentum correlations to the asymmetry, as calculated in the collinear twist-3 framework, appears insufficient to describe the data.
