Accessing transversity via J/Psi production in polarized p-pbar interactions

Abstract

We discuss the possibility of a direct access to transversity distributions by measuring the double transverse spin asymmetry A_TT in p pbar --> J/Psi + X --> l^- l^+ + X processes at future GSI-HESR experiments with polarized protons and anti-protons. In the J/Psi resonance production region, with 30 < s < 45 GeV^2, both the cross-section and A_TT are expected to be sufficiently large to allow a measurement of h_1^q(x,M^2); numerical estimates are given.

Figures (2)

• Figure 1: The $p \bar{p}$ Drell-Yan double transverse spin asymmetry $\tilde{A}_{TT}^{p \bar{p}}(M^2, x_F)$ as a function of $x_F$, for $M = 4$ GeV/$c^2$ (solid curve: $s=45$ GeV$^2$; dashed curve: $s = 30$ GeV$^2$).
• Figure 2: The double transverse spin asymmetry $\tilde{A}_{TT}^{J/\psi}$ for $J/\psi$ production in $p \bar{p}$ collisions, as a function of $x_F$ at $M = 3$ GeV/$c^2$ (solid curve: $s=45$ GeV$^2$; dashed curve: $s = 30$ GeV$^2$).