Single Spin Asymmetries in Heavy Quark and Antiquark Productions

Abstract

The single transverse spin asymmetries in heavy quark and anti-quark production from the quark-antiquark annihilation channel contribution is studied by taking into account the initial and final state interactions effects. Because of the different color charges, the final state interaction effects lead to about a factor of 3 difference in the spin asymmetry for heavy quark over that for the anti-quark in the valence region of low energy pp collisions. The experimental study of this model-independent prediction shall provide a crucial test for the underlying mechanism for the single spin asymmetry phenomena.

Figures (4)

• Figure 1: Initial/final state interactions contributions to the SSAs in heavy quark and antiquark productions: (a) initial state interaction with color strength $1/2N_c$; (b) final state interaction on the quark line with color strength $(N_c^2-2)/2N_c$; (c) final state interaction on the antiquark line with color strength $2/2N_c$. The mirror diagrams where the gluon attaches to the right of the cut line are not shown, but also contribute.
• Figure 2: Single spin asymmetries for charm quark and anticharm quark production in $p^\uparrow p$ scattering at JPARC energy: as functions of rapidities with $P_\perp$ integrated out (left panel); and as functions of transverse momentum $P_\perp$ with $y_{c.m.}>0$ (right panel).
• Figure 3: Single spin asymmetries for charm and anticharm quark production in $p^\uparrow \bar{p}$ scattering at $\sqrt{s}=14GeV$ at PAX energy region: as functions of raptidities with $P_\perp$ integrated out (left panel); as functions of charm quark transverse momentum $P_\perp$ with $y_{c.m.}>0$ (right panel).
• Figure 4: Ratio of the SSA for the charm quark over that for the anticharm quark as function of charm quark rapidity in $p^\uparrow p$ scattering at JPARC (left) and $\bar{p}^\uparrow p$ scattering at PAX (right) experiments.