Detect Gluon Polarisation at BNL-RHIC Through J/\psi Pair Production   Process
  Our recent study shows that the double spin asymmetry of J/\psi pair production is measurable in polarised p-p collision at RHIC in near future. And hence it enables us to extract the polarised gluon distribution function \Delta G (x). 
Jiro Kodaira and Cong-Feng Qiao