Gluon Sivers Function and Single Spin Asymmetry in $e+p^\uparrow   \rightarrow e+J/\psi + X$
  We propose measurement of transverse single spin asymmetry (SSA) in charmonium production as a probe of gluon Sivers function. We estimate SSA in low virtuality electroproduction of $J/\psi $ using color evaporation model of charmonium production and existing models of the gluon Sivers function and find sizable asymmetry at JLab, HERMES, COMPASS and eRHIC energies. 
Rohini M. Godbole, Anuradha Misra, Asmita Mukherjee, Vaibhav S. Rawoot
hep-ph hep-ex