Transverse Single Spin Asymmetries and Charmonium Production

We estimate transverse spin single spin asymmetry(TSSA) in the process e+p↑→J/ψ+X using color evaporation model of charmonium production. We take into account transverse momentum dependent(TMD) evolution of Sivers function and parton distribution function and show that the there is a reduction in the asymmetry as compared to our earlier estimates wherein the Q2 – evolution was implemented only through DGLAP evolution of unpolarized gluon densities.