Sivers effect and the spin asymmetry in meson production

The transverse polarization of nucleon and the transverse momentum of its unpolarized constituent partons are correlated with each other. This can be fairly described by the Sivers effect. In recent years this effect is cynosure and produces privilege aspects from both theoretical and experimental views. To extend our knowledge from nucleon structure, this effect has an outstanding role. One way to obtain the Sivers function which is essentially depends on transverse momentum of partons, is to employ the Semi inclusive DIS (SIDIS) process. In this article a new parametrization for the concerned piece of Sivers function is used which is different with respect to what has been done in [M. Anselmino et al., Phys. Rev. D 72 (2005) 094007]. The required collinear PDF is getting from HERAPDF parametrization group. The unknown parameters which exist in Sivers function can be extracted, fitting the available experimental data for single spin asymmetry (SSA) in π+π− production. The final analytical results for SSA are in good agreement with the HERMES experimental data.