Process dependent Sivers function and implications for single spin asymmetry in inclusive hadron production

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We study the single transverse spin asymmetries in the single inclusive particle production within the framework of the generalized parton model (GPM). By carefully analyzing the initial- and final-state interactions, we include the process-dependence of the Sivers functions into the GPM formalism. The modified GPM formalism has a close connection with the collinear twist-3 approach. Within the new formalism, we make predictions for inclusive π⁰ and direct photon productions at RHIC energies. We find the predictions are opposite to those in the conventional GPM approach.