Dihadron azimuthal correlation from the Collins effect in unpolarized hadron collisions

We study the dihadron azimuthal correlation produced nearly back-to-back in unpolarized hadron collisions, arising from the product of two Collins fragmentation functions. Using the latest Collins fragmentation functions extracted from the global analysis of available experimental data, we make predictions for the azimuthal correlation of two-pion production in pp collisions at Relativistic Heavy Ion Collider energies. We find that the correlation is sizable in the midrapidity region for moderate jet transverse momentum.