Double spin asymmetry in dihadron production in SIDIS off a longitudinally polarized nucleon target

In this paper, we study the double longitudinal spin asymmetry of dihadron production in semi-inclusive deep inelastic scattering. We calculate an unknown twist-three dihadron fragmentation function D^{∼ ∢} within a spectator model which has been used successfully in describing the dihadron production in both the unpolarized and the single polarized processes. The collinear picture in which the transverse momentum of the final state hadron pair is integrated out has been considered. The cos ϕ_R azimuthal asymmetry arising from the coupling e_LH₁^∢ and the coupling g₁D^{∼ ∢} is studied. In general, e_L(x ) and its respective contribution vanish model independently and g₁D^{∼ ∢} dominates in this asymmetry. Moreover, we have adopted the same choice as before for the quark mass m fixed to zero GeV, which eliminates the Re [F^{s *}F^p] contribution to the D^∼∢. Using the model results obtained at the low hadronic scale and neglecting the QCD evolution effects, we estimate the cos ϕ_R asymmetry and compare with the COMPASS preliminary data. An estimate for the future electron ion collider is also presented.