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

## TL;DR

This paper investigates the double spin asymmetry in dihadron production in SIDIS off polarized nucleons, calculating a twist-3 fragmentation function and comparing predictions with experimental data and future collider expectations.

## Contribution

It introduces a new twist-3 dihadron fragmentation function within a spectator model and applies it to analyze azimuthal asymmetries in SIDIS.

## Key findings

- Calculated the unknown twist-3 fragmentation function $ ilde{D}^ ext{sphericalangle}$.
- Estimated azimuthal asymmetries at COMPASS kinematics and compared with data.
- Provided predictions for future EIC measurements.

## Abstract

In this paper we study the double longitudinal spin asymmetry of dihadron production in semi-inclusive deep inelastic scattering (SIDIS). We calculate a unknown twist-3 dihadron fragmentation function $\widetilde{D}^\sphericalangle$ 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 $\cos\phi_R$ azimuthal asymmetry arises from the coupling $e_L H_1^\sphericalangle$ and the coupling $g_1 \widetilde{D}^\sphericalangle$ is studied. We estimate the $\cos\phi_R$ asymmetry at the kinematics of COMPASS and compare with the data. The prediction at the future Electron Ion Collider (EIC) has also been presented.