Beam Spin Asymmetry in Semi-Inclusive Electroproduction of Hadron Pairs

A first measurement of the longitudinal beam spin asymmetry A(LU) in the semi inclusive electroproduction of pairs of charged pions is reported. A(LU) is a higher twist observable and offers the cleanest access to the nucleon twist-3 parton distribution function e(x). Data have been collected in the Hall-B at Jefferson Lab by impinging a 5.498-GeV electron beam on a liquid-hydrogen target, and reconstructing the scattered electron and the pion pair with the CLAS detector. One-dimensional projections of the A(LU)(sin phi R) moments are extracted for the kinematic variables of interest in the valence quark region. The understanding of dihadron production is essential for the interpretation of observables in single-hadron production in semi-inclusive DIS, and pioneering measurements of single-spin asymmetries in dihadron production open a new avenue in studies of QCD dynamics.

Automated summary

This study presents the first measurement of the longitudinal beam spin asymmetry A(LU) in the semi-inclusive electroproduction of pairs of charged pions, providing clean access to the nucleon twist-3 parton distribution function e(x). The data were collected at Jefferson Lab in Hall-B by impinging a 5.498-GeV electron beam on a liquid-hydrogen target and reconstructing the scattered electron and the pion pair with the CLAS detector, extracting one-dimensional projections of the A(LU)(sin phi R) moments for the kinematic variables of interest in the valence quark region. Pioneering measurements of single-spin asymmetries in dihadron production play a crucial role in the study of QCD dynamics and are essential for interpreting observables in single-hadron production in semi-inclusive DIS.