  We measured the nuclear dependence of the di-pion azimuthal correlation
function in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance
Spectrometer (CLAS) and a 5 GeV electron beam. As the nuclear-target size
increases, transitioning from deuterium to carbon, iron, and lead, the
correlation function broadens monotonically. Its shape exhibits a significant
dependence on kinematics, including the transverse momentum of the pions and
the difference in their rapidity. None of the various Monte-Carlo event
generators we evaluated could fully replicate the observed correlation
functions and nuclear effects throughout the entire phase space. As the first
study of its kind in DIS experiments, this research provides an important
baseline for enhancing our understanding of the interplay between the nuclear
medium and the hadronization process in these reactions.
