  The observation of beam spin asymmetries in two-pion production in
semi-inclusive deep inelastic scattering off an unpolarized proton target is
reported. The data presented here were taken in the fall of 2018 with the
CLAS12 spectrometer using a 10.6 GeV longitudinally spin-polarized electron
beam delivered by CEBAF at JLab. The measured asymmetries provide the first
opportunity to extract the parton distribution function $e(x)$, which provides
information about the interaction between gluons and quarks, in a collinear
framework that offers cleaner access than previous measurements. The
asymmetries also constitute the first ever signal sensitive to the
helicity-dependent two-pion fragmentation function $G_1^\perp$. A clear sign
change is observed around the $\rho$ mass that appears in model calculations
and is indicative of the dependence of the produced pions on the helicity of
the fragmenting quark.
