Color entanglement for $\gamma$-jet production in polarized pA collisions

Understand

A more reliable treatment of transverse momentum dependent physics and in particular transverse single spin asymmetries is urgently required, e.g.

• for polarized pA physics including novel effects like color entanglement.
• We argue that the measurement of azimuthal angular correlations of photons and jets produced in pA collisions provides a direct access to the novel gluon distribution $G_4$ that enters into many such processes.