Probing gluon nuclear PDF with direct photon production in association   with a heavy quark
  We investigate a possible use of direct photon production in association with a heavy quark in $pA$ collisions at the large hadron collider to constrain the nuclear gluon parton distribution function. This process is sensitive to both, the nuclear heavy quark and gluon parton distribution functions and is a very promising candidate to help determine the gluon nuclear PDF which is still largely untested. 
K. Kovarik, T. Stavreva
hep-ph