Baryon stopping in proton–nucleus collisions Original Research Article

We calculate the inclusive small-x valence quark production cross section in proton–nucleus collisions at high energies. The calculation is performed in the framework of the Color Glass Condensate formalism. We consider both the case when the valence quark originates inside the nucleus and the case when it originates inside the proton. We first calculate the cross section in the quasi-classical approximation resumming the multiple rescatterings with the nucleus. Then we include the effects of double logarithmic reggeon evolution and leading logarithmic gluon evolution in the obtained cross section. The calculated nuclear modification factor for the stopped baryons exhibits Cronin enhancement in the quasi-classical approximation and suppression at high energies/rapidities when quantum evolution corrections are included, providing a new observable which can be used to test Color Glass physics.