Probing superfast quarks in nuclei through dijet production at the LHC

Adam J. Freese, Misak M. Sargsian, Mark I. Strikman

Published 2014-11-24Version 1

We investigate dijet production from proton-nucleus collisions at the Large Hadron Collider (LHC) as a means for observing superfast quarks in nuclei with Bjorken $x>1$. Kinematically, superfast quarks can be identified through directly measurable jet kinematics. Dynamically, their description requires understanding several elusive properties of nuclear QCD, such as nuclear forces at very short distances, as well as medium modification of parton distributions in nuclei. In the present work, we develop a model for nuclear parton distributions at large $x$ in which the nuclear distance at short distance scales is described by two- and three-nucleon short range correlations (SRCs). Nuclear modifications are accounted for by the color screening model, which has previously successfully described the available lepton deep inelastic scattering data. We apply QCD evolution at the leading order to obtain nuclear parton distributions in the kinematic regime of the LHC, and based on the obtained distributions we calculate the cross section for dijet production. We find not only that superfast quarks can be observed at the LHC, but that superfast quarks also provide sensitivity to the practically unexplored three-nucleon SRCs in nuclei.