  The prospects of measuring a single-differential dijet cross section during
the proposed short proton-oxygen data taking at LHC Run 3 are studied using
next-to-leading-order perturbative QCD predictions. With reasonable
experimental cuts and luminosity estimates, such a measurement is found to be
feasible, and a few inverse nanobarns of integrated luminosity is estimated to
be enough to yield new constraints on parton distribution functions (PDFs) of
light nuclei. In the absence of a dedicated proton-proton reference, a
mixed-energy nuclear modification ratio is proposed for cancelling free-proton
PDF uncertainties to obtain a direct access to the nuclear modifications of the
parton distributions in oxygen.
