Modeling Deep Inelastic Cross Sections in the Few GeV Region

Data from atmospheric neutrino experiments [1] have been interpreted as evidence for νμ → ντ oscillations with sin 2 2α > 0.88 and 1.6 × 10 < ∆m < 4 × 10 eV. These neutrino data are in the few GeV region. Therefore, good modeling of νμ and νμ cross sections at low energies is needed. The modeling of νμ and νμ cross sections is even more important for the more precise next generation neutrino oscillations experiments. These include MINOS, MiniBooNE and experiments in the new neutrino facility to be constructed at the JHF high intensity 50 GeV proton synchrontron in Japan. The quark distributions in the proton and neutron are parametrized as Parton Distribution Functions (PDFs) obtained from global fits to various sets of data at very high energies. These fits are done within the theory of Quantum Chromodynamics (QCD) in either leading order (LO) or next to leading order (NLO). The most important data come from deep-inelastic e/μ scattering experiments on hydrogen and deuterium, and νμ and νμ experiments on nuclear targets. In previous publications [2–4] we have compared the predictions of the NLO MRSR2 PDFs to deepinelastic e/μ scattering data [9] on hydrogen and deuterium from SLAC, BCMS and NMC. In order to get agreement with the lower energy SLAC data (down to Q = 1 GeV/c), and at the highest values of x (x = 0.9), we find that modifications to the MRSR2 PDFs must be included.