No Arabic abstract
Kinematic distributions from an inclusive sample of 1.41 x 10^6 charged-current nu_mu interactions on iron, obtained using the MINOS Near Detector exposed to a wide-band beam with peak flux at 3 GeV, are compared to a conventional treatment of neutrino scattering within a Fermi gas nucleus. Results are used to guide the selection of a subsample enriched in quasielastic nu_mu Fe interactions, containing an estimated 123,000 quasielastic events of incident energies 1 < E_nu < 8 GeV, with <E_nu> = 2.79 GeV. Four additional subsamples representing topological and kinematic sideband regions to quasielastic scattering are also selected for the purpose of evaluating backgrounds. Comparisons using subsample distributions in four-momentum transfer Q^2 show the Monte Carlo model to be inadequate at low Q^2. Its shortcomings are remedied via inclusion of a Q^2-dependent suppression function for baryon resonance production, developed from the data. A chi-square fit of the resulting Monte Carlo simulation to the shape of the Q^2 distribution for the quasielastic-enriched sample is carried out with the axial-vector mass M_A of the dipole axial-vector form factor of the neutron as a free parameter. The effective M_A which best describes the data is 1.23 +0.13/-0.09 (fit) +0.12/-0.15 (syst.) GeV.
We present a measurement of the polarization of Antilambda hyperons produced in nu_mu charged current interactions. The full data sample from the NOMAD experiment has been analyzed using the same V0 identification procedure and analysis method reported in a previous paper for the case of Lambda hyperons. The Antilambda polarization has been measured for the first time in a neutrino experiment. The polarization vector is found to be compatible with zero.
Charged-current $ u_{mu}$ interactions on carbon, iron, and lead with a final state hadronic system of one or more protons with zero mesons are used to investigate the influence of the nuclear environment on quasielastic-like interactions. The transfered four-momentum squared to the target nucleus, $Q^2$, is reconstructed based on the kinematics of the leading proton, and differential cross sections versus $Q^2$ and the cross-section ratios of iron, lead and carbon to scintillator are measured for the first time in a single experiment. The measurements show a dependence on atomic number. While the quasielastic-like scattering on carbon is compatible with predictions, the trends exhibited by scattering on iron and lead favor a prediction with intranuclear rescattering of hadrons accounted for by a conventional particle cascade treatment. These measurements help discriminate between different models of both initial state nucleons and final state interactions used in the neutrino oscillation experiments.
Forward single $pi^0$ production by coherent neutral-current interactions, $ u mathcal{A} to u mathcal{A} pi^0$, is investigated using a 2.8$times 10^{20}$ protons-on-target exposure of the MINOS Near Detector. For single-shower topologies, the event distribution in production angle exhibits a clear excess above the estimated background at very forward angles for visible energy in the range~1-8 GeV. Cross sections are obtained for the detector medium comprised of 80% iron and 20% carbon nuclei with $langle mathcal{A} rangle = 48$, the highest-$langle mathcal{A} rangle$ target used to date in the study of this coherent reaction. The total cross section for coherent neutral-current single-$pi^0$ production initiated by the $ u_mu$ flux of the NuMI low-energy beam with mean (mode) $E_{ u}$ of 4.9 GeV (3.0 GeV), is $77.6pm5.0,(text{stat}) ^{+15.0}_{-16.8},(text{syst})times10^{-40},text{cm}^2~text{per nucleus}$. The results are in good agreement with predictions of the Berger-Sehgal model.
We report on the first measurement of flux-integrated single differential cross sections for charged-current (CC) muon neutrino ($ u_mu$) scattering on argon with a muon and a proton in the final state, $^{40}$Ar($ u_mu$,$mu$p)X. The measurement was carried out using the Booster Neutrino Beam at Fermi National Accelerator Laboratory and the MicroBooNE liquid argon time projection chamber detector with an exposure of 4.59 $times$ 10$^{19}$ protons on target. Events are selected to enhance the contribution of CC quasielastic (CCQE) interactions. The data are reported in terms of a total cross section as well as single differential cross sections in final state muon and proton kinematics. We measure the integrated per-nucleus CCQE-like cross section (i.e. for interactions leading to a muon, one proton and no pions above detection threshold) of (4.93 $pm$ 0.76stat $pm$ 1.29sys) $times$ 10$^{-38}$cm$^2$, in good agreement with theoretical calculations. The single differential cross sections are also in overall good agreement with theoretical predictions, except at very forward muon scattering angles that correspond to low momentum-transfer events.
We report the first detailed comparisons of the rates and spectra of neutral-current neutrino interactions at two widely separated locations. A depletion in the rate at the far site would indicate mixing between muon neutirnos and a sterile particle. No anomalous depletion in the reconstructed energy spectrum is observed. Assuming oscillations occur at a single mass-squared splitting, a fit to the neutral- and charged-current energy spectra limits the fraction of muon neutrino oscillating to a sterile neutrino to be below 0.68 at 90% confidence level. A less stringent limit due to a possible contribution to the measured neutral-current event rate at the far site from electron neutrino appearance at the current experimental limit is also presented.