The structure of the nucleon is studied by means of deep-inelastic neutrino-nucleon scattering at high energies through the weak neutral current. The neutrino-nucleon scattering events were observed in a 340-metric-ton fine-grained calorimeter exposed to a narrow-band (dichromatic) neutrino beam at Fermilab. The data sample after analysis cuts consists of 9200 charged-current and 3000 neutral-current neutrino and antineutrino events. The neutral-current valence and sea nucleon structure functions are extracted from the x distribution reconstructed from the measured angle and energy of the recoil-hadron shower and the incident narrow-band neutrino-beam energy. They are compared to those extracted from charged-current events analyzed as neutral-current events. It is shown that the nucleon structure is independent of the type of neutrino interaction, which confirms an important aspect of the standard model. The data are also used to determine the value of sin2θW=0.238±0.013±0.015±0.010 for a single-parameter fit, where the first error is from statistical sources, the second from experimental systematic errors, and the third from estimated theoretical errors.

The azimuthal dependence of the flow of hadronic energy about the momentum-transfer direction in charged-current deep-inelastic neutrino-nucleon scattering is used to study gluon emission and the transverse momentum 〈kT〉 of partons confined inside the nucleon. A 7-standard-deviation azimuthal asymmetry is observed indicating an average 〈kT〉=0.303±0.041 GeV/c.

We detected 1–10 MeV neutrons at laboratory angles from 80° to 140° in coincidence with 470 GeV muons deep inelastically scattered from H, D, C, Ca, and Pb targets. The neutron energy spectrum for Pb can be fitted with two components with temperature parameters of 0.7 and 5.0 MeV. The average neutron multiplicity for 40<ν<400 GeV is about 5 for Pb, and less than 2 for Ca and C. These data are consistent with a process in which the emitted hadrons do not interact with the rest of the nucleus within distances smaller than the radius of Ca, but do interact within distances on the order of the radius of Pb in the measured kinematic range. For all targets the lack of high nuclear excitation is surprising.

Nuclear shadowing is observed in the per-nucleon cross-sections of positive muons on carbon, calcium and lead as compared to deuterium. The data were taken by Fermilab experiment E665 using inelastically scattered muons of mean incident momentum 470 GeV/c. Cross-section ratios are presented in the kinematic region 0.0001 < XBj <0.56 and 0.1 < Q**2 < 80 GeVc. The data are consistent with no significant nu or Q**2 dependence at fixed XBj. As XBj decreases, the size of the shadowing effect, as well as its A dependence, are found to approach the corresponding measurements in photoproduction.

Nuclear transparencies measured in exclusive incoherent ρ0 meson production from hydrogen, deuterium, carbon, calcium, and lead in muon-nucleus scattering are reported. The data were obtained with the E665 spectrometer using the Fermilab Tevatron muon beam with a mean beam energy of 470 GeV. Increases in the nuclear transparencies are observed as the virtuality of the photon increases, in qualitative agreement with the expectations of color transparency.

Inelastic scattering of 490 GeV μ + from deuterium and xenon nuclei has been studied for x Bj > s .001. The ratio of the xenon/deuterium cross section per nucleon is observed to vary with x Bj , with a depletion in the kinematic range 0.001 < x Bj < 0.025 which exhibits no significant Q 2 dependence. An electromagnetic calorimeter was used to verify the radiative corrections.

Longitudinal and transverse momentum spectra of final state hadrons produced in deep-inelastic muon-deuterium scattering at incident muon energy of 490 GeV have been measured up to a hadronic center of mass energy of 30 GeV. The longitudinal distributions agree well with data from earlier muon-nucleon scattering experiments; these distributions tend to increase in steepness as the center of mass energy increases. Comparisons with e + e − data at comparable center of mass energies indicate slight differences. The transverse momentum distributions show an increase in mean p T 2 with an increase in the center of mass energy.

Results on the production of charged hadrons in muon-deuteron and muon-xenon interactions are presented. The data were taken with the E665 spectrometer, which was exposed to the 490 GeV muon beam of the Tevatron at Fermilab. The use of a streamer chamber as vertex detector provides nearly 4π acceptance for charged particles. The μD data are compared with the μXe data in terms of multiplicity distributions, average multiplicities, forward-backward multiplicity correlations, rapidity and transverse momentum distributions and of two-particle rapidity correlations of charged hadrons. The data cover a range of invariant hadronic massesW from 8 to 30 GeV.

The production ofK0, Λ and\(\bar \Lambda \) particles is studied in the E665 muon-nucleon experiment at Fermilab. The average multiplicities and squared transverse momenta are measured as a function ofxF andW2. Most features of the data can be well described by the Lund model. Within this model, the data on the K0/π± ratios and on the averageK0 multiplicity in the forward region favor a strangeness suppression factors/u in the fragmentation process near 0.20. Clear evidence for QCD effects is seen in the average squared transverse momentum ofK0 and Λ particles.

We present results on the cross-section ratio for inelastic muon scattering on neutrons and protons as a function of Bjorken chi;. The data extend to χ values two orders of magnitude smaller than in previous measurements, down to 2×10 −5 , for Q 2 >0.01 GeV 2 . The ratio is consistent with unity throughout this new range.

We present data on inclusive negative-hadron production from charged-current antineutrino interactions in a 21% Ne-H mixture. Inclusive single-particle distributions are presented and are shown to be insensitive to the momentum transferred to the hadron vertex. Comparisons made to inclusive data from π−p and π−n interactions indicate a close similarity between the hadrons resulting from π-nucleon and ν¯-nucleus interactions. The general features of the ν¯-nucleus data are found to be similar to those seen in ν¯p interactions. This last observation implies that ν¯p and ν¯n interactions are similar and that nuclear effects are small.

A high-statistics study by the Columbia-Chicago-Fermilab-Rochester Collaboration of opposite-sign dimuon events induced by neutrino-nucleon scattering at the Fermilab Tevatron is presented. A sample of 5044 νμ and 1062 ν¯μ induced μ∓μ± events with Pμ1≥9 GeV/c, Pμ2≥5 GeV/c, 30≤Eν≤600 GeV, and 〈Q2〉=22.2 GeV2/c2 is observed. The data support the slow-rescaling model of charm production with a value of mc=1.31±0.24 GeV2/c2. The first measurement of the Q2 dependence of the nucleon strange quark distribution xs(x) is presented. The data yield the Cabibbo-Kobayashi-Maskawa matrix element ‖Vcd‖=0.209±0.012 and the nucleon fractional strangeness content ηs=0.064−0.007+0.008.

This Letter presents measurements of the nucleon structure function F2(x,Q2) based on the deep-inelastic scattering of 215- and 93-GeV muons in the iron multimuon spectrometer at Fermilab. With use of a lowest-order QCD calculation, a value of ΛLO=230±40(stat.)±80(syst.) MeV/c is found.

The rate of neutrino- and antineutrino-induced prompt same-sign dimuon production in steel was measured using a sample of μ−μ− events and 25 μ+μ+ events withPμ>9 GeV/c, produced in 1.5 millionvμ and 0.3 million\(\overline {v_\mu}\) induced charged-current events with energies between 30 GeV and 600 GeV. The data were obtained with the Chicago-Columbia-Fermilab-Rochester (CCFR) neutrino detector in the Fermilab Tevatron Quadrupole Triplet Neutrino Beam during experiments E 744 and E 770. After background subtraction, the prompt rate of same-sign dimuon production is (0.53±0.24)×10−4 pervμ charged-current event and (0.52±0.33)×10−4 per\(\overline {v_\mu}\) charged-current event. The kinematic distributions of the same-sign dimuon events after background subtraction are consistent with those of the non-prompt background due to meson decays in the hadron shower of a charged-current event. Calculations ofc\(\bar c\) gluon bremsstrahlung, based on improved measurements of the charm mass parameter and nucleon structure functions by the CCFR collaboration, yield a prompt rate of (0.09±0.39)×10−4 pervμ charged-current event. In this case,c\(\bar c\) gluon bremsstrahlung is probably not an observable source of prompt same-sign dimuons.

The SciBooNE Collaboration reports inclusive neutral current neutral pion production by a muon neutrino beam on a polystyrene target (C8H8). We obtain (7.7 \pm 0.5(stat.) \pm 0.5 (sys.)) x 10^(-2) as the ratio of the neutral current neutral pion production to total charged current cross section; the mean energy of neutrinos producing detected neutral pions is 1.1 GeV. The result agrees with the Rein-Sehgal model implemented in our neutrino interaction simulation program with nuclear effects. The spectrum shape of the neutral pion momentum and angle agree with the model. We also measure the ratio of the neutral current coherent pion production to total charged current cross section to be (0.7 \pm 0.4) x 10^(-2).

Two different nuclear-medium effects are isolated using a low three-momentum transfer subsample of neutrino-carbon scattering data from the MINERvA neutrino experiment. The observed hadronic energy in charged-current $\nu_\mu$ interactions is combined with muon kinematics to permit separation of the quasielastic and $\Delta$(1232) resonance processes. First, we observe a small cross section at very low energy transfer that matches the expected screening effect of long-range nucleon correlations. Second, additions to the event rate in the kinematic region between the quasielastic and $\Delta$ resonance processes are needed to describe the data. The data in this kinematic region also has an enhanced population of multi-proton final states. Contributions predicted for scattering from a nucleon pair have both properties; the model tested in this analysis is a significant improvement but does not fully describe the data. We present the results as a double-differential cross section to enable further investigation of nuclear models. Improved description of the effects of the nuclear environment are required by current and future neutrino oscillation experiments.

The ratio of the deuteron to proton structure functions is measured at very small Bjorken x (down to 10–6) and for Q2>0.001 GeV2 from scattering of 470 GeV muons on liquid hydrogen and deuterium targets. The ratio F2n/F2p extracted from these measurements is found to be constant, at a value of 0.935±0.008±0.034, for x<0.01. This result suggests the presence of nuclear shadowing effects in the deuteron. The dependence of the ratio on Q2 is also examined; no significant variation is found.

The proton and deuteron structure functions F2p and F2d are measured in inelastic muon scattering with an average beam energy of 470 GeV. The data were taken at Fermilab experiment E665 during 1991 and 1992 using liquid hydrogen and deuterium targets. The F2 measurements are reported in the range 0.0008<x<0.6 and 0.2<Q2<75 GeV2. These are the first precise measurements of F2 in the low x and Q2 range of the data. In the high x range of the data where they overlap in x and Q2 with the measurements from NMC, the two measurements are in agreement. The E665 data also overlap in x with the DESY HERA data, and there is a smooth connection in Q2 between the two data sets. At high Q2 the E665 measurements are consistent with QCD-evolved leading twist structure function models. The data are qualitatively described by structure function models incorporating the hadronic nature of the photon at low Q2. The Q2 and the W dependence of the data measure the transition in the nature of the photon between a pointlike probe at high Q2 and a hadronic object at low Q2.