A measurement of differential cross-sections and nucleon structure functions in charged-current neutrino interactions on iron

A high-statistics measurement of the differential cross-sections for neutrino-iron scattering in the wide-band neutrino beam at the CERN SPS is presented. Nucleon structure functions are extracted and theirQ ² evolution is compared with the predictions of quantum chromodynamics.     

Spin-dependent structure functions for the proton and neutron

We present a phenomenological model for the spin-dependent structure functions g₁(x) of the proton and neutron. The model is an extension of the one proposed by Carlitz and Kaur. We use improved unpolarized structure functions and include effects due to the mass difference between up and down quark and due to the mass difference between spin $\text{1}\text{2}$ and $\text{3}\text{2}$ baryons. Our results for the proton agree with the data.     

νμp and νμn charged-current interactions unfolded from high energy νμ interactions in neon

We have developed a method to separate $\text{ν}$n and $\text{ν}$p interactions from antineutrino-neon interactions by using the final state electric charge. We present the distributions of the scaling variables x and y for $\text{ν}$n and $\text{ν}$p interactions separately , along with the $\text{ν}$n and $\text{ν}$p cross section ratios as a function of x and y. We obtain a total $\text{ν}$n to $\text{ν}$p cross section ratio of 0.45± 0.08. Our results are consistent with the predictions of the simple quark parton model.     

Nucleon structure functions from high energy neutrino interactions

Structure functions obtained from high energy neutrino and antineutrino scattering from an iron target are presented. These were extracted from the combined data of Fermilab experiments E616 and E701; these utilized narrow band beam runs between 1979–1982. The structure functions are used to test the validity of quarkparton model (QPM) predictions and to extract the QCD scale parameter Λ from fits to the Altarelli-Parisi equations.     

A comparison of high statistics measurements of the proton and deuteron structure functions

We present a detailed comparison of high statistics measurements of the structure functionF ₂(x, Q ²) from deep inelastic scattering of charged leptons on hydrogen and deuterium targets. It is found that the CERN results from the EMC and BCDMS Collaborations are both compatible with the lowQ ² electron scattering results from SLAC after an adjustment of the relative normalizations. We discuss the residual discrepancy between EMC and BCDMS which persists after this renormalization and find that the SLAC data are in better agreement with the steeperx dependence of the BCDMS results. A phenomenological parametrization ofF ₂(x, Q ²) is given.     

Tests of scaling of the proton electromagnetic structure functions

Deep-inelastic structure functions W₁ and W₂ have been extracted from electron-proton scattering cross sections that were measured in recent experiments at SLAC. The structure functions display deviations from scaling in the variable ω in the kinetic range 1.5 ? ω ? 3.0 and 2 ? Q² ? 15 GeV².     

Charged-particle multiplicities in charged-current neutrino– and anti-neutrino–nucleus interactions

The CHORUS experiment, designed to search for ν_μ→ν_τ oscillations, consists of a nuclear emulsion target and electronic detectors. In this paper, results on the production of charged particles in a small sample of charged-current neutrino– and anti-neutrino–nucleus interactions at high energy are presented. For each event, the emission angle and the ionization features of the charged particles produced in the interaction are recorded, while the standard kinematic variables are reconstructed using the electronic detectors. The average multiplicities for charged tracks, the pseudo-rapidity distributions, the dispersion in the multiplicity of charged particles and the KNO scaling are studied in different kinematical regions. A study of quasi-elastic topologies performed for the first time in nuclear emulsions is also reported. The results are presented in a form suitable for use in the validation of Monte Carlo generators of neutrino–nucleus interactions.     

Total cross sections of charged-current neutrino and antineutrino interactions on isoscalar nuclei

New measurements of the total crosssections of charged-current interactions of muonneutrinos and antineutrinos on isoscalar nuclei have been performed. Data were recorded in an exposure of the CHARM detector in an 160 GeV narrow-band beam. The antineutrino flux was determined from the measurements of the pion and kaon flux, and independently from the muon flux measured in the shield; the two methods are found to agree. The neutrino flux was determined from the muon flux ratio forv _μ and \(\bar v_\mu \) runs which was normalized to the antineutrino flux. The cross-section slopes thus determined are $$\begin{gathered} \sigma _T^{\bar v} /E = (0.335 \pm 0.004(stat) \hfill \\ \pm 0.010(syst)).10^{ - 38} cm^2 /(GeV \cdot nucleon) \hfill \\ \sigma _T^v /E = (0.686 \pm 0.002(stat) \hfill \\ \pm 0.020(syst)).10^{ - 38} cm^2 /(GeV \cdot nucleon) \hfill \\ \end{gathered} $$ The momentum sum of the quarks in the nucleon and the ratio of sea quark to total quark momentum are derived from the measurements.     

Properties of K0 and Λ inclusive production in charged-current antineutrino-nucleon interactions

In this paper we discuss inclusive spectra of K⁰'s and Λ's produced in charged in charged-current $\text{ν}{}_{\mathrm{\mu }}\text{N}$ interactions in the Fermilab 15 ft bubble chamber filled with a 64% Ne-H₂ mixture. Data presented in terms of the invariant cross section show, when compared with results from experiments with other incident beams, that the behavior of these distributions is approximately the same. The K⁰ and Λ fragmentation functions are presented and the shape of the K⁰ fragmentation function is found to be consistent with the parametrization of Field and Feynman.The average K⁰ and Λ transverse momentum squared as a function of Q², W², x and z is presented. Comparisons for the K⁰'s produced in the current fragmentation region are in qualitative agreement with QCD predictions. The value of the Λ polarization is measured and a positive normal polarization P_N = 0.34±0.18 is found.     

A measurement of the proton structure function F2(x,Q2)

A measurement of the proton structure function F₂(x, Q²) is reported for momentum transfers squared Q² between 4.5 GeV² and 1600 GeV² and for Bjorken x between 1.8 × 10⁻¹⁴ and 0.13 using data collected by the HERA experiment H1 in 1993. It is observed that F₂ increases significantly with decreasing x, confirming our previous measurement made with one tenth of the data available in this analysis. The Q² dependence is approximately logarithmic over the full kinematic range covered. The subsample of deep inelastic events with a large pseudo-rapidity gap in the hadronic energy flow close to the proton remnant is used to measure the “diffractive” contribution to F₂.     

Determination of the parton distributions and structure functions of the proton from neutrino and antineutrino reactions on hydrogen and deuterium

The analytic expressions for the production cross sections of polarized bottom and top quarks ine ^* e ^– annihilation are explicitly derived at the one-loop order of strong interactions. Chirality-violating mass effects will reduce the longitudinal spin polarization for the light quark pairs by an amount of 3%, when one properly considers the massless limit for the final quarks. Numerical estimates of longitudinal spin polarization effects in the processese ^* e ^–b (g) ande ^* e ^–t (g) are presented.supported in part by the BMFT, Germany under contract 06MZ730