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     

Production of charmed hadrons in neutrino proton and antineutrino proton charged current interactions

Usind data from avp and \(\bar v\) p experiment with BEBC at CERN, the rates for inclusive production ofD ^*+,Λ _c ⁺ andD ⁰ invp scattering and ofD ^*? in \(\bar v\) p scattering are measured. Some examples of the exclusive production ofD ^*+,Λ _c ⁺ and∑ _c ⁺⁺ are given. The cross section for the reactionvp→μ ^? _c ⁺⁺ is estimated.     

Investigation of like-sign dimuon production in neutrino and antineutrino reactions

290 events of the type νFe→μ^?μ^?X and 53 events from the reaction $\text{ν}\text{Fe→μ}{}^{\mathrm{+}}\text{μ}{}^{\mathrm{+}}\text{X with}\text{E}{}_{\mathrm{\nu }}\text{>30}\text{GeV}$ and muon momenta p_μ>6.5GeV/c have been observed in the CDHS detector. After subtracting the background from charged-current processes with one π or K meson of the hadronic shower decaying into $\text{μ}{}^{\mathrm{?}}\text{ν}\text{(or μ}{}^{\mathrm{+}}\text{μ)}$, we obtain for neutrinos a rate of prompt like- sign dimuon production of (3.4±1.8)×10^?5 relative to the rate of charged-current events with the same cuts, or (4.1 ± 2.2)% relative to the prompt μ^?μ⁺ rate, and for antineutrinos the corresponding relative rates (4.3±2.3)×10^?5 and (4.2 ± 2.3)%. A possible explanation for the events is charm pair production at a level of 10^?3 relative to all charged-current reactions.     

Fragmentation in neutrino and antineutrino charged current interactions on proton and neutron

Some experimental properties of the charged hadronic fragments are compared for νp, νn, \(\bar vp\) and \(\bar vn\) interactions: multiplicities of forward and backward going particles,x _F distributions for pions, fragmentation functions and theirQ ² andW ² dependence. The results are compared with the predictions of the Lund fragmentation model.     

Measurement of neutrino and antineutrino structure functions in hydrogen and iron

The CDHS neutrino detector has been used to measure events originating in a tank of liquid hydrogen and in the iron of the detector. Total cross-sections, differential cross-sections, and structure functions are given for hydrogen and compared with those in iron. The measurements are in agreement with the expectations of the quark parton model. No significant differences indicative of nuclear binding effects in corresponding structure functions of protons and iron are observed. This may be of special interest in the case of the sea structure functions, since large differences are expected in some models.     

Test of scaling alone from y-distributions in high-energy neutrino (antineutrino) reactions

Upper and lower bounds to y-density distributions in high energy neutrino (antineutrino) reactions are derived from the assumption of scaling of the weak structure functions alone. A discussion on the bearing of these bounds to present neutrino experiments is also given.     

Momentum distributions and ionization potentials for the valence orbitals of hydrogen fluoride and hydrogen chloride

The binding-energy spectra and momentum distributions for the valence orbitais of HF and HCI have been obtained at 1200 and 400 eV using (e, 2e) spectroscopy with symmetric kinematics For HC1, the strength of the innermost valence-orbital (4cr) is found to be significantly split among several ion~states in the range 20ú41 eV The corresponding orbital (2G) in HF is, however, not significantly split among ion states The measured momentum-distributions are compared with the results of several calculations of at least double-zeta quality, as well as with a one-particle Greenæs function calculation of the generalized overlap amplitude (GOA) Agreement in shape is quite good for the innermost orbitais, but for the ii and outer a orbitais of HF, the momentum distributions calculated directly from the molecular orbitais are significantly more extended in momen- tum space than are the measured distributions The Greenæs function calculations give momentum distributions in reasonable agreement with the data, and pole-strengths for transitions which are in qualitative agreement with the observed cross-sections     

Experimental test of the PCAC-hypothesis in charged current neutrino and antineutrino interactions on protons

Data obtained with the bubble chamber BEBC at CERN are used for the first significant test of Adler's prediction for the neutrino and antineutrino-proton scattering cross sections at vanishing four-momentum transfer squaredQ ². An Extended Vector Meson Dominance Model (EVDM) is applied to extrapolate Adler's prediction to experimentally accessible values ofQ ². The data show good agreement with Adler's prediction forQ ²→0 thus confirming the PCAC hypothesis in the kinematical region of high leptonic energy transfer ν>2 GeV. The good agreement of the data with the theoretical predictions also at higherQ ², where the EVDM terms are dominant, also supports this model. However, an EVDM calculation without PCAC is clearly ruled out by the data.     

Electron momentum distributions and binding energies for the valence orbitals of hydrogen bromide and hydrogen iodide

Electron binding energy spectra and momentum distributions have been obtained for the valence orbitals of HBr and HI using noncoplanar symmetric electron coincidence spectroscopy at 1200 eV. The weakly bonding inner valence ns orbitals, which have not been observed previously, have their spectroscopic (pole) strength severely split among a number of ion states. For HBr the strength of the “main” inner valence (ns) transition is 0.42±0.03 whereas for HI it is 0.37±0.04, in close agreement with the value observed for the valence s orbitals of the corresponding isoelectronic inert-gas atoms. The spectroscopic strength for the two outermost orbitals is found to be close to unity, in agreement with many-body Green's function calculations. The measured momentum distributions are compared with several spherically averaged MO momentum distributions, as well as (for HBr) with a Green's function calculation of the generalized overlap amplitude (GOA). The GOA momentum distributions are in excellent agreement with the HBr data, both in shape and relative magnitude. Not all of the MO momentum distributions are in reasonable agreement with the data. Comparison is also made with the calculated momentum distributions for Kr, Br, Xe and I.     

Determination of the strange quark content of the nucleon from a next-to-leading-order QCD analysis of neutrino charm production

We present the first next-to-leading-order QCD analysis of neutrino charm production, using a sample of 6090 ^– and -induced opposite-sign dimuon events observed in the CCFR detector at the Fermilab Tevatron. We find that the nucleon strange quark content is suppressed with respect to the non-strange sea quarks by a factor =0.477 _–0.053 ^+0.063 , where the error includes statistical, systematic and QCD scale uncertainties. In contrast to previous leading order analyses, we find that the strange seax-dependence is similar to that of the non-strange sea, and that the measured charm quark mass,m _c =1.70±0.19 GeV/c², is larger and consistent with that determined in other processes. Further analysis finds that the difference inx-distributions betweenxs(x) and is small. A measurement of the Cabibbo-Kobayashi-Maskawa matrix element |V _cd |=0.232 _–0.020 ^+0.018 is also presented.     

Coherent pion production in neutrino and antineutrino interactions on nuclei of heavy freon molecules

Studying the coherent diffractive production of pions in neutrino and antineutrino scattering off the nuclei of freon molecules we have observed for the first time in one experiment all three states of the isospin triplet of the axial part of the weak charged and neutral currents. For the corresponding cross sections we derive $$\begin{array}{*{20}c} {\sigma _{coh}^v (\pi ^ + ) = (106 \pm 16) \cdot 10^{ - 40} {{cm^2 } \mathord{\left/ {\vphantom {{cm^2 } {\left\langle {nucl.} \right\rangle }}} \right. \kern-\nulldelimiterspace} {\left\langle {nucl.} \right\rangle }}} \\ {\sigma _{coh}^{\bar v} (\pi ^ - ) = (113 \pm 35) \cdot 10^{ - 40} {{cm^2 } \mathord{\left/ {\vphantom {{cm^2 } {\left\langle {nucl.} \right\rangle }}} \right. \kern-\nulldelimiterspace} {\left\langle {nucl.} \right\rangle }}and} \\ {\sigma _{coh}^v (\pi ^0 ) = (52 \pm 19) \cdot 10^{ - 40} {{cm^2 } \mathord{\left/ {\vphantom {{cm^2 } {\left\langle {nucl.} \right\rangle }}} \right. \kern-\nulldelimiterspace} {\left\langle {nucl.} \right\rangle }}} \\ \end{array} $$ . Comparing our data with theoretical predictions based on the standard model of weak interactions we find reasonable agreement. Independently from any model of coherent pion production we determine the isovector axial vector coupling constant to be |β|=0.99±0.20.     

Neutrino and antineutrino proton scattering data and the ratio of down to up quarks in the proton

New data on the x-dependence of the ratio of down to up quarks in the proton are presented from neutrino and antineutrino experiments using the Fermilab 15-foot bubble chamber filled with hydrogen. The new data are in good agreement with existing data from electron scattering experiments performed at SLAC but are not accurate enough at large x to discriminate between the QCD prediction and a (1 ? x) behavior as x → 1.     

Measurement of the inclusive charged-current cross section for neutrino and antineutrino scattering on isoscalar nucleons

This paper reports on measurements of the total cross section for the inclusive reaction v_μ+N , as a function of incident energy. Neutrinos and antineutrinos with energy in the range 30–300 GeV were produced in the 1982 Fermilab narrow-band neutrino beamline. A total of 35 000 neutrino and 7000 antineutrino interactions were recorded in the CCFR detector located in LabE. The incident neutrino flux was determined by methods similar to those used in previous experiments. The rate of increase with energy of the total cross section (σ/E _v) in the range 30 to 75 GeV was determined to be 0.659±0.005(stat)±0.039(syst)×10^?38 cm²/GeV and 0.307±0.008(stat)±0.020(syst)×10^?38 cm²/GeV for incident neutrinos and antineutrinos, respectively. The 5.9% systematic errors are due primarily to uncertainties in the flux intensity measurement. The energy dependence of the cross section in the regionE _ν=100–300 GeV was found to be linear, as determined by relative normalization techniques. A weighted average of our previous and present measurement for the total ν-N cross section yields: $$\begin{gathered} \sigma (vN) = 0.666 \pm 0.020(statistical \hfill \\ + systematic)E_v 10^{ - 38} cm^2 ; \hfill \\ \sigma (\bar vN) = 0.324 \pm 0.014(statistical \hfill \\ + systematic)E_v 10^{ - 38} cm^2 ; \hfill \\ \end{gathered} $$ .