The discovery of hyperon polarization at high energy' gives insight into the dynamics of baryon interactions and also furnishes a method for precise measurements of hyperon moments which, in turn, test composite models of baryon structure. This Letter reports a new me3,4 + ea surement of the X magnetic moment, and the polarization of inclusively produced X+ hyperons. Our moment divers by more than three standard deviations from a recent measurement of comparable precision. The polarization of Z+ hyperons was measured by the asymmetry of the angular distribution in X+ pz . The magnetic moment of the Z+ was determined by precession of the spin in a magnetic field. The experiment was performed in the M2 beam line at Fermilab. The apparatus (Fig. 1) and data taking were described elsewh 67 here. The 400-GeV/c proton beam was directed onto a Be target at angles of +5 or —5 mrad with respect to the Z, + direction. A 5.3-m-long collimator in a 1.24-T downward field defined a 10-rnrad curved channel for the g+ ibeam. The coordinate system at production has +z along the Z+ momentum, +y upwards, and x =y&z. The decay chain Z+ pz, z 2y was detected by a wire-chamber spectrometer and a lead-glass array (PbG). The trigger required a charged particle in the spectrometer (S~ C4 PC), and at least one y in the lead glass (T PbG). Two radiation lengths of lead were placed before C5 above and below the M3 aperture to shower wide-angle y's for position determination in C5. Event categories were based on the amount of information present. Gamma categories were events with only one y in PbG and the other undetected, one y in PbG and position data on the other in C5, or both y's in PbG. Charged-track data fell in two categories: 60% Ml 40O Gev PROTONS S2 C1 C2 C3 C4 M3 Cs@ C7 LEAD GLASS

AbstractThe 1H and 13C NMR spectra of the deoxyhemigossypol derivatives 4‐isopropyl‐2,3‐dimethoxy‐6‐methylnaphthalene, 4‐isopropyl‐2,3‐dimethoxy‐6‐methyl‐1‐naphthaldehyde and 2,3‐dihydroxy‐4‐isopropyl‐6‐methyl‐1‐naphthaldehyde were assigned using one‐ and two‐dimensional NMR techniques, including DEPT, 1H NOE and 1H13C HETCORR spectroscopy.

The H-1 and C-13 NMR spectra of the deoxyhemigossypol derivatives 4-isopropyl-2,3-dimethoxy-6-methylnaphthalene, 4-isopropyl-2,3-dimethoxy-6-methyl-1-naphthaldehyde and 2,3-dihydroxy-4-isopropyl-6-methyl-1-naphthaldehyde were assigned using one- and two-dimensional NMR techniques, including DEFT, H-1 NOE and H-1-C-13 HETCORR spectroscopy.

The analysis of 37 286 $\ensuremath{\Lambda}$ $\ensuremath{\beta}$ decays yields the axial-vector-to-vector coupling ratio $\frac{{g}_{a}(0)}{{g}_{v}(0)}=+0.731\ifmmode\pm\else\textpm\fi{}0.016$, ${\ensuremath{\alpha}}_{e\ensuremath{\nu}}=\ensuremath{-}0.27\ifmmode\pm\else\textpm\fi{}0.013$ with the weak-magnetism coupling $w=\frac{{g}_{w}(0)}{{g}_{v}(0)}=0.15\ifmmode\pm\else\textpm\fi{}0.30$. The error is statistical only and there is no evidence for any significant systematic error. A new method is presented for resolving problems arising from the quadratic ambiguity in the analysis of this decay process. The ${q}^{2}$ dependence of the form factors has been included. Both the internal and external radiative corrections have been made. If $w$ is constrained to be 0.97, the conserved-vector-current value, $\frac{{g}_{a}(0)}{{g}_{v}(0)}=+0.719\ifmmode\pm\else\textpm\fi{}0.016\ifmmode\pm\else\textpm\fi{}0.012$, where the uncertainties are statistical and systematic, respectively. The corresponding value of the electron-neutrino correlation is ${\ensuremath{\alpha}}_{e\ensuremath{\nu}}=\ensuremath{-}0.017\ifmmode\pm\else\textpm\fi{}0.013\ifmmode\pm\else\textpm\fi{}0.010$.

We have obtained a sample of 1743 reconstructed ${\ensuremath{\Omega}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}\ensuremath{\Lambda}${K}^{\mathrm{\ensuremath{-}}}$ events produced by protons on a Be target at production angles of 5.0 and 7.5 mrad. The ${\ensuremath{\Omega}}^{\mathrm{\ensuremath{-}}}$ lifetime, based on a subset of 1096 events, was measured to be \ensuremath{\tau}(${\mathrm{\ensuremath{\Omega}}}^{\mathrm{\ensuremath{-}}}$)=(0.811\ifmmode\pm\else\textpm\fi{}0.037)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}10}$ sec, where the uncertainty is statistical and the systematic uncertainty is estimated to be small. The helicity of the daughter \ensuremath{\Lambda} yielded the product of asymmtery parameters ${\ensuremath{\alpha}}_{\ensuremath{\Lambda}}$${\ensuremath{\alpha}}_{\ensuremath{\Omega}}$=-0.022\ifmmode\pm\else\textpm\fi{}0.051 which, in turn, yields ${\ensuremath{\alpha}}_{\ensuremath{\Omega}}$=-0.034\ifmmode\pm\else\textpm\fi{}0.079. The average daughter-\ensuremath{\Lambda} polarization in the decay region was measured to be ${P}_{\ensuremath{\Lambda}}$=0.12\ifmmode\pm\else\textpm\fi{}0.08 approximately perpendicular to the charged-hyperon beam line. The ${\ensuremath{\Omega}}^{\mathrm{\ensuremath{-}}}$ polarization in the same region, i.e., after the precession magnet, depends on the sign of ${\ensuremath{\gamma}}_{\ensuremath{\Omega}}$, which is unknown at present. The two possibilities are ${P}_{\ensuremath{\Omega}}$=${P}_{\ensuremath{\Lambda}}$ if ${\ensuremath{\gamma}}_{\ensuremath{\Omega}}$\ensuremath{\approxeq}+1 and ${P}_{\ensuremath{\Omega}}$=-(5/3${P}_{\ensuremath{\Lambda}}$ if ${\ensuremath{\gamma}}_{\ensuremath{\Omega}}$\ensuremath{\approxeq}-1. The magnitude of the polarization vector is only 1.5 standard deviations different from zero, and this prevented a meaningful measurement of the ${\ensuremath{\Omega}}^{\mathrm{\ensuremath{-}}}$ magnetic moment. If the broken-SU(6) prediction for the moment, \ensuremath{\mu}(${\ensuremath{\Omega}}^{\mathrm{\ensuremath{-}}}$)=-1.83${\ensuremath{\mu}}_{N}$, is assumed to be true, then the precession of the ${\ensuremath{\Omega}}^{\mathrm{\ensuremath{-}}}$ in the magnetic field is small and the values of ${P}_{\ensuremath{\Omega}}$ above are also true at the production target. If this polarization is different from zero and correct in sign, then it cannot be simultaneously reconciled with theoretical predictions for the sign of ${\ensuremath{\gamma}}_{\ensuremath{\Omega}}$ and for the sign of the production polarization. On the other hand, if the polarization is zero no inconsistency exists.

We present results on exclusive single-charged pion and kaon production in neutrino and antineutrino interactions on protons in the energy range from 5 to 120 GeV. The data were obtained from exposures of BEBC to wide band beams at the CERN SPS. For invariant masses of the (pπ) system below 2 GeV, the pions originate predominantly from decays of baryon resonances excited by the weak charged current. Similarly, we observe the production of Λ(1520) decaying into p and K−. For invariant masses above 2 GeV pion production becomes peripheral by interaction of the weak current with a virtual π0. We establish a contribution of longitudinally polarised intermediate vector bosons to this process.

The ratios Rvp and Rvp of the neutral current to charged current cross sections for neutrino and antineutrino interactions on protons have been measured in BEBC. The beam was the CERN SPS 400 GeV wideband beam. The bubble chamber, equipped with the standard External Muon Identifier, was surrounded with an additional plane of wire chambers (Internal Picket Fence), which was added to improve neutral current event identification. For a total transverse momentum of the charged hadrons above 0.45 GeV/c and a charged multiplicity of at least 3, it was found that Rvp = 0.384 ± 0.015 and Rvp = 0.338 ± 0.014 ± 0.016, corresponding to a value of sin2θw(MwMS of 0.225 ± 0.030. Combining the results from hydrogen and an isoscalar target, the differences of the neutral current chiral coupling constants were found to be u2l−d2L = −0.080 ± 0.043 ± 0.012 and u2R−d2R = 0.021±0.055±0.028.

The polarization of ${\ensuremath{\Xi}}^{\mathrm{\ensuremath{-}}}$ hyperons produced by 400-GeV protons in the reaction p+Be\ensuremath{\rightarrow}${\ensuremath{\Xi}}^{\mathrm{\ensuremath{-}}}$+X has been measured as a function of momentum at two production angles. The average polarization for the full sample (192 110 events) was -0.108\ifmmode\pm\else\textpm\fi{}0.007. Comparisons are made with polarization measurements for other hyperons produced under similar conditions. From the same data, ${\ensuremath{\alpha}}_{\ensuremath{\Lambda}}$${\ensuremath{\alpha}}_{\ensuremath{\Xi}}$ was measured to be -0.303\ifmmode\pm\else\textpm\fi{}0.004\ifmmode\pm\else\textpm\fi{}0.004, where ${\ensuremath{\alpha}}_{\ensuremath{\Lambda}}$ is the asymmetry parameter in the decay \ensuremath{\Lambda}\ensuremath{\rightarrow}p${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$, ${\ensuremath{\alpha}}_{\ensuremath{\Xi}}$ is the asymmetry parameter in the decay ${\ensuremath{\Xi}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}\ensuremath{\Lambda}${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$, and the uncertainties are statistical and systematic, respectively. This yields ${\ensuremath{\alpha}}_{\ensuremath{\Xi}}$=-0.472\ifmmode\pm\else\textpm\fi{}0.006\ifmmode\pm\else\textpm\fi{}0.011, where the systematic uncertainty is dominated by the uncertainty in ${\ensuremath{\alpha}}_{\ensuremath{\Lambda}}$. An updated test of the \ensuremath{\Delta}I=1/2 rule in \ensuremath{\Xi} decay is presented.

Inclusive production cross sections have been measured for the processes p-italic+A-italic..--> gamma../sup 0/+X (A-italic = Be, Cu, Pb) and for p-italic+Be..-->..Xi-bar/sup 0/+X. Data were taken at angles of 0, 2, 3.5, 7.3, and 9.8 mrad between the incident 400-GeV proton beam and the outgoing hyperon beam. Production cross sections for ..lambda.. and Lambda-bar production were measured at the same time. The A-italic dependence of the ..gamma../sup 0/ cross sections is discussed, along with interpretations in terms of various models.

Inclusive ϱ0 production has been studied in antineutrino-proton charged current interactions, using a sample of 3340 events obtained in BEBC filled with hydrogen and exposed to the CERN wideband antineutrino beam. An average multiplicity of 0.11 ± 0.02ϱ0 per event at a mean hadronic mass W of 4.2 GeV is observed. The ϱ0 production characteristics are determined as functions of pT, xF, and z. The ratio ϱ0/“π0” is found to be low at small z values consistent with centrally produced pions coming mainly from resonances. At large z values this ratio approaches 0.45 ± 0.15 which is compatible with a vector/pseudoscalar meson direct production ratio of one. The results are compared with those obtained from neutrino-proton interactions in the same experimental set-up.

Inclusive production cross sections have been measured for the processes p+A\ensuremath{\rightarrow}${\ensuremath{\Xi}}^{0}$+X (A=Be, Cu, Pb) and for p+Be\ensuremath{\rightarrow}\ensuremath{\Xi}${\ifmmode\bar\else\textasciimacron\fi{}}^{0}$+X. Data were taken at angles of 0, 2, 3.5, 7.3, and 9.8 mrad between the incident 400-GeV proton beam and the outgoing hyperon beam. Production cross sections for \ensuremath{\Lambda} and \ensuremath{\Lambda}\ifmmode\bar\else\textasciimacron\fi{} production were measured at the same time. The A dependence of the ${\ensuremath{\Xi}}^{0}$ cross sections is discussed, along with interpretations in terms of various models.

The prompt electron neutrino and muon neutrino fluxes from proton copper interactions at 400 GeV/c proton momentum have been measured. The asymmetry between the prompt electron (anti) neutrino and the prompt muon (anti) neutrino event rates above 20 GeV is A e μ = (N e − N μ (N c + N μ ) = 0.07 ± 0.08 corresponding to an Ne/Nμ ratio of 1.14−0.16−0.19. The cross section weighted charge asymmetry for electrons and muons combined is A ν ν = 0.15 ± 0.08 . The number of D decays into ν e and ν μ is (4.1 ± 0.9) × 10 −4 per incident proton. No evidence for ντ interactions was found.

A xenon filled multiwire proportional chamber was used to detect synchrotron radiation from high energy electrons traversing the field of a standard spectrometer magnet. Signals from the chamber were used to achieve an electron trigger with a pion rejection of ∼ 17 and an average electron detection efficiency of 81%. Off-line analysis of the chamber signals increased the pion rejection to 59 with an electron efficiency of 77%.

Lambda hyperons fromv p and <img src="/fulltext-image.asp?format=htmlnonpaginated&src=U74G4L1888070675_html\10052_2005_Article_BF01550245_TeX2GIFIE2.gif" border="0" alt=" $$\bar v$$ " />p charged current interactions have been analysed for polarization. A significant polarization is observed for ? particles in the quasi-elastic region for both types of interactions. Part of this polarization is due to the decay of highly polarized S(1385) resonances. The results are compared with simple predictions of the quark parton model.

Neutral kaon to negative pion production ratios fromvp and\(\bar vp\) charged current interactions in BEBC are presented and compared with LUND fragmentation model predictions. Good agreement is obtained with a strangeness suppression factor λ=0.203±0.014(stat)±0.010(sys). No evidence is seen for an energy dependence of λ in our kinematic region.