We have observed 23.2±6.0 −0.9 purely-leptonic decays of D + s → μ νμ from a sample of muonic one prong decay events detected in the emulsion target of Fermilab experiment E653. Using the D+ s → φμ νμ yield measured previously in this experiment, we obtain B(D+ s → μ νμ)/B(D + s → φμ νμ) = 0.16 ± 0.06 ± 0.03. In addition, we extract the decay constant fDs = 194 ± 35 ± 20 ± 14 MeV . 1) Aichi University of Education, Kariya 448, JAPAN 2) University of California (Davis), Davis, CA 95616, USA

The diiractive production of 0 (770) mesons in muon-proton interactions is studied in the kinematic region 0.15 GeV 2 < Q 2 < 20 GeV 2 and 20 GeV < < 420 GeV. The data were obtained in the Fermilab xed-target experiment E665 with primary muons of 470 GeV energy. Results are presented on the Q 2 , x and dependence of the cross section, on the shape of the + ? mass spectrum, on the slope of the diiraction peak and on the production and decay angular distributions of the 0 (770). The cross section for diiractive production of 0 by virtual photons on protons depends mainly on Q 2. At xed Q 2 , no signiicant dependence on x or is observed. The extrapolation to Q 2 = 0 yields a photoproduction cross section of (10:30 0:33) b. The slope of the t 0 distribution has a value of (7:00:2) GeV ?2 , with a tendency to decrease as Q 2 increases. The production and decay angular distributions of the 0 depend strongly on Q 2 and are consistent with s-channel helicity conservation. The ratio R = L == T deduced from the decay angular distributions rises strongly with Q 2 , passing the value of 1 at Q 2 2 GeV 2 .

We report results of the first measurements of Λ and ¯ Λ polarization produced in deep inelastic polarized muon scattering on the nucleon. The results are consistent with an expected trend towards positive polarization with increasing x F. The polarizations of Λ and ¯ Λ appear to have opposite signs. A large negative polarization for Λ at low positive x F is observed and is not explained by existing models. A possible interpretation is presented.

The diffractive production of ρ0(770 @#@) mesons in muon-proton interactions is studied in the kinematic region 0.15 GeV2 < Q2 < 20 GeV2 and 20 GeV < ? < 420 GeV. The data were obtained in the Fermilab fixed-target experiment E665 with primary muons of 470 GeV energy. Results are presented on the Q2, x and ? dependence of the cross section, on the shape of the ρ+ρt - mass spectrum, on the slope of the diffraction peak and on the production and decay angular distributions of the ρ0(770). The cross section for diffractive production of ρ0 by virtual photons on protons depends mainly on Q2. At fixed Q2, no significant dependence on x or ? is observed. The extrapolation to Q2 = 0 yields a photoproduction cross section of (10.30 ± 0.33) μb. The slope of the t′ distribution has a value of (7.0 ± 0.2) GeV−2, with a tendency to decrease as Q2 increases. The production and decay angular distributions of the ρ0 depend strongly on Q2 and are consistent with s-channel helicity conservation. The ratio R = σ l /σ t deduced from the decay angular distributions rises strongly with Q2, passing the value of 1 at Q2 ≈ 2 GeV2.

We have observed 23.2 ± 6.0−0.9+1.0 purely-leptonic decays of Ds+ → μ+νμ from a sample of muonic one prong decay events detected in the emulsion target of Fermilab experiment E653. Using the Ds+ → φμ+νμ yield measured previously in this experiment, we obtain B(Ds+ → μ+νμ)B(Ds+ → φμ+νμ) = 0.16 ± 0.06 ± 0.03. In addition, we extract the decay constant fDs = 194 ± 35 ± 20 ± 14 MeV.

The proton and deuteron structure functions F{sub 2}{sup p} and F{sub 2}{sup d} measured in inelastic muon scattering with an average beam energy of 470 GeV. The data were taken at Fermilab experiment 665 during 1991-1992 using liquid hydrogen and deuterium targets. The F{sub 2} measurements are reported in the range 0.0008 < x < 0.6 and 0.2 < Q{sup 2} < 75 GeV{sup 2}. These are the first precise measurements of F{sub 2} in the low x and Q{sub 2} range of the data. The E665 data overlap in x with the HERA data, and there is a smooth connection in Q{sup 2} between the two data sets. At high Q{sup 2} 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 Q{sup 2}. The Q{sup 2} and the W dependence of the data measure the transition in the nature of the photon between a point-probe at high Q{sup 2} and a hadronic object at low Q{sup 2}.

A search for charm hadron decays into two muons plus one or more hadrons has been carried out using a hybrid emulsion spectrometer. This technique is sensitive to modes with missing neutrals, e.g. π0μ+μ− and ϱ±μ+μ−, as well as to constrained modes having visible invariant masses equal to those of charm states. No evidence for any such decays has been found, which allows upper limits at the 90% confidence level as low as 1.8 × 10−4 to be placed on the branching fractions for charm-changing neutral-current and lepton-number violating decay modes.

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<x Bj <0.56 and 0.1<Q2<80 GeV2. The data are consistent with no significant ν orQ2 dependence at fixedx Bj . Asx Bj decreases, the size of the shadowing effect, as well as itsA dependence, are found to approach the corresponding measurements in photoproduction.

The relative branching fraction R(K) = GAMMA(D0 --> K- mu+ nu)/GAMMA(D0 --> mu+ X) has been measured by Fermilab experiment E653, using D0 mesons produced by 600 GeV pi-. The semimuonic decay sample of 232 events was identified by the decay chain D*+ --> D0pi+, D0 --> mu+h-X, where h is a hadron. The Kmunu component was extracted from the joint distribution of these events in the D0 decay variables M(min) and p(Th). We find R(K) = 0.472 +/- 0.051 (stat) +/- 0.040 (sys), and use a world average of the D0 --> Klnu branching fraction to obtain the D0 inclusive semimuonic branching fraction B(D0 --> mu+ X) = (7.67 +/- 1.13)%.

A new method, called graphic scanning, was developed by the Nagoya University Group for emulsion analysis in a hybrid experiment. This method enhances both speed and reliability of emulsion analysis. Details of the application of this technique to the analysis of Fermilab experiment E653 are described.

We present a study of the Cabibbo-allowed semimuonic decay modes of the D(S)+ produced in 600 GeV/c pi--emulsion interactions. From a signal of 18.7 +/- 4.9(-0.7)+0.4 events in the D(S)+ --> phimu+nu channel, the product of production cross section and partial width is measured with respect to that for D+ --> K*0BAR mu+nu to be (sigma(D(S)+)/sigma(D+)). (GAMMA(D(S)+ --> phimu+nu)GAMMA(D+ --> K*0BAR mu+nu)) = 0.56 +/- 0.14 +/- 0.12. The form factor ratios in the decay, obtained by fitting to the decay angles and q2, are A2(0)/A1(0) = 2.1(-0.5)+0.6 +/- 0.2 and V(0) = 2.3(-0.9)+1.1 +/- 0.4, where A1(0) and A2(0) are the axial vector form factors and V(0) is the vector form factor, evaluated at q2 = 0. The first observation of D(S)+ --> (etamu+nu + eta'mu+nu) is also reported, and GAMMA(D(S)+ --> (etamu+nu + eta'mu+nu))/GAMMA(D(S)+ --> phimu+nu) is determined to be 3.9 +/- 1.6.

A search for charm production in the coherent diffractive dissociation reaction pSi-->XSi was carried out for the modes D0-->K-pi+, D0-->K-pi+pi+pi-, and D+-->K-pi+pi+. No charm signals were observed, and the 90% confidence level upper limit for coherent charm pair production was determined to be 26 mub per silicon nucleus. The results are interpreted as an upper limit of 0.2% on the amount of intrinsic charm in the proton.

We report on the characteristics of 9 bbBAR pair events produced by a 600 GeV/c pi- beam and detected in the hybrid emulsion spectrometer of Fermilab experiment E653. The measured lifetimes for samples of 12 neutral and 6 charged beauty hadrons are tau(b0)=0.81+0.34+0.08/-0.22-0.02 ps, and tau(b+/-)=3.84+2.73+0.80/-1.36-0.16 ps.

We report on the production characteristics and total cross section for 9 beauty hadron pairs produced by a 600 GeV/c pi- beam, the first such information in this energy region. The events were detected in the hybrid emulsion spectrometer of Fermilab Experiment E653. The measured pair cross section for all x(F), assuming linear A dependence, is 33 +/- 11 (stat. ) +/- 6 (syst.) nb/nucleon. Fits of the inclusive single-hadron production distribution to the forms dsigma/dx(F) is-proportional-to (1-\x(F)-x0\)n and dsigma/dp(T)2 is-proportional-to exp(-bp(T)2) give n=5.0(-2.1-1.7)+2.7+1.7, x0=0.06(-0.07-0.03)+0.06+0.02, and b=0.13(-0.04-0.02)+0.05+0.02 (GeV/c)-2. The pairs tend strongly to be produced back-to-back.

We report the first observation of the Cabibo disfavored semileptonic decay mode D+ → ρ(770)0 μ+v and measure its decay rate relative to the Cabibbo favored mode D+ → K̄∗ (892)0 μ+v to be Λ(D+ → ρ(770)0 μ+vΛ(D+ → K̄∗ (892)0 μ+v) = 0.0440.031−0.025(stat.) ± 0.014 (syst.). The results are compared to theoretical predictions and to previous experimental upper limits.

The branching ratio for the decay mode D+ --> K*0-mu+-nu-BAR has been measured with two methods. The first uses D0 --> K--mu+-nu for normalization, and yields the result B(D+ --> K*0-mu+-nu)=(3.25+/-0.71+/-0.75)%. From this method we also obtain the direct measurement-GAMMA(D+ --> K*0-mu+-nu)/GAMMA(D0 --> K--mu+-nu)=0.43+/-0.09+/-0.09. The second method uses the mode D+ --> K-pi+-pi+ for normalization and yields B(D+ --> K*0-mu+-nu)=(4.18+/-0.66+/-0.96)%. Combining the results of the two methods yields B(D+ --> K*0-mu+-nu)=(3.57+/-0.96)%.

A measurement of the form factor ratios in the decay D+→K∗(892)0μ+ν is obtained by fitting to the decay angles and q2 of 305 events. The results, evaluated at q2 = 0, are A2(0)/A1(0) = 0.82+0.22−0.23 (stat.)±0.11 (sys.) and V(0)/A1(0) = 2.00+0.34−0.32±0.16, where A1 and A2 are the axial vector form factors and V is the vector form factor. The corresponding ratio of the longitudinal to transverse polarization of the K∗0 is 1.18±0.18±0.08. These results are compared with other experimental results and with theoretical predictions.

A hybrid apparatus consisting of a movable emulsion target and a magnetic spectrometer was used in a fixed target Fermilab Tevatron experiment to study the production of heavy quarks by high-energy hadron beams. High-resolution silicon microstrip detectors were used for precise tracking in the dense particle environment. Details of the experimental apparatus, including the data acquisition system, are described.