We report measurements of the exclusive electroproduction of $K^+\Lambda$ and $K^+\Sigma^0$ final states from a proton target using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The separated structure functions $\sigma_T$, $\sigma_L$, $\sigma_{TT}$, and $\sigma_{LT}$ were extracted from the $\Phi$- and $\epsilon$-dependent differential cross sections taken with electron beam energies of 2.567, 4.056, and 4.247 GeV. This analysis represents the first $\sigma_L/\sigma_T$ separation with the CLAS detector, and the first measurement of the kaon electroproduction structure functions away from parallel kinematics. The data span a broad range of momentum transfers from $0.5\leq Q^2\leq 2.8$ GeV$^2$ and invariant energy from $1.6\leq W\leq 2.4$ GeV, while spanning nearly the full center-of-mass angular range of the kaon. The separated structure functions reveal clear differences between the production dynamics for the $\Lambda$ and $\Sigma^0$ hyperons. These results provide an unprecedented data sample with which to constrain current and future models for the associated production of strangeness, which will allow for a better understanding of the underlying resonant and non-resonant contributions to hyperon production.
Cross sections for incident energy 2.567 GeV for the Q**2 range 0.5 to 0.8 GeV**2 and W range 1.6 to 1.7 GeV.
Cross sections for incident energy 2.567 GeV for the Q**2 range 0.5 to 0.8 GeV**2 and W range 1.70 to 1.75 GeV.
Cross sections for incident energy 2.567 GeV for the Q**2 range 0.5 to 0.8 GeV**2 and W range 1.75 to 1.80 GeV.
Reaction K−p→π0π0Λ was measured at eight incident K− momenta between 514 and 750MeV∕c using the Crystal Ball multiphoton spectrometer. The reaction dynamics are displayed in total cross sections, Dalitz plots, invariant-mass spectra, production angular distributions, and the Λ polarization. The π0π0Λ production is dominated by the π0Σ0(1385) intermediate state; no trace of other light Σ∗ states is observed, and the role of the f0(600) meson appears to be insignificant. A striking similarity is seen between K−p→π0π0Λ and π−p→π0π0n; this can be understood as a consequence of dynamical flavor symmetry.
Measured cross section. Statistical errors only.
Differential cross section for the di-pion system in the c.m. system for incident momenta 514 to 629 MeV.
Differential cross section for the di-pion system in the c.m. system for incident momenta 659 to 750 MeV.
Analyzing powers of pion-proton elastic scattering have been measured at PSI with the Low Energy Pion Spectrometer LEPS as well as a novel polarized scintillator target. Angular distributions between 40 and 120 deg (c.m.) were taken at 45.2, 51.2, 57.2, 68.5, 77.2, and 87.2 MeV incoming pion kinetic energy for pi+ p scattering, and at 67.3 and 87.2 MeV for pi- p scattering. These new measurements constitute a substantial extension of the polarization data base at low energies. Predictions from phase shift analyses are compared with the experimental results, and deviations are observed at low energies.
Analyzing power for PI+ P elastic scattering at incidient kinetic energy 87.2 MeV from the data set 1.
Analyzing power for PI+ P elastic scattering at incidient kinetic energy 68.4 MeV from the data set 1.
Analyzing power for PI+ P elastic scattering at incidient kinetic energy 57.2 MeV from the data set 1.
We present measurements of the differential and total cross sections and the Λ polarization for the reaction K−p→ηΛ from threshold to pK−=770MeV/c, with much better precision than previous measurements. Our cross-section data show a remarkable similarity to the SU(3) flavor-related π−p→ηn cross-section results. The reaction K−p→ηΛ at threshold is dominated by formation of the intermediate Λ(1670)12− state.
Total cross section measurement for K- P --> ETA LAMBDA. Errors shown are statistical only.
Differential cross sections DSIG/DOMEGA for K- P --> ETA LAMBDA. Errors shown are statistical only.
Differential cross sections DSIG/DOMEGA for K- P --> ETA LAMBDA. Errors shown are statistical only.
High quality analyzing powers for the π−p→→π0n reaction have been obtained with a polarized proton target over a broad angular range at incident kinetic energies of 98.1, 138.8, 165.9, and 214.4 MeV. This experiment nearly doubled the existing πN single-charge-exchange database for energies ranging from 10 to 230 MeV, with 36 new analyzing powers. The Neutral Meson Spectrometer was used to detect the outgoing neutral pions. The data are well described by recent phase-shift analyses. When combined with high-precision and accurate cross section data at the same energies, the data can provide a good test of the degree of isospin breaking in the region of the Δ(1232) resonance. They will also be helpful for constraining the evaluation of the pion-nucleon σ term from the scattering amplitudes.
First error is total uncertainty.
First error is total uncertainty.
First error is total uncertainty.
The angles at which the n-p elastic scattering neutron analyzing power A00n0 crosses zero were measured with precision at four TRIUMF energies below 300 MeV. The mean interaction energies are also measured with greater precision than in previous experiments. The results are En=175.26±0.23 MeV, θzx=98.48°±0.28°; En=203.15±0.20 MeV, θzx=91.31°±0.18°; En=217.24±0.19 MeV, θzx=87.64°±0.18°; and En=261.00±0.16 MeV, θzx=80.18°±0.19°. After correction for charge symmetry breaking effects, the energy where the averaged neutron-proton analyzing power crosses zero at θzx=90° is found to be En=206.8±0.6 MeV. © 1996 The American Physical Society.
Polarized beam and target.
Polarized beam and target.
Polarized beam and target.
Analysing powers and differential cross sections for p p → π − π + and p p → K − K + have been measured over the full angular range using a polarised target at LEAR at 20 beam momenta from 360 to 1550 MeV/ c . Discrepancies in the normalisation of earlier d σ/ d Ω data at low momenta are clarified. Above 1000 MeV/ c , A 0N results confirm values close to +1 over most of the angular range for both reactions, in excellent agreement with earlier data of lower statistics. Below 1000 MeV/ c , where the analysing power is measured for the first time, large variations of A 0N with energy and angle are present.
No description provided.
No description provided.
No description provided.
Asymmetries A 0 n have been measured at LEAR for s¯s elastic scattering for 15 beam momenta from 497 to 1550 MeV/ c .
No description provided.
No description provided.
No description provided.
Measurements have been made of the polarisation parameters Σ , T and P for the process γ p → π + n in the photon energy range 520–2250 MeV at c.m. angles between 30° and 120°. These data were obtained in a double polarisation experiment, using the polarised photon beam from the Daresbury electron synchrotron incident on a polarised proton target. The data are compared with predictions from current theoretical analyses.
No description provided.
No description provided.
The polarisation parameters Σ, P and T have been measured for the process γ p→ π 0 p in the photon energy range 1300–2100 MeV and c.m. angles between 30° and 110°, in an experiment with a polarised beam and polarised target. The results are compared with a recent theoretical analysis which fits data from threshold to 16 GeV. The new data are in general agreement with the analysis, but with some significant discrepancies in detail.
No description provided.
No description provided.
No description provided.
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