Cross sections for the $\gamma p \to K^+ \Lambda$ have been measured at backward angles using linearly polarized photons in the range 1.50 to 2.37 GeV. In addition, the beam asymmetry for this reaction has been measured for the first time at backward angles. The $\Lambda$ was detected at forward angles in the LEPS spectrometer via its decay to $p\pi^-$ and the K^+ was inferred using the technique of missing mass. These measurements, corresponding to kaons at far backward angles in the center-of-mass frame, complement similar CLAS data at other angles. Comparison with theoretical models shows that the reactions in these kinematics provide further opportunities to investigate the reaction mechanisms of hadron dynamics.
Differential cross sections as a function of the Mandelstam variable U for photon beam energy 1.5 to 1.8 GeV.
Differential cross sections as a function of the Mandelstam variable U for photon beam energy 1.8 to 2.1 GeV.
Differential cross sections as a function of the Mandelstam variable U for photon beam energy 2.1 to 2.4 GeV.
Beam polarization asymmetries for the p(gamma,K+)Lambda and p(gamma,K+)sigma0 reactions are measured for the first time for Egamma=1.5-2.4 GeV and 0.6<cos(theta_cm(K+))<1.0 by using linearly polarized photons at the Laser-Electron-Photon facility at SPring-8 (LEPS). The observed asymmetries are positive and gradually increase with rising photon energy. The data are not consistent with theoretical predictions based on tree-level effective Lagrangian approaches. Including the new results in the development of the models is, therefore, crucial for understanding the reaction mechanism and to test the presence of baryon resonances which are predicted in quark models but are sofar undiscovered.
Measured beam asymmetries for the reaction GAMMA P --> K+ LAMBDA for beam energy 1.5 to 1.6.
Measured beam asymmetries for the reaction GAMMA P --> K+ LAMBDA for beam energy 1.6 to 1.7.
Measured beam asymmetries for the reaction GAMMA P --> K+ LAMBDA for beam energy 1.7 to 1.8.
We report the first measurement of the vector analyzing power in inclusive transversely polarized elastic electron-proton scattering at Q^2 = 0.1 (GeV/c)^2 and large scattering angles. This quantity should vanish in the single virtual photon exchange, plane wave impulse approximation for this reaction, and can therefore provide information on double photon exchange amplitudes for electromagnetic interactions with hadronic systems. We find a non-zero value of A=-15.4+/-5.4 ppm. No calculations of this observable for nuclei other than spin 0 have been carried out in these kinematics, and the calculation using the spin orbit interaction from a charged point nucleus of spin 0 cannot describe these data.
Polarized beam.
None
Axis error includes +- 3/3 contribution.
Axis error includes +- 3/3 contribution.
Axis error includes +- 3/3 contribution.
The polarization of the recoil neutrons from the reaction γ p→ π + n was measured at a c.m. angle of 105° for incident photon energies between 675 and 1125 MeV. A scattered π + meson and a recoil neutron were detected in coincidence with a magnetic spectrometer and a neutron polarimeter system using liquid hydrogen. Results are compared with recent phenomenological analyses and the other existing data measured by the double polarization measurement technique.
ERRORS ARE STATISTICAL ONLY.
The polarization parameters for the π + +p→K + +∑ + reaction have been measured at 13 laboratory momenta between 1490 and 2069 MeV/ c in the angular range of −0.1⩽ cos θ K ∗ ⩽0.7 with higher statistics than previous experiments. In general, the present results agree well with the results at the Rutherford Appleton Laboratory. It is found, however, that there exist small but systematic differences which can be attributed to certain coefficients in Legendre expansions. The physical significance of these differences is discussed.
No description provided.
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.
The polarization for the\(\bar pp\) elastic scattering was measured as a function of the centre-of-mass angle of scattering between 17° and 90° at the average incident momentum of 0.7 GeV/c by using doublescattering events in a bubble chamber. The average value of the polarization was found to be 0.23 ± 0.05. The angular dependence of the polarization obtained in this experiment was interpreted by the strong absorptive potential model for\(\bar {\mathcal{N}}{\mathcal{N}}\) interactions recently proposed.
SIGN OF POLARIZATION TAKEN AS POSITIVE ACCORDING TO THE DATA OF ALBROW ET AL., NP B37, 349 (1972).
A measurement of the spin correlation parameters A xx (90° cm) and A yy (90° cm) of 47.5 MeV proton-proton scattering has been performed by means of polarized beam and a polarized target.
No description provided.
Analyzing powers for π−p elastic scattering have been measured at TRIUMF using the CHAOS spectrometer and a spin-polarized target. These data were collected at a bombarding energy of Tπ=279MeV and cover an angular range of 53<~θc.m.π<~180°. There is good agreement between these data and the latest partial wave analysis from the VPI/GWU group.
Analysing power measurement.
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