We present measurements of the differential cross section and Lambda recoil polarization for the gamma p to K+ Lambda reaction made using the CLAS detector at Jefferson Lab. These measurements cover the center-of-mass energy range from 1.62 to 2.84 GeV and a wide range of center-of-mass K+ production angles. Independent analyses were performed using the K+ p pi- and K+ p (missing pi -) final-state topologies/ results from these analyses were found to exhibit good agreement. These differential cross section measurements show excellent agreement with previous CLAS and LEPS results and offer increased precision and a 300 MeV increase in energy coverage. The recoil polarization data agree well with previous results and offer a large increase in precision and a 500 MeV extension in energy range. The increased center-of-mass energy range that these data represent will allow for independent study of non-resonant K+ Lambda photoproduction mechanisms at all production angles.
Differential cross section as a function of COS(THETA(K)) for the centre-of-mass range 1.62-1.63 GeV.
Differential cross section as a function of COS(THETA(K)) for the centre-of-mass range 1.63-1.64 GeV.
Differential cross section as a function of COS(THETA(K)) for the centre-of-mass range 1.64-1.65 GeV.
Differential cross sections for the reaction $\gamma p \to n \pi^+$ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam with energies from 0.725 to 2.875 GeV. Where available, the results obtained here compare well with previously published results for the reaction. Agreement with the SAID and MAID analyses is found below 1 GeV. The present set of cross sections has been incorporated into the SAID database, and exploratory fits have been made up to 2.7 GeV. Resonance couplings have been extracted and compared to previous determinations. With the addition of these cross sections to the world data set, significant changes have occurred in the high-energy behavior of the SAID cross-section predictions and amplitudes.
Differential cross sections for incident photon energies 0.725, 0.775, 0.825and 0.875 GeV.
Differential cross sections for incident photon energies 0.925, 0.975, 1.025and 1.075 GeV.
Differential cross sections for incident photon energies 1.125, 1.175, 1.225and 1.275 GeV.
New results on quasi-free $\eta$ photoproduction on the neutron and proton bound in a deuteron target are presented. The $\gamma n \to \eta n$ quasi-free cross section reveals a bump-like structure which is not seen in the cross section on the proton. This structure may signal the existence of a relatively narrow ($M\sim 1.68$ GeV, $\Gamma \leq 30$ MeV) baryon state.
Quasi free differential cross section for the reaction GAMMA N --> ETA N at COS(THETA(CM)) from -0.9 to -0.5.
Quasi free differential cross section for the reaction GAMMA N --> ETA N at COS(THETA(CM)) from -0.3 to 0.1.
Quasi free differential cross section for the reaction GAMMA N --> ETA N at COS(THETA(CM)) from 0.1 to 0.5.
Revised analysis of $\Sigma$ beam asymmetry for $\eta$ photoproduction on the free proton reveals a resonant structure at $W\sim 1.69$ GeV. Comparison of experimental data with multipole decomposition based on the E429 solution of the SAID partial wave analysis and including narrow states, suggests a narrow ($\Gamma \leq 15$ MeV) resonance. Possible candidates are $P_{11}$, $P_{13}$, or $D_{13}$ resonances. The result is considered in conjunction with the recent evidence for a bump-like structure at $W\sim 1.67 - 1.68$ GeV in quasi-free $\eta$ photoproduction on the neutron.
Measured beam asymmetry for a mean scattering angle of 43 degrees.
Measured beam asymmetry for a mean scattering angle of 65 degrees.
Measured beam asymmetry for a mean scattering angle of 85 degrees.
We present a measurement of the polarization of Antilambda hyperons produced in nu_mu charged current interactions. The full data sample from the NOMAD experiment has been analyzed using the same V0 identification procedure and analysis method reported in a previous paper for the case of Lambda hyperons. The Antilambda polarization has been measured for the first time in a neutrino experiment. The polarization vector is found to be compatible with zero.
Lambdabar polarization in regions of Feynman X (XL).
Lambdabar polarization in regions of the Bjorken scaling variable X.
Using the freon filled bubble chamber SKAT in the (anti)neutrino wide band beam of the Serpukhov accelerator we determine the neutral to charged current cross section ratios for neutrinos and antineutrinos below 30GeV. From these ratios we calculate in leading order a mixing parameter of the standard model of Θw=0.215±0.029.
Axis error includes +- 0.0/0.0 contribution (?////TOTAL SYSTEMATICS).
Axis error includes +- 0.0/0.0 contribution (?////TOTAL SYSTEMATICS).
Axis error includes +- 0.0/0.0 contribution (?////TOTAL SYSTEMATICS).