Nucleon-resonance decay by the K-0 Sigma(+) channel near threshold

For the combined setup of the Crystal Barrel and TAPS at ELSA in Bonn we have proposed to study the reaction gammap --> K(0)Sigma(+). The reaction is characterised by the final state of 6 photons and a forward emitted proton. Here we report on results of simulations to demonstrate the feasibility of the experiment. From the threshold behaviour of the cross section and angular distributions we aim to search for a 3(rd) S-11 resonance just above the KSigma threshold, which may mix with the two lower lying S-11 resonances and thus provide an explanation for the unusually strong eta branching of the S-11(1535) resonance. The hyperon polarisation can be studied as a sensitive tool to determine the various resonance admixtures

Systematic investigation of the elastic proton-deuteron differential cross section at intermediate energies

To investigate the importance of three-nucleon forces (3NF) systematically over a broad range of intermediate energies, the differential cross sections of elastic proton-deuteron scattering have been measured at proton bombarding energies of 108, 120, 135, 150, 170 and 190 MeV at center-of-mass angles between $30^\circ$ and $170^\circ$. Comparisons with Faddeev calculations show unambiguously the shortcomings of calculations employing only two-body forces and the necessity of including 3NF. They also show the limitations of the latest few-nucleon calculations at backward angles, especially at higher beam energies. Some of these discrepancies could be partially due to relativistic effects. Data at lowest energy are also compared with a recent calculation based on \chipt

Mjerenje s dobrom statistikom emisije dvaju fotona i dileptona pri proton-proton raspršenju na 190 MeV

The first high-statistics measurement of double-photon and dilepton yields in proton-proton scattering below the pion threshold has been performed. The data obtained will allow a detailed study of the proton-proton interaction.Izveli smo prvo mjerenje s dobrom statistikom emisije dvaju fotona i dileptona pri proton-proton raspršenju na energiji ispod praga za produkciju piona. Dobiveni podaci omogućuju dodatno proučavanje svojstava međudjelovanja protona

K^0 pi^0 Sigma^+ and K^*0 Sigma^+ photoproduction off the proton

The exclusive reactions $\gamma p \to K^{*0} \Sigma^+(1189)$ and $\gamma p \to K^{0} \pi^{0}\Sigma^+(1189)$, leading to the p 4$\pi^{0}$ final state, have been measured with a tagged photon beam for incident energies from threshold up to 2.5 GeV. The experiment has been performed at the tagged photon facility of the ELSA accelerator (Bonn). The Crystal Barrel and TAPS detectors were combined to a photon detector system of almost 4$\pi$ geometrical acceptance. Differential and total cross sections are reported. At energies close to the threshold, a flat angular distribution has been observed for the reaction $\gamma p\to K^{0} \pi^{0}\Sigma^+$ suggesting dominant s-channel production. $\Sigma^*(1385)$ and higher lying hyperon states have been observed. An enhancement in the forward direction in the angular distributions of the reaction $\gamma p \to K^{*0}\Sigma^+$ indicates a $t$-channel exchange contribution to the reaction mechanism. The experimental data are in reasonable agreement with recent theoretical predictions.Comment: 11 pages, 13 figures, submitted to EPJ