Invariant-mass distributions for the pp \rightarrow pp \eta reaction at Q = 10 MeV

Proton-proton and proton- $ \eta$ invariant-mass distributions and the total cross-section for the pp $ \rightarrow$ pp $ \eta$ reaction have been determined near the threshold at an excess energy of Q = 10 MeV. The experiment has been conducted using the COSY-11 detector setup and the cooler synchrotron COSY. The determined invariant-mass spectra reveal significant enhancements in the region of low proton-proton relative momenta, similarly as observed previously at higher excess energies of Q = 15.5 MeV and Q = 40 MeV.     

States in 17O excited in the 13C + 9Be \rightarrow 13C + 2 \alpha + n reaction at 90 MeV

The ¹³C + ⁹Be reactions have been measured using a ¹³C beam with an incident energy of 90MeV. The ¹⁷O excitation energy spectra have been reconstructed from the detected ¹³C + $ \alpha$ coincidences. A number of the ¹⁷O states has been observed and their structure has been discussed in relation to the well-known ¹⁶O cluster states.     

Recent results on the {K^-_{\rm stop} + A\rightarrow \Sigma^\pm + \pi^\mp + A^{\prime}} reaction with FINUDA

A study of the $K^-_{\rm stop}A\rightarrow \Sigma^\pm\pi^\mp A^{\prime}$ reaction in some p-shell nuclei, i.e., ^6,7Li, ⁹Be, ¹³C and ¹⁶O, performed by the FINUDA experiment, is reported.     

Comparison of phase space slicing and dipole subtraction methods for \gamma^* \rightarrow Q\bar{Q}

We compare the phase space slicing and dipole subtraction methods in the computation of the inclusive and differential next-to-leading order cross sections for heavy quark production in the simple process . For the phase space slicing method we study the effects of improvement terms that remove restrictions on the slicing parameter . For the dipole method our comparison is a first check on some of its counterterms involving massive quarks, derived recently. In our comparison we address issues such as numerical accuracy and efficiency. Received: 15 October 2001 / Published online: 25 January 2002     

Fusion-fission in the35Cl +12C reaction at Elab=180 MeV

The properties of the two-body channels populated in the³⁵Cl +¹²C reaction, at a bombarding energy of 180 KeV, have been studied by means of a kinematical coincidence technique. Binary reaction products show full energy equilibration and isotropic angular distributions in the center-of-mass frame. The asymmetrical elemental distribution of the fully-damped yields, similar to that observed previously in the³²S +²⁴Mg reaction, suggests the occurence of fusion-fission rather than orbiting.     

Phenomenological model for the \overline{{K}}N \rightarrow K \Xi reaction

A phenomenological model for the $ \overline{{K}}$ N $ \rightarrow$ K $ \Xi$ reaction is suggested. The model includes s and u channel exchanges by $ \Lambda$ , $ \Sigma$ , $ \Sigma$ (1385) , and $ \Lambda$ (1520) and s channel exchanges by above-threshold hyperonic resonances. The explicit expression for the propagator for a particle with spin 7/2 is presented. High-mass and high-spin resonances play a significant role in the process. We deal with the whole set of existing experimental data on the cross-sections and polarizations in the energy range from the threshold to 2.8GeV in the center-of-mass system and reach a good agreement with experiments. Applications of the model to other elementary reactions of $ \Xi$ production and to $ \Xi$ hypernuclear spectroscopy are briefly discussed.