Near threshold eta meson production in the d+d->alpha+eta reaction

Wronska, A.; Hejny, V.; Wilkin, C.; Dymov, S.; Hanhart, C.; Komarov, V.; Koch, H. R.; Kulikov, A.; Magiera, A.; Mersmann, T.; Mikirtytchiants, S.; Ohm, H.; Prasuhn, D.; Schleichert, R.; Stein, H. J.; Stroeher, H.

Near threshold eta meson production in the d+d->alpha+eta reaction

Authors

Description

The d+d->alpha+eta reaction has been investigated near threshold using the ANKE facility at COSY-Juelich. Both total and differential cross sections have been measured at two excess energies, Q=2.6 MeV and 7.7 MeV, with a subthreshold measurement being undertaken at Q=-2.6 MeV to study the physical background. While consistent with isotropy at the lower energy, the angular distribution reveals a pronounced anisotropy at the higher one, indicating the presence of higher partial waves. Options for the decomposition into partial amplitudes and their consequences for determination of the s-wave eta-alpha scattering length are discussed.
8pp, fig.3 added, normalisation in eq.4.1 corrected