arXiv:nucl-ex/9703002·v1·Nuclear Experiment
Eta-Helium Quasi-Bound States
N. Willis🇫🇷 · Y. Le Bornec🇫🇷 · A. Zghiche🇫🇷 · C. Wilkin🇬🇧 · R. Wurzinger🇫🇷 · O. Bing🇫🇷 · M. Boivin🇨🇦 · P. Courtat🇫🇷 · R. Gacougnolle🇨🇦 · F. Hibou🇫🇷 · J. M. Martin🇫🇷 · F. Plouin🇨🇦 · B. Tatischeff🇫🇷 · J. Yonnet🇨🇦
Abstract
The cross section and tensor analysing power t_20 of the d\vec{d}->eta 4He reaction have been measured at six c.m. momenta, 10 < p(eta) < 90 MeV/c. The threshold value of t_20 is consistent with 1/\sqrt{2}, which follows from parity conservation and Bose symmetry. The much slower momentum variation observed for the reaction amplitude, as compared to that for the analogous pd->eta 3He case, suggests strongly the existence of a quasi-bound state in the eta-4He system and optical model fits indicate that this probably also the case for eta-3He.
Comments: LaTeX, uses elsart.sty, 10 pages, 3 Postscript figures, Submitted to Physics Letters B