摘要
The η meson can be bound to atomic nuclei.Experimental search is discussed in the form of final state interaction for the reactions dp → 3 Heη and dd → 4 Heη.For the latter case tensor polarized deuterons were used in order to extract the s-wave strength.For both reactions complex scattering lengths are deduced： a 3 Heη = ± 10.7±0.8 ＋0.1 -0.5 ＋i· 1.5±2.6 ＋1.0-0.9 fm and a 4 Heη = [±（3.1±0.5）＋i·（0±0.5）] fm.In a two-nucleon transfer reaction under quasi-free conditions,p^ 27 Al → ^3 HeX,was investigated.The system X can be the bound 25 Mg η at rest.When a possible decay of an intermediate N （1535） is required,a highly significant bump shows up in the missing mass spectrum.The data give for a bound state a binding energy of 13.3±1.6 MeV and a width of σ=4.4±1.3 MeV.
The η meson can be bound to atomic nuclei.Experimental search is discussed in the form of final state interaction for the reactions dp → 3 Heη and dd → 4 Heη.For the latter case tensor polarized deuterons were used in order to extract the s-wave strength.For both reactions complex scattering lengths are deduced： a 3 Heη = ± 10.7±0.8 ＋0.1 -0.5 ＋i· 1.5±2.6 ＋1.0-0.9 fm and a 4 Heη = [±（3.1±0.5）＋i·（0±0.5）] fm.In a two-nucleon transfer reaction under quasi-free conditions,p^ 27 Al → ^3 HeX,was investigated.The system X can be the bound 25 Mg η at rest.When a possible decay of an intermediate N （1535） is required,a highly significant bump shows up in the missing mass spectrum.The data give for a bound state a binding energy of 13.3±1.6 MeV and a width of σ=4.4±1.3 MeV.
