ARE THERE BOUND eta-MESONS?

作者：Machner H^*

来源：Acta Physica Polonica B, 2014, 45(3): 705-720.

DOI：10.5506/APhysPolB.45.705

The eta meson can be bound to atomic nuclei. Experimental search is discussed in the form of final state interaction for the reactions dp -> He-3 eta and dd -> He-4 eta. 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)He eta = [+/- (10.7 +/- 0.8(-0.5)(+0.1)) + i (1.5 +/- 2.6+(1.0)(-0.9))] fm 0.9 and a(4)He eta = [+/- (3.1 +/- 0.5) + i (0 +/- 0.5)] fm. For the reaction p(6)Li -> Be-7 eta, more data in the threshold region are necessary to draw any conclusions. In a two-nucleon transfer reaction under quasi-free conditions, p(27)A1 -> (HeX)-He-3 was investigated. The system X can be the bound Mg-25 circle times eta 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 sigma = 4.4 +/- 1.3 MeV.

• 出版日期2014-3