摘要
The isoscalar monopole excitation of He-4 is studied within a few-body ab initio approach. We consider the transition density to the low-lying and narrow 0(+) resonance, as well as various sum rules and the strength energy distribution itself at different momentum transfers q. Realistic nuclear forces of chiral and phenomenological nature are employed. Various indications for a collective breathing mode are found: (i) the specific shape of the transition density, (ii) the high degree of exhaustion of the non-energy-weighted sum rule at low q, and (iii) the complete dominance of the resonance peak in the excitation spectrum. For the incompressibility K of the alpha particle, two different definitions give two rather small values (22 and 36 MeV).
- 出版日期2015-2-5