Is the first excited state of the $\alpha$-particle a breathing mode?

Abstract

The isoscalar monopole excitation of 4He 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 values between 20 and 30 MeV are found.

5 pages, 2 figures

References in corpus (3)

• Local three-nucleon interaction from chiral effective field theory
• The Lorentz Integral Transform (LIT) method and its applications to perturbation induced reactions
• Photonuclear sum rules and the tetrahedral configuration of ${}^4$He

Cited by in corpus (5)

• Energy Resolution with the Lorentz integral transform
• Electromagnetic reactions on light nuclei
• Calculation of the astrophysical S-factor S_12 with the Lorentz integral transform
• Derivation of transition density from the observed 4He(e,e')4He(0^+_2) form factor raising the alpha-particle monopole puzzle
• Description of the proton-decaying 0${}_2^{+}$ resonance of the $\alpha$ particle