Abstract
Bulk properties, spectrum, and nuclear response of 8He are investigated within the equation of motion phonon method, which generates an orthonormal basis of n-phonon states (n = 0, 1, 2, 3 ...) whose constituents are Tamm-Dancoff phonons. The basis is free of any contamination induced by the center-of-mass motion, in virtue of a procedure exploiting the singular value decomposition of rectangular matrices.
A self-consistent calculation is performed within a space spanned by a basis of n-phonon states up to n = 3 using a potential derived from the chiral effective field theory. The Hartree-Fock single-particle states are obtained from a harmonic-oscillator space including all major shells up to Nmax= 12.
The calculation is exact up ton = 2, whereas the three-phonon (n = 3) states are assumed to be composed of noninteracting n = 1 and n = 2 constituent phonons. It yields bulk and spectroscopic observables consistent with the available experimental data and provides an electric dipole response exhibiting distinctive signatures.