Total 4He photoabsorption cross section reexamined: Correlated versus Effective Interaction Hyperspherical Harmonics

Two conceptually different hyperspherical harmonics expansions are used for the calculation of the total 4He photoabsorption cross section. Besides the well-known method of correlated hyperspherical harmonics, the recently introduced effective interaction approach for the hyperspherical formalism is applied. Semirealistic NN potentials are employed and final-state interaction is fully taken into account via the Lorentz integral transform method. The results show that the effective interaction leads to a very good convergence, while the correlation method exhibits a less rapid convergence in the giant dipole resonance region. The rather strong discrepancy with the experimental photodisintegration cross sections is confirmed by the present calculations.