Theoretical investigations on the dynamical correlation in double excitations of helium by the R-matrix method

The momentum transfer dependence of double excitations of helium were studied theoretically in order to compare with our previous experimental work [Phys. Rev. Lett. 91, 193203 (2003)]. The calculation was carried out by a series of modified R-matrix codes. We elucidate the dynamical correlations in terms of the internal correlation quantum numbers K, T, and A. The generalized oscillator strength densities and Fano profile parameters q, f{sub a}, f, and S of doubly excited states {sub n}(1,0){sub 2}{sup +} {sup 1}S{sup e}, {sub n}(1,0){sub 2}{sup +} {sup 1}D{sup e}, and {sub n}(0,1){sub 2}{sup +} {sup 1}P{sup o} were reported as functions of the momentum transfer squared K{sup 2}. The present theoretical work accompanied by our previous experiment leads to a deep understanding of the optically allowed and optically forbidden double excitations of helium.