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, fa, f, and S of doubly excited states n(1,0)2+1Se, n(1,0)2+1De, and n(0,1)2+1Po were reported as functions of the momentum transfer squared K2. 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