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The origin of the plus and minus character of the ¹P and ³P doubly excited states of helium which converge to the $n=2$ level is investigated in the close-coupling approximation. It is found that the close-coupling wave functions do exhibit the plus and minus character, and that the widths of these states are related to their plus and minus character in the case of the ¹P, but not for ³P.
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J. H. Macek (1966) studied this question.
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