Stated in a formal mathematical way, Bargmann's limit goes as follows. Let V : R 3 → → R : r ↦ ↦ V ( r ) be a spherically symmetric potential, such that it is piecewise continuous in r , V ( r ) = O ( 1 / r a ) for r → → 0 and V ( r ) = O ( 1 / r b ) for r → → + ∞ ∞ , where a ∈ ∈ ( 2 , + ∞ ∞ ) and b ∈ ∈ ( − − ∞ ∞ , 2 ) . If