For 10points, name this quantity symbolized A, whose curl gives the magnetic field.
The commutator of this quantity with momentum appears in the operator for dipole transition matrixelements. The inverse Fourier transform of this function is used to derive the Darwin interaction term inthe Lagrangian for a particle in a field. This quantity is equal to a constant times an integral of the currentdensity over volume in the definition of retarded potentials. The importance of this quantity was shown inan experiment in which a beam of electrons were split while travelling (*) around a solenoid, causing themto acquire a 180 degree phase shift named for Berry. This quantity, which is added to the gradient of an arbitraryfunction in a gauge transformation, was shown to have physical relevance by the Aharonov-Bohm effect. For 10points, name this quantity symbolized A, whose curl gives the magnetic field.
The commutator of this quantity with momentum appears in the operator for dipole transition matrixelements.
Vector potential