Gauge dependence of nonrelativistic calculations of deuteron photodisintegration

Extension of the Siegert theorem for photon emission

“…Beyond the long wavelength approximation, the Siegert transformation of the electric term can not be performed fully [2] and is not unique any more [3]. Even when the gauge is fixed, the electric multipoles of the electromagnetic field can be written in an infinity of ways as [3] A Eλ µ (r) = ∇Φ λµ (r) + A ′Eλ µ (r).…”

“…Even when the gauge is fixed, the electric multipoles of the electromagnetic field can be written in an infinity of ways as [3] A Eλ µ (r) = ∇Φ λµ (r) + A ′Eλ µ (r).…”

“…Physical results would be independent of the choice of Φ λµ as long as the term involving A ′Eλ µ is taken into account, if exact energies and wave functions and currents consistent with the Hamiltonian are used [3].…”

“…The situation is very different in photonuclear physics where higher photon energies are used [3]. In this case, different extensions of the Siegert theorem have been studied and compared.…”

“…Some aspects of their approach were anticipated by Foldy [6]. These variants are said to differ by the 'gauge' by some authors [3] although they are derived within the same Coulomb gauge.…”