Generalized Gelfand-Dikii equation and solitonic electric fields for fermionic Schwinger pair production

In previous work on Schwinger pair creation in purely time-dependent fields, it was shown how to construct solitonic electric fields that do not create scalar pairs with an arbitrary fixed momentum. We show that this construction can be adapted to the fermionic case in two inequivalent ways, both closely related to supersymmetric quantum mechanics for reflectionless potentials, and both leading to the vanishing of the density of created pairs at certain values of the Poschl-Teller like index p of the associated Schrodinger equation. For one of them, we are able to demonstrate that the pair noncreation can be interpreted as a quantum interference effect using the phase-integral formalism. Asymptotically for large p, here scalar particles are not created for integer p and fermions are not created for half-integer p. Thus, for any given momentum we can construct electric fields that create scalar particles but not spinor particles, and vice versa. In the scalar QED case, the solitonic fields had originally been found using the Gelfand-Dikii equation, which is related to the resolvent of the mode equation, and through it to the (generalized) KdV equation [I. M. Gelfand and L. A. Dikii, Asymptotic behavior of the resolvent of Sturm-Liouville equations and the Algebra of the Korteweg-De Vries equations, Russ. Math. Surv. 30, 5 (1975)]. This motivates us to develop for the spinor QED case, too, an evolution equation that can be considered as a fermionic generalization of the Gelfand-Dikii equation.

Automated summary

In previous work, it was shown how to construct solitonic electric fields that do not create scalar pairs with a fixed momentum in purely time-dependent fields. It is now discovered that this construction can be adapted to the fermionic case in two inequivalent ways. Both adaptations are closely related to supersymmetric quantum mechanics for reflectionless potentials and lead to the vanishing of the density of created pairs at certain values of the associated Schrodinger equation. One of the adaptations interprets the noncreation of pairs as a quantum interference effect using the phase-integral formalism. It is also found that for large values of the index p of the associated Schrodinger equation, scalar particles are not created for integer p and fermions are not created for half-integer p. As a result, it is possible to construct electric fields that create scalar particles but not spinor particles, and vice versa, for any given momentum. The discovery of solitonic fields in scalar quantum electrodynamics using the Gelfand-Dikii equation motivates the development of a fermionic generalization of this equation for spinor quantum electrodynamics.