Symmetries and conservation laws in non-Hermitian field theories

Abstract

Anti-Hermitian mass terms are considered, in addition to Hermitian ones, for PT-symmetric complex-scalar and fermionic field theories. In both cases, the Lagrangian can be written in a manifestly symmetric form in terms of the PT-conjugate variables, allowing for an unambiguous definition of the equations of motion. After discussing the resulting constraints on the consistency of the variational procedure, we show that the invariance of a non-Hermitian Lagrangian under a continuous symmetry transformation does not imply the existence of a corresponding conserved current. Conserved currents exist, but these are associated with transformations under which the Lagrangian is not invariant and which reflect the well-known interpretation of PT-symmetric theories in terms of systems with gain and loss. A formal understanding of this unusual feature of non-Hermitian theories requires a careful treatment of Noether's theorem, and we give specific examples for illustration.

Discussions extended

References in corpus (4)

• Exactly solvable PT-symmetric Hamiltonian having no Hermitian counterpart
• Critical behavior of the PT-symmetric $i{\varphi }^3$ quantum field theory
• Foldy-Wouthuysen transformation for non-Hermitian Hamiltonians
• Infinitely many inequivalent field theories from one Lagrangian

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