arXiv subjects

Jonah Ruhl

Publications and source records attributed to Jonah Ruhl.

2 recordsLinked to original sources

arXiv2026

Causal self-dual nonlinear electrodynamics from the Born-Infeld theory

Recently we have proposed a new auxiliary-field formulation for self-dual nonlinear electrodynamics (NLED) which makes use of two building blocks: (i) a seed self-dual theory $L(F_{\mu\nu};g)$, where $F_{\mu \nu}$ is the electromagnetic field strength and $g$ a duality-invariant coupling constant; and (ii) a scalar potential $W(\psi)$. Our formulation is based on the Lagrangian $ \mathfrak{L}(F_{\mu\nu};\psi) = L(F_{\mu\nu};\psi) + W(\psi)$, where $\psi$ is an auxiliary scalar field. Integrating out $\psi$, using its equation of motion, one obtains a $\mathsf{U}(1)$ duality-invariant NLED. Different self-dual NLEDs are derived by choosing different potentials $W(\psi)$. In the case that the seed Lagrangian defines the Born-Infeld theory, in this paper we demonstrate that the resulting models for self-dual NLED are causal and provide a general solution of the self-duality equation. We also elaborate on the procedure to relate our formulation to that developed by Russo and Townsend.

hep-th↗

arXiv2025

Generalisations of the Russo-Townsend formulation

As a generalisation of the recent construction by Russo and Townsend, we propose a new approach to generate $\mathsf{U}(1)$ duality-invariant models for nonlinear electrodynamics. It is based on the use of two building blocks: (i) a fixed (but otherwise arbitrary) model for self-dual nonlinear electrodynamics with Lagrangian $L(F_{\mu\nu};g)$ depending on a duality-invariant parameter $g$; and (ii) an arbitrary potential $W(\psi)$, with $\psi$ an auxiliary scalar field. It turns out that the model $\mathfrak{L}(F_{\mu\nu};\psi) = L(F_{\mu\nu};\psi) + W(\psi)$ leads to a self-dual theory for nonlinear electrodynamics upon elimination of $\psi$. As an illustration, we work out two examples in which the seed Lagrangian $L(F_{\mu\nu};g)$ corresponds to the Born-Infeld model and two particular potentials $W(\psi)$ are chosen such that integrating out $\psi$ gives: (i) the ModMaxBorn theory; and (ii) the ModMax theory. We also briefly discuss supersymmetric generalisations of the proposed formulation.

hep-th↗