# On generalized Born--Infeld electrodynamics

## TL;DR

This paper investigates a generalized version of Born--Infeld electrodynamics with two parameters, analyzing vacuum birefringence effects, energy-momentum tensors, and symmetry breaking, and provides experimental bounds on the parameters.

## Contribution

It introduces a two-parameter generalization of Born--Infeld electrodynamics and explores its physical implications, including birefringence, energy-momentum tensors, and symmetry properties.

## Key findings

- Vacuum birefringence effect confirmed and quantified.
- Experimental bounds on model parameters derived from BRST and PVLAS data.
- Symmetry analyses show broken dilatation and dual symmetries.

## Abstract

The generalized Born--Infeld electrodynamics with two parameters is investigated. In this model the propagation of a linearly polarized laser beam in the external transverse magnetic field is considered. It was shown that there is the effect of vacuum birefringence, and we evaluate induced ellipticity. The upper bounds on the combination of parameters introduced from the experimental data of BRST and PVLAS Collaborations were obtained. When two parameters are equal to each other, we arrive at Born--Infeld electrodynamics and the effect of vacuum birefringence vanishes. We find the canonical and symmetrical Belinfante energy-momentum tensors. The trace of the energy-momentum tensor is not zero and the dilatation symmetry is broken. The four-divergence of the dilatation current is equal to the trace of the Belinfante energy-momentum tensor and is proportional to the parameter (with the dimension of the field strength) of the model. The dual symmetry is also broken in the model considered.