The PVLAS experiment: measuring vacuum magnetic birefringence and dichroism with a birefringent Fabry-Perot cavity

TL;DR

The PVLAS experiment measures vacuum magnetic birefringence and dichroism using a high finesse Fabry-Perot cavity, providing new limits on hypothetical particles and neutrino charges, advancing the search for quantum vacuum effects.

Contribution

This work reports the latest experimental results of PVLAS, including analysis of mirror birefringence and new constraints on axion-like particles, milli-charged particles, and neutrino charges.

Findings

Set new limits on vacuum magnetic birefringence.

Excluded regions in parameter space for axion-like and milli-charged particles.

Established laboratory limits on neutrino charge.

Abstract

Vacuum magnetic birefringence was predicted long time ago and is still lacking a direct experimental confirmation. Several experimental efforts are striving to reach this goal, and the sequence of results promises a success in the next few years. This measurement generally is accompanied by the search for hypothetical light particles that couple to two photons. The PVLAS experiment employs a sensitive polarimeter based on a high finesse Fabry-Perot cavity. In this paper we report on the latest experimental results of this experiment. The data are analysed taking into account the intrinsic birefringence of the dielectric mirrors of the cavity. Besides the limit on the vacuum magnetic birefringence, the measurements also allow the model-independent exclusion of new regions in the parameter space of axion-like and milli-charged particles. In particular, these last limits hold also for all types of neutrinos, resulting in a laboratory limit on their charge.