The first search for sub-eV scalar fields via four-wave mixing at a quasi-parallel laser collider

TL;DR

This paper reports the first experimental search for sub-eV scalar fields coupling to photons using a novel four-wave mixing technique with a quasi-parallel laser collider, setting new upper limits on their coupling strength.

Contribution

It introduces a new experimental approach combining two-color laser fields for resonant detection of sub-eV scalar fields in vacuum.

Findings

No significant four-wave mixing signal was observed.

Upper limits on scalar-photon coupling were established.

Method is extendable to higher intensity laser systems.

Abstract

A search for sub-eV scalar fields coupling to two photons has been performed via four-wave mixing at a quasi-parallel laser collider for the first time. The experiment demonstrates the novel approach to search for resonantly produced sub-eV scalar fields by combining two-color laser fields in the vacuum. The aim of this paper is to provide the concrete experimental setup and the analysis method based on specific combinations of polarization states between incoming and outgoing photons, which is extendable to higher intensity laser systems operated at high repetition rates. No significant signal of four-wave mixing was observed by combining a $0.2\mu$J/0.75ns pulse laser and a 2mW CW laser on the same optical axis. Based on the prescription developed for this particular experimental approach, we obtained the upper limit at a confidence level of 95% on the coupling-mass relation.