Any Light Particle Searches with ALPS II: first science results

TL;DR

ALPS II's first science run set new limits on axion-like particles, demonstrating stable operation and paving the way for future sensitivity improvements in light particle searches.

Contribution

First science results from ALPS II, achieving over 20 times better limits on axion-like particles and demonstrating stable operation of a complex light-shining-through-a-wall experiment.

Findings

No evidence of axions or similar particles was found.

Set a di-photon coupling limit of 1.5e-9 1/GeV for axions below 0.1 meV.

Demonstrated stable operation and calibration of the experimental setup.

Abstract

The light-shining-through-a-wall experiment ALPS II at DESY in Hamburg searched for axions and similar lightweight particles in its first science campaign from February to May 2024. No evidence for the existence of such particles was found. For pseudoscalar bosons like the axion, with masses below about 0.1 meV, we achieved a limit for the di-photon coupling strength of 1.5e-9 1/GeV at a 95% confidence level. This is more than a factor of 20 improvement compared to all previous similar experiments. We also provide limits on photon interactions for scalar, vector and tensor bosons. An achievement of this first science campaign is the demonstration of stable operation and robust calibration of the complex experiment. Currently, the optical system of ALPS II is being upgraded aiming for another two orders of magnitude sensitivity increase.