An Improved Torsion Balance Test of the Equivalence Principle Towards the Sun

TL;DR

This paper reports an improved torsion balance experiment that sets tighter limits on violations of the Equivalence Principle towards the Sun, enhancing previous experimental constraints by a factor of four.

Contribution

The study introduces a more sensitive torsion balance method to test the Equivalence Principle towards the Sun, achieving significantly improved limits on potential violations.

Findings

95% confidence limits on violations: η_{⊙, Be-Al} ≤ 2.1 × 10^{-13}

Fourfold improvement over previous results towards the Sun

Approximately 20% better than prior torsion balance tests regardless of source

Abstract

We search for violations of the Equivalence Principle towards the Sun using a rotating torsion balance apparatus. We set 95\%-confidence limits on violations with beryllium and aluminum test bodies of $\eta_{\odot, Be-Al} \leq 2.1 \times 10^{-13}$. These results are a factor of four improvement of previously reported results towards the Sun and a $\sim20\%$ improvement on previous torsion balance tests regardless of source.