Equivalence Principle Violations and Couplings of a Light Dilaton

TL;DR

This paper explores how a light dilaton-like scalar could cause violations of the equivalence principle, analyzing its couplings and implications for experimental tests.

Contribution

It introduces a parameterization of dilaton couplings and highlights the dominant parameters affecting equivalence principle violations.

Findings

Dilaton-quark-mass coupling leads to significant E"p violations

Violations scale as A^{-1/3} with atomic number

Framework informs experimental sensitivity comparisons

Abstract

We consider possible violations of the equivalence principle through the exchange of a light `dilaton-like' scalar field. Using recent work on the quark-mass dependence of nuclear binding, we find that the dilaton-quark-mass coupling induces significant equivalence-principle-violating effects varying like the inverse cubic root of the atomic number - A^{-1/3}. We provide a general parameterization of the scalar couplings, but argue that two parameters are likely to dominate the equivalence-principle phenomenology. We indicate the implications of this framework for comparing the sensitivities of current and planned experimental tests of the equivalence principle.