Ultra-cold neutrons in qBounce experiments as laboratory for test of chameleon field theories and cosmic acceleration

TL;DR

This paper explores how ultra-cold neutron experiments can test chameleon field theories related to cosmic acceleration, providing new bounds on the coupling constant and demonstrating their potential for fundamental physics research.

Contribution

It introduces a novel method using ultra-cold neutrons to constrain chameleon field theories, refining previous bounds on the coupling constant with experimental analysis.

Findings

Established a new upper bound on the chameleon-matter coupling constant, β ≤ 6.5×10^8.

Demonstrated the sensitivity of ultra-cold neutron experiments to scalar field effects.

Highlighted the potential of UCN experiments as laboratories for testing dark energy models.

Abstract

The accelerating expansion of the Universe, attributed to dark energy, has spurred interest in theories involving scalar fields such as chameleon field theories. These fields, which couple to matter with density-dependent effective mass, offer a promising explanation for cosmic acceleration. Experiments leveraging ultra-cold neutrons (UCNs) provide an innovative approach to testing these theories. The existence of a chameleon field, being responsible for the current phase of cosmic acceleration, is investigated by analysing a free fall of ultra-cold neutrons from the gap between two mirrors after their bouncing between these two mirrors. We analyse a deformation of the wave functions of the quantum gravitational states of ultra-cold neutrons, induced by a chameleon field, and find a new upper bound $\beta\leq6.5\times10^8$ on the chameleon-matter coupling constant $\beta$ from the unitarity condition. This result refines previous estimates and highlights the potential of ultra-cold neutron experiments as laboratories for exploring scalar field theories and fundamental physics.