Neutron limit on the strongly-coupled chameleon field

Area of Science:

• Cosmology
• Particle Physics
• Quantum Mechanics

Background:

• The accelerated expansion of the Universe is attributed to dark energy, a major unsolved problem in cosmology.
• Chameleon dark energy theory proposes a self-interacting scalar field that couples to matter, featuring a screening mechanism.
• This screening suppresses the field in dense matter but allows it to be present in vacuum for laboratory experiments.

Purpose of the Study:

• To establish the most stringent upper bound on the free neutron-chameleon coupling in the strongly coupled limit.
• To investigate the chameleon dark energy theory using laboratory-based experiments.

Main Methods:

• Utilized neutron interferometric techniques to detect the chameleon field.
• Measured the relative phase shift induced by the chameleon field along a neutron path.
• Actively modulated the chameleon field amplitude by varying pressure in a dual-chamber aluminum cell.

Main Results:

• Reported a 95% confidence level upper bound on the neutron-chameleon coupling parameter, beta.
• Achieved bounds ranging from beta < 4.7 x 10^6 (n=1) to beta < 2.4 x 10^7 (n=6).
• Demonstrated an order of magnitude improvement over previous free neutron limits for intermediate values of n.

Conclusions:

• The experiment provides the most stringent constraints to date on neutron-chameleon coupling.
• Future experiments can explore the full parameter space of chameleon dark energy.
• This work advances our understanding of dark energy's physical origin and its potential interactions.