Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Axions are hypothetical elementary particles proposed as a solution to the strong CP problem in quantum chromodynamics. They are also considered potential candidates for dark matter.
5 Must Know Facts For Your Next Test
Axions were first proposed by Roberto Peccei and Helen Quinn in 1977.
They interact very weakly with ordinary matter, making them difficult to detect.
Axions could account for a significant portion of dark matter in the universe.
Experiments such as ADMX (Axion Dark Matter Experiment) are designed to detect axions using microwave cavities.
The mass of axions is still uncertain but is predicted to be extremely low, typically in the range of microelectronvolts (μeV).
A form of matter that does not emit light or energy and is thought to constitute approximately 27% of the universe's mass-energy content.
Strong CP Problem: A theoretical issue in particle physics concerning why quantum chromodynamics (QCD) does not seem to violate the combined symmetry of charge conjugation (C) and parity (P).
Quantum Chromodynamics (QCD): \( Quantum \) field theory describing the interactions between quarks and gluons which constitute protons, neutrons, and other hadronic particles.