Subelectronvoltc2

Subelectronvoltc2 (sub-eV/c^2) is a unit of mass used in particle physics to describe the mass of particles that are much lighter than the electron. The term "sub-eV/c^2" is derived from the relationship between mass and energy in special relativity, where E = mc^2. One electronvolt (eV) is the energy gained by a single electron when it is accelerated through an electric potential difference of one volt. Therefore, sub-eV/c^2 refers to particles with masses much smaller than the mass of an electron, which is approximately 0.511 MeV/c^2.

Particles with sub-eV/c^2 masses are often referred to as ultralight particles. These particles are of significant interest in various fields of physics, including cosmology, astrophysics, and particle physics. They are hypothesized to play a role in dark matter, which is believed to make up a significant portion of the universe's mass but has not been directly observed. Ultralight particles could also be involved in the formation of cosmic structures and the evolution of the universe.

The detection and study of sub-eV/c^2 particles pose significant experimental challenges due to their extremely low masses and the corresponding low energies involved. Various experimental techniques, such as precision measurements of fundamental constants, searches for deviations from standard physics in low-energy systems, and the study of cosmic microwave background radiation, are employed to search for evidence of these particles.