fine structure constant, α

Atomic fundamental physical constant, $α = μ 0 e 2 c 0 2 h = 7.297 353 08 33 × 10 −3$ , where $μ 0$ is the permeability of vacuum, $e$ the elementary charge, $h$ the Planck constant, and $c 0$ the speed of light.

Source:

CODATA Bull. 1986, 63, 1