  We construct a theoretical model for equilibrium distribution of workers
across sectors with different labor productivity, assuming that a sector can
accommodate a limited number of workers which depends only on its productivity.
A general formula for such distribution of productivity is obtained, using the
detail-balance condition necessary for equilibrium in the Ehrenfest-Brillouin
model. We also carry out an empirical analysis on the average number of workers
in given productivity sectors on the basis of an exhaustive dataset in Japan.
The theoretical formula succeeds in explaining the two distinctive
observational facts in a unified way, that is, a Boltzmann distribution with
negative temperature on low-to-medium productivity side and a decreasing part
in a power-law form on high productivity side.
