Relic abundance

In cosmology, (temperature scaled) abundance of a particle is defined by

$Y\equiv n/T^{3},$,

where $n$ is the number density:

$n\equiv N/V$,

that is, number of particles per physical volume (not the comoving volume).

The relic abundance of a particle is shown by $Y_{\infty }$ indicates the asymptotic value of abundance of a species of a particle which it will reach after its freaz out.

The current accepted abundance values for protons, neutrons, photons, neutrinos, and WIMPs can be found in the table bellow (which hopefully will be created by a knowledgeable and kind editor).