Baryon asymmetry
= Baryon asymmetry
{title2=$\eta_B=(n_B-n_{\bar B})/n_\gamma$}
{wiki}
The <baryon asymmetry> is an excess of <baryons> over <antibaryons>. Here $n_B-n_{\bar B}$ counts net <baryon number> per unit volume, including the baryons bound in <atomic nuclei>. It is dynamically generated by <baryogenesis>. Once the <antibaryon> abundance is negligible, its photon-normalized value agrees with the usual <baryon-to-photon ratio>.