It is shown that in nuclear matter at $Z=0\mathrm{}$ (neutron star) at a density $n_1<n_{\mathrm{nucl}}$ a ${\pi }^0$ condensate appears. Nearly at the same density an electrically neutral ${\pi }^{+}$, ${\pi }^{-}$ condensate arises. The ${\pi }^{-}$ condensate assumed by other workers apparently does not arise even at very high densities.

• Received 17 April 1973

DOI:https://doi.org/10.1103/PhysRevLett.31.257