We investigate a new mechanism for the cosmological QCD phase transition:
inhomogeneous nucleation. The primordial temperature fluctuations, measured to
be δT/T∼10−5, are larger than the tiny temperature interval, in
which bubbles would form in the standard picture of homogeneous nucleation.
Thus the bubbles nucleate at cold spots. We find the typical distance between
bubble centers to be a few meters. This exceeds the estimates from homogeneous
nucleation by two orders of magnitude. The resulting baryon inhomogeneities may
affect primordial nucleosynthesis.Comment: Version to appear in Phys. Rev. Lett., 4 pages, 1 figure. Difference
to heterogeneous nucleation emphasized, amplitude of temperature fluctuations
analyzed in more detail, new length scale l_heat introduced, more complicated
geometry of baryon number discussed shortly (relevant for low values of
l_heat
