DEVIATIONS FROM THE HARRISON-ZELDOVICH SPECTRUM DUE TO THE QUARK-GLUON TO HADRON TRANSITION

We investigate the effect of the quark-gluon to hadron transition on t he evolution of cosmological perturbations. If the phase transitions i s first order, the sound speed vanishes during the transition, and den sity perturbations fall freely. The primordial Harrison-Zel'dovich den sity fluctuations for scales below the Hubble radius at the transition develop peaks, which grow linearly with the wavenumber, both for the hadron-photon-lepton fluid and for cold dark matter. The large peaks i n the spectrum produce cold dark matter clumps of 10(-8) to 10(-11) M. .