A new regime for dense string networks in the one scale model with friction

We examine the compatibility between the one scale model with friction for the evolution of cosmic string networks and the Kibble mechanism for string network formation during a second order phase transition. We find a regime which connects (in a dramatically short time ∼0.1tc.) the dense string network (small network scale L∼1/Tc) created by the Kibble mechanism to the (dilute) Kibble regime (L∼t5/4) in which friction dominated strings remain till times t∗∼(MP/Tc)2tc. The enormous loss of string length implied by this result, for strings formed below the GUT scale, is due to the continued dissipative motion of the string network which follows from the one scale modelʹs identification of the typical curvature radius with the network scale and the fact that the phase transition time tc∼MPlanck/Tc2 is much larger than the damping time scale lf∼Tc2/T3. The significant implications for string mediated baryogenisis are also discussed briefly.