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Centro de Astrofísica da Universidade do Porto

Scale-invariant string evolution with friction

C. J. A. P. Martins, E. P. S. Shellard

Abstract
We study the effects of friction on the scaling evolution of string networks in condensed matter and cosmological contexts. We derive a generalized "one-scale" model with the string correlation length L and velocity v as dynamical variables. In nonrelativistic systems, we obtain a well-known L~t1/2 law, showing that loop production is important. For electroweak cosmic strings, we show transient damped epoch scaling with L~t5/4 (or, in the matter era, L~t3/2). A low initial density implies an earlier period with L~t1/2. For GUT strings, the approach to linear scaling L~t is faster than previously estimated.

Physical Review D
Volume 53, Page R575
January 1996

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