Long-term dynamics of cosmological axion strings
  We present results of new field-theoretic simulation of cosmological axion
strings, which are eight times longer than previous ones. We have upgraded our
simulation of physical strings in Hiramatsu et al. (2011) in terms of the
number of grids as well as the suite of analysis methods. These improvements
enable us to monitor a variety of quantities characterizing the dynamics of the
physical string network for the longest term ever. Our extended simulations
have revealed that global strings do not evolve according to the scaling
solution but its scaling parameter, or the number of long strings per horizon,
increases logarithmically in time. In addition, we have also found that the
scaling parameter shows nontrivial dependence on the breaking scale of the
Peccei-Quinn symmetry.
