  We present a quantitative semi-classical theory for the non-equilibrium
dynamics of transverse Ising chains after quantum quenches, in particular
sudden changes of the transverse field strength. We obtain accurate predictions
for the quench dependent relaxation times and correlation lengths, and also
about the recurrence times and quasiperiodicity of time dependent correlations
in finite systems with open or periodic boundary conditions. We compare the
quantiative predictions of our semi-classical theory (local magnetization,
equal time bulk-bulk and surface-to-bulk correlations, and bulk
autocorrelations) with the results from exact free fermion calculations and
discuss the range of applicability of the semi-classical theory and possible
generaliztaions and extensions.
