Quintom evolution in power-law potentials
  We investigate quintom evolution in power-law potentials. We extract the
early-time, tracker solutions, under the assumption of matter domination.
Additionally, we derive analytical solutions at intermediate times, that is at
low redshifts, which is the period during the transition from matter to
dark-energy domination. A comparison with exact evolution reveals that the
tracker solutions are valid within 98% for z>1.5, while the intermediate ones
are accurate within 98% up to z=0.5. Using these expressions we extract two new
w-parametrizations, one in terms of the redshift and one in terms of the
dark-energy density-parameter, and we present various quintom evolution
sub-classes, including quintessence-like or phantom-like cases, realization of
the -1-crossing, and non-monotonic w-evolution.
