Non-BPS Dirac-Born-Infeld solitons

We show that CPn sigma model solitons solve the field equations of a Dirac- Born-Infeld (DBI) action and, furthermore, we prove that the non-BPS solito n/anti-soliton solutions of the sigma model also solve the DBI equations. U sing the moduli space approximation we compare the dynamics of the BPS sigm a model solitons with that of the associated DBI solitons. We find that for the CP1 case the metric on the moduli space of sigma model solitons is ide ntical to that of the moduli space of DBI solitons, but for CPn with n >1 w e show that the two metrics are not equal. We also consider the possibility of similar non-BPS solitons in other DBI theories.