Effective action for quantum Hall skyrmions

Recently, an O(3) type of effective action was proposed for the quantum Hall ferromagnet, which accounts for bag formation observed in microscopic Hartree- Fock calculations. We apply this action in the soliton sector and compare with Hartree-Fock results. We find good agreement over the whole parameter range where skyrmions exist. The standard minimal O(3) model cannot explain the bag and has further shortcomings connected with that fact.