Open string in background non-Abelian field

The interaction of charged strings with an external field is of interest in connection with the low-energy limit in string field theory. The theory of a charged string interacting with an external electromagnetic field leads to an effective Born–Infeld action for the external field [1], i.e., the external field is restricted, this being a consequence of the nonlinearity. The present paper studies dynamics of a string in an external Yang–Mills field when the string carries a non-Abelian charge at its ends. The action function is found. A boundary-value problem and equations of motion are derived from the variational principle. Gauge conditions for such a system are proposed, and a particular solution corresponding to motion of the string in such a field is discussed.