Abstract :
We consider the boundary states which describe D-branes in a constant B-field background. We show that the two-form field Φ, which interpolates commutative and noncommutative descriptions of D-branes, can be interpreted as the invariant field strength in the T-dual picture. We also show that the extended algebra parametrized by θ and Φ naturally appears as the commutation relations of the original and the T-dual coordinates.
