Surface defects from fractional branes. Part II

A generic half-BPS surface defect of N= 4 supersymmetric U(N ) Yang- Mills theory is described by a partition of N = n1 + . . . + nM and a set of 4M continuous parameters. We show that such a defect can be realized by nI stacks of fractional D3-branes in Type II B string theory on a ZM orbifold background in which the brane world-volume is partially extended along the orbifold directions. In this set up we show that the 4M continuous parameters correspond to constant background values of certain twisted closed string scalars of the orbifold. These results extend and generalize what we have presented for the simple defects in a previous paper.