Non-linear supersymmetry and intersecting D-branes

Abstract

We study the non-linear realization of supersymmetry. We classify all lower dimensional operators, describing effective interactions of the Goldstino with Standard Model fields. Besides a universal coupling to the energy momentum tensor of dimension eight, there are additional model dependent operators whose strength is not determined by non-linear supersymmetry, within the effective field theory. Their dimensionality can be lower than eight, starting with dimension six, leading in general to dominant effects at low energies. We compute their coefficients in string models with D-branes at angles. We find that the Goldstino decay constant is given by the total brane tension, while the various dimensionless couplings are independent from the values of the intersection angles.