Abstract :
A four-dimensional N = 2 supersymmetric non-linear sigma-model with the Eguchi-Hanson (ALE) target space and a non-vanishing central charge is rewritten to a classically equivalent and formally renormalizable gauged ‘linear’ sigma-model over a non-compact coset space in N = 2 harmonic superspace by making use of an N = 2 vector gauge superfield as the Lagrange multiplier. It is then demonstrated that the N = 2 vector gauge multiplet becomes dynamical after taking into account one-loop corrections due to quantized hypermultiplets. This implies the appearance of a composite gauge boson, a composite chiral spinor doublet and a composite complex Higgs particle, all defined as the physical states associated with the propagating N = 2 vector gauge superfield. The composite N = 2 vector multiplet is further identified with the zero-modes of a superstring ending on a D6-brane. Some non-perturbative phenomena, such as the gauge symmetry enhancement for coincident D6-branes and the Maldacena conjecture, turn out to be closely related to our NLSM via M-theory. Our results support a conjecture about the composite nature of superstrings ending on D-branes.
