QUARKS AS TOPOLOGICAL DEFECTS - OR, WHAT IS CONFINED INSIDE A HADRON

We present a picture of confinement based on representation of constit uent quarks as pointlike topological defects. The topological charge c arried by quarks and confined in hadrons is explicitly constructed in terms of Yang-Mills variables. In 2 + 1 dimensions we are able to cons truct a local complex scalar field V(x), in terms of which the topolog ical charge is Q = -i/4pi integral d2 x epsilon(ij) partial derivative i (V partial derivative i V - c.c.) The VEV of the field V in the con fining phase is nonzero and the charge is the winding number correspon ding to homotopy group pi1(S1). Quarks carry the charge Q and therefor e are topological solitons. The phase rotation of V is generated by th e operator of magnetic flux. Unlike in QED, the U(1) magnetic flux is explicitly broken by the monopoles. This results in formation of a str ing between a quark and an antiquark. The effective Lagrangian for V i s derived in models with adjoint and fundamental quarks. This topologi cal mechanism of confinement is basically different from the one propo sed by 't Hooft in which the elementary objects are linelike domain wa lls. A baryon is described as a Y-shaped configuration of strings. In 3 + 1 dimensions the explicit expression for V, and therefore a detail ed picture, is not available. However, assuming the validity of the sa me mechanism we point out several interesting qualitative consequences .