TOPOLOGICAL CONFORMAL FIELD THEORY WITH A RATIONAL W POTENTIAL AND THE DISPERSIONLESS KP HIERARCHY

We present a new class of topological conformal field theories (TCFTs) characterized by a rational W potential, which includes the minimal models of A and D types as its subclasses. An explicit form of the W potential is found by solving the underlying dispersionless KP hierarchy in a particular small phase space. We also discuss the dispersionless KP hierarchy in large phase spaces by reformulating the hierarchy, and show that the W potential takes a universal form, which does not depend on a specific form of the solution in a large space.