SKYRMION QUANTITATION AND THE DECAY OF THE DELTA

We present the complete solution to the so-called ''Yukawa problem'' o f the Skyrme model. This refers to the perceived difficulty of reprodu cing, purely from soliton physics, the usual pseudovector pion-nucleon coupling, echoed by pion coupling to the higher-spin/isospin baryons (I=J=3/2,3/2,...,N-c/2) in a manner fixed by large-N-c group theory. T he solution involves surprisingly elegant interplay between the classi cal and quantum properties of a new configuration: the rotationally im proved Skyrmion. This is the near-hedgehog solution obtained by minimi zing the usual Skyrmion mass functional augmented by an all-important (iso)rotational kinetic term. The numerics are pleasing: a Delta decay width within a few MeV of its measured value, and, furthermore, the h igher-spin baryons (I=J greater than or equal to 5/2) with widths so l arge (Gamma > 800 MeV) that these undesirable large-N-c artifacts effe ctively drop out of the spectrum, and pose no phenomenological problem . Beyond these specific results, we ground the Skyrme model in the Fey nman path integral, and set up a transparent collective coordinate for malism that makes maximal use of the 1/N-c expansion. This approach el ucidates the connection between Skyrmions on the one hand, and Feynman diagrams in an effective held theory on the other.