DELTA(1232) AND THE POLARIZABILITIES OF THE NUCLEON

Previous calculations of the polarizabilities of the nucleon within th e framework of heavy baryon chiral perturbation theory have included t he contribution of the Delta(1232) only in its effects on various cont act terms or have been performed in chiral SU(3) where systematic erro rs are difficult to control. Herein, we perform a corresponding calcul ation in chiral SU(2) wherein Delta(1232) is treated as an explicit de gree of freedom and the expansion is taken to third order in soft mome nta the pion mass, and the quantity M-Delta-M-N, collectively denoted epsilon. We present the results of a systematic 0(epsilon(3)) calculat ion of forward Compton scattering off the nucleon, extract the electri c polarizability <(alpha(E))over bar>, the magnetic polarizability <(b eta(M))over bar>, and the spin polarizability gamma, and compare with available information from experiments and from previous calculations. Concluding with a critical discussion of our results. we point out th e necessity of a future O(epsilon(4)) calculation.