The spin polarizabilities of the nucleon describe how the spin of the nucleon responds to an incident polarized photon. The most model-independent way to extract the nucleon spin polarizabilities is through polarized Compton scattering. Double-polarized Compton scattering asymmetries on the proton were measured in the Delta(1232) region using circularly polarized incident photons and a transversely polarized proton target at the Mainz Microtron. Fits to asymmetry data were performed using a dispersion model calculation and a baryon chiral perturbation theory calculation, and a separation of all four proton spin polarizabilities in the multipole basis was achieved. The analysis based on a dispersion model calculation yields gamma(E1E1) = -3.5 +/- 1.2, gamma(M1M1) = 3.16 +/- 0.85, gamma(E1M2) = -0.7 +/- 1.2, and gamma(M1E2) = 1.99 +/- 0.29, in units of 10(-4) fm(4).
- EFFECTIVE-FIELD THEORY