The Drell-Hearn Sum Rule at Order Alpha**3

The Drell-Hearn-Gerasimov-Iddings (DHGI) sum rule for electrons is evaluated at order $\alpha^3$ and shown to agree with the Schwinger contribution to the anomalous magnetic moment.Comment: 3 pages, 1 figur

Proton and neutron polarized structure functions from low to high Q**2

Phenomenological parameterizations of proton and neutron polarized structure functions, g1p and g1n, are developed for x > 0.02 using deep inelastic data up to ~ 50 (GeV/c)**2 as well as available experimental results on photo- and electro-production of nucleon resonances. The generalized Drell-Hearn-Gerasimov sum rules are predicted from low to high values of Q**2 and compared with proton and neutron data. Furthermore, the main results of the power correction analysis carried out on the Q**2-behavior of the polarized proton Nachtmann moments, evaluated using our parameterization of g1p, are briefly summarized.Comment: Proceedings of the II International Symposium on the Gerasimov-Drell-Hearn sum rule and the spin structure of the nucleon, Genova (Italy), July 3-6, 200

Drell-Hearn-Gerasimov Sum Rule for the Nucleon in the Large-N_c Limit

We show that the Drell-Hearn-Gerasimov sum rule for the nucleon is entirely saturated by the \Delta resonance in the limit of a large number of colors, N_c \to \infty. Corrections are at relative order 1/N_c^2.Comment: 6 pages, latex, no figure

The GDH Sum Rule and Related Integrals

The spin structure of the nucleon resonance region is analyzed on the basis of our phenomenological model MAID. Predictions are given for the Gerasimov-Drell-Hearn sum rule as well as generalized integrals over spin structure functions. The dependence of these integrals on momentum transfer is studied and rigorous relationships between various definitions of generalized Gerasimov-Drell-Hearn integrals and spin polarizabilities are derived. These results are compared to the predictions of chiral perturbation theory and phenomenological models.Comment: 15 pages LaTeX including 5 figure

The Gerasimov-Drell-Hearn Sum Rule and Current Algebras

The status of the Gerasimov-Drell-Hearn sum rules for polarized inclusive photo-production on nucleons is reviewed. It is shown that results from currently available data compare favorably with an estimate based on an extended current algebra. Implications for integrals of spin-dependent structure functions are also briefly discussed.Comment: 8 Page

The Gerasimov-Drell-Hearn sum rule and the infinite-momentum limit

We study the current-algebra approach to the Gerasimov-Drell-Hearn sum rule, paying particular attention to the infinite-momentum limit. Employing the order-alpha^2 Weinberg-Salam model of weak interactions as a testing ground, we find that the legitimacy of the infinite-momentum limit is intimately connected with the validity of the naive equal-times algebra of electric charge densities. Our results considerably reduce the reliability of a recently proposed modification of the Gerasimov-Drell-Hearn sum rule, originating from an anomalous charge-density algebra.Comment: 12 pages; 6 figures; LaTeX; submitted to Z.Phys.

Chapter I - Landing in Japan

In which our three heroes -- William E. Griffis, missionary; Edward S. Morse, scientist; and Lafcadio Hearn, writer -- find during their first weeks in Japan that this Asian country lives up to some of their preconceptions, violates others, and altogether proves to be a more complicated, perplexing, challenging, and interesting place than they had imagined

Novel analysis of chiral loop effects in the generalized Gerasimov-Drell-Hearn sum rule

We study the chiral loop corrections to the generalized Gerasimov-Drell-Hearn sum rule of the nucleon for finite photon virtuality in the framework of a Lorentz-invariant formulation of baryon chiral perturbation theory. We perform a complete one-loop calculation and obtain significant differences to previously found results based on the heavy baryon approach for the proton and neutron spin-dependent forward Compton amplitudes.Comment: 7 pp, 3 figs, published version, extended discussion, minor revision