Measurement of the Q² Dependence of the Deuteron Spin Structure Function g1 and its Moments at Low Q² with CLAS.

We measured the g1 spin structure function of the deuteron at low Q², where QCD can be approximated with chiral perturbation theory (χPT). The data cover the resonance region, up to an invariant mass of W≈1.9 GeV. The generalized Gerasimov-Drell-Hearn sum, the moment Γd1 and the spin polarizability γd0 are precisely determined down to a minimum Q² of 0.02 GeV² for the first time, about 2.5 times lower than that of previous data. We compare them to several χPT calculations and models. These results are the first in a program of benchmark measurements of polarization observables in the χPT domain. [ABSTRACT FROM AUTHOR]