Experimental constraints on polarizability corrections to hydrogen hyperfine structure

We present a state-of-the-art evaluation of the polarizability corrections--the inelastic nucleon corrections--to the hydrogen ground-state hyperfine splitting using analytic fits to the most recent data. We find a value Delta(pol)=1.3+/-0.3 ppm. This is 1-2 ppm smaller than the value of Delta(pol) deduced using hyperfine splitting data and elastic nucleon corrections obtained from modern form factor fits.