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 Δpol=1.3±0.3 ppm. This is 1-2 ppm smaller than the value of Δpol deduced using hyperfine splitting data and elastic nucleon corrections obtained from modern form factor fits