Comments on the polarization of the quenched radiation from the2sstate of hydrogen

This paper examines two theoretical aspects of the measurement of polarization of the quenched radiation which comes from the application of a weak electric field to the $2s$ state of hydrogen. Specifically, it outlines the justification of the Bethe-Lamb phenomenological analysis of this problem from the external field approximation of quantum electrodynamics. Further, it includes the lowest-order effects of the J-breaking part of the hyperfine structure in Rayleigh-Schr\"odinger perturbation theory. While it was expected that these terms would contribute to the polarization fraction a correction to the lowest order of the relative size of the ratio of the hyperfine splittings to the fine-structure splitting of the $n=2$ state or about one part in 10³, cancellations occur and these J-breaking terms give a correction in the fourth place of the polarization fraction.