Test of the theoretical hyperfine structure of the molecular hydrogen ion at the 1-ppm level

Vladimir I. Korobov, Jeroen C. J. Koelemeij, Laurent Hilico +1

We revisit the $m{\alpha }^6(m/M)$ order corrections to the hyperfine splitting in the H${}_2^{+}$ ion, and find a hitherto unrecognized second-order relativistic contribution associated wit…