Hiding in Plain Sight, the electroweak ${\eta }_W$

The presence of a topological susceptibility in the electroweak sector of the Standard Model implies the existence of a pseudoscalar state in the spectrum, ${\eta }_W$. We show that, within the Standard Model, no new particle is required to form this state. We identify the ${\eta }_W$ state with the CP-odd linear combination of the ground states of hydrogen and antihydrogen atoms.