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arXiv · 2509.15912

Hiding in Plain Sight, the electroweak $\eta_W$

Giacomo Cacciapaglia·Francesco Sannino·Jessica Turner
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Abstract

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.

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Giacomo Cacciapaglia, Francesco Sannino, Jessica Turner. 2025-09-19. Hiding in Plain Sight, the electroweak $\eta_W$. https://arxiv.org/abs/2509.15912

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