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Bibliographic Details
Main Authors: Cacciapaglia, Giacomo, Sannino, Francesco, Turner, Jessica
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2510.14104
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Table of Contents:
  • The presence of a topological susceptibility in the electroweak sector of the Standard Model motivates the existence of a good quality weak axion $a_W$, associated with the spontaneous breaking of $B\!+\!L$. Its anomalous couplings and tiny mass, generated from electroweak instantons, render $a_W$ photophobic. We find that the strongest bound on the associated decay constant, $f_W$, stems from a loop-induced coupling to electrons, leading to $f_W \gtrsim 1000$ TeV from stellar cooling. Spontaneous breaking of the abelian ${B\!+\!L}$ symmetry induces proton decay via higher dimensional operators controlled by a new physics scale, $Λ$. Existing Super-Kamiokande limits on these decay channels constrain the new physics scale to be $Λ\gtrsim 10^{12}$ GeV. The characteristic channel $p\to e^+ a_W$ and other possible operators mediating interactions with the Standard Model fields yield signals which are not detectable within the allowed parameter space. Future proton decay searches at the next-generation of neutrino experiments offer the most promising avenues to test the good qualities of the weak axion paradigm.