Electroweak η w meson
Gia Dvali, Archil B. Kobakhidze, Otari Sakhelashvili · Physical review. D/Physical review. D. · 2025
We argue that the Standard Model is accompanied by a new pseudoscalar degree of freedom, η w meson, which cancels the topological susceptibility of the electroweak vacuum and gets its mass from this effect. The prediction is based on the analyticity properties of the Chern-Simons correlator combined with the basic features of gravity. Depending on the quality level of the U ( 1 ) B + L symmetry, the η w emerges as a B + L pseudo-Goldstone boson or as a Stückelberg 2-form of the electroweak gauge redundancy. An intriguing scenario of the first category is the emergence of η w in the form of the phase of a U ( 1 ) B + L -violating fermion condensate triggered by the instantons, somewhat similar to the η ′ meson in QCD. Regardless of its origin, the presence of the η w meson in the theory appears to be a matter of consistency.