Electroweak Axion in Light of GRB221009A

Very high energy (VHE) photons may have a higher survival rate than that expected in standard-model physics, as suggested by the recently reported gamma ray burst GRB221009A. While a photon-axion like particle (ALP) oscillation can boost the survival rate of the VHE photons, current works have not been based on concrete particle models, leaving the identity of the corresponding ALP unclear. Here, we show that the required ALP scenario is consistent with the electroweak axion with an anomaly free Z₁₀ Froggatt–Nielsen symmetry.