Implications of gamma-ray photon measurements at the LHAASO on Lorentz symmetry

The Large High Altitude Air Shower Observatory(LHAASO)has reported the measurement of photons with high energies of up to 1.42 PeV from twelve gamma-ray sources.We are concerned with the implications of the LHAASO data on the fate of Lorenz symmetry at such high energy levels;thus,we consider the interaction between gamma rays and photons in the cosmic microwave background(CMB)and compute the optical depth,mean free path,and survival probability of photons from these gamma-ray sources.Employing the threshold value predicted by standard special relativity,the lowest survival probability for observed gamma ray photons is found to be approximately 0.60,which is fairly high and implies that abundant photons with energies above the threshold may reach the Earth without Lorentz symmetry violation.We conclude that it is unreasonable to argue that Lorentz symmetry would be violated using current observations at the LHAASO.