Strong constraints on Lorentz violation using new γ-ray observations around PeV

The tiny modification of dispersion relation induced by Lorentz violation (LV) is an essential topic in quantum gravity (QG) theories, which can be magnified into significant effects when dealing with astrophysical observations at high energies and long propagation distances. LV would lead to photon decay at high energies; therefore, observations of high-energy photons could constrain LV or even QG theories. The Large High Altitude Air Shower Observatory (LHAASO) is the most sensitive gamma-array instrument currently operating above 100 TeV. Recently, LHAASO reported the detection of 12 sources above 100 TeV with maximum photon energy exceeding 1 PeV. According to these observations, the most stringent restriction is achieved in this study, i.e., limiting the LV energy scale to $1.7\times10^{33} $ eV, which is over 139,000 times that of the Planck energy, and achieving an improvement of approximately 1.9 orders of magnitude over previous limits. * Supported in China by National Key R&D program of China (2018YFA0404201) and National Science Foundation of China (NSFC) (12022502)