Paper “Approaches to photon absorption in a Lorentz invariance violation scenario” (DOI: 10.1103/physrevd.110.063035) was published in Physical Review D. Filip Reščić was one of the main authors. The paper can also be found in ArXiv: 2404.07842
In this work, we performed a complete and explicit calculation of the cross section for the γ-γ scattering in LIV framework, and proposed a more appropriate approach to testing LIV on universe transparency to gamma rays. With this, we are correcting a common mistake that all previous experimental tests made, which led to underestimation of the LIV effect by up to 25 %.
The work started as a master thesis of a master student, F. I. Vrban (supervised by Tomislav Terzić), which was later turned into a research paper.
Paper abstract: Very high-energy astrophysical gamma rays suffer a suppression of their flux along their propagation due to their interaction, through the γγ→e+e− pair-production process, with the soft photon backgrounds present in the Universe. We examine the Universe’s transparency to gamma rays within a Lorentz Invariance Violation (LIV) framework, focusing on photon subluminal quadratic corrections driven by a high-energy scale. Based on an explicit calculation, we provide a new expression for the cross section that overcomes the limitations of previous approaches and refines existing constraints for the LIV scale, while we introduce a new approximation that may be useful in LIV scenarios beyond effective field theory. These improvements appear essential for setting constraints on LIV effects with future observations at ultra-high energies, where previous approximations may fall short.
