Test of Lorentz invariance through observation of the maximum depths in giant air showers

• Published in: Nuclear physics. Section B, Proceedings supplement Proceedings supplement, 2003-07, Vol.122, p.321-324
• Main Authors: Dedenko, L.G., Fedorova, G.F., Fedunin, E.Yu, Kirillov, A.A., Roganova, T.M.
• Format: Article
• Language: English
• ISSN: 0920-5632; 1873-3832
• DOI: 10.1016/S0920-5632(03)80409-7

An idea that exact Lorentz invariance can be violated was proposed by Coleman and Glashow to overcome the astrophysical problems with giant air showers. In view of this idea neutral pions do not decay at high energies, resulting in a faster shower development. As a consequence, the depth, X max , of shower maximum decreases, but on the contrary the muon maximum production height becomes larger. This characteristic behavior of the shower maximum depth and the muon production height may be used as the specific signature of models with tiny departures from exact Lorentz invariance. The longitudinal development of showers and the distribution of X max are calculated in terms of the quark-gluon string model with allowance made for the Landau-Pomeranchuk-Migdal effect and interactions of ultrahigh energy neutral pions with atomic nuclei in the atmosphere. Comparison of calculations with available experimental data provides a new limit < 10 −22 for the difference of maximal attainable velocities of photons and neutral pions. The suggestion that ultrahigh energy primary cosmic rays may include neutral pions is also discussed.