The mystery of coplanarity of most powerful energy flows in EAS cores

Abstract High-altitude and stratospheric experiments with X-ray emulsion chambers have revealed a tendency for coplanar arrival of the most energetic particles and/or narrow subcascades in cores of extensive air showers. Simulations of the cascade development in the atmosphere based on traditional models of hadron interactions, namely, FANSY 2.0/QGSJ, QGSJET II-04 and SIBYLL 2.3E, have been carried out. In addition, the FANSY 2.0/2D model based on the hypothesis of a connection between coplanarity and local 3D $$\rightleftarrows $$ ⇄ 2D evolution of the metric signature at superhigh energies is also used. This model reproduces the coplanar generation of the most energetic particles at hadron interactions at superhigh energies. Simulation results are compared with experimental data. It is concluded that the totality of experimental data on the above-mentioned effect, observed at depths of 15, 100, and 600 g/cm $$^2$$ 2 in the atmosphere, cannot be explained even within the framework of the FANSY 2.0/2D model.