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arXiv · 2407.18318

Photon-likeness of hadron showers and impact of Lorentz boosting

Jannis Pawlowsky·Karl-Heinz Kampert·Julian Rautenberg
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Abstract

We examine the probability of proton-induced air showers at $E>10\,$EeV being misidentified as photon-induced due to neutral pions receiving a major part of the primary energy in the first interaction, thereby enhancing the electromagnetic shower component by their $π^0 \to γγ$ decay. Using CORSIKA simulations, we demonstrate the relevance of this effect at EeV energies. However, the probability for such photon-like events drops down strongly at the highest energies due to the increasing probability of Lorentz boosted $π^0$'s suffering hadronic interactions before decay. Different hadronic interaction models suggest that photon-like hadronic events may be observed at current UHECR observatories. A quantitative comparison of the observed number of background events found in recent photon searches published by the Pierre Auger Collaboration allows us conclude that the hypothesis of upwards fluctuations of $π^0$-production alone is insufficient to explain the data.

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Jannis Pawlowsky, Karl-Heinz Kampert, Julian Rautenberg. 2025-03-12. Photon-likeness of hadron showers and impact of Lorentz boosting. https://doi.org/10.3847/1538-4357%2Fadbe72

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