Testing Hadronic Interactions at Ultrahigh Energies with Air Showers Measured by the Pierre Auger Observatory

• Published in: Physical review letters Vol. 117; no. 19; p. 192001
• Main Authors: Aab, A, Abreu, P, Aglietta, M, Ahn, E J, Al Samarai, I, Albuquerque, I F M, Allekotte, I, Allen, J D, Allison, P, Almela, A, Alvarez Castillo, J, Alvarez-Muñiz, J, Ambrosio, M, Anastasi, G A, Anchordoqui, L, Andrada, B, Andringa, S, Aramo, C, Arqueros, F, Arsene, N, Asorey, H, Assis, P, Aublin, J, Avila, G, Badescu, A M, Baus, C, Beatty, J J, Becker, K H, Bellido, J A, Berat, C, Bertaina, M E, Bertou, X, Biermann, P L, Billoir, P, Biteau, J, Blaess, S G, Blanco, A, Blazek, J, Bleve, C, Blümer, H, Boháčová, M, Boncioli, D, Bonifazi, C, Borodai, N, Botti, A M, Brack, J, Brancus, I, Bretz, T, Bridgeman, A, Briechle, F L, Buchholz, P, Bueno, A, Buitink, S, Buscemi, M, Caballero-Mora, K S, Caccianiga, B, Caccianiga, L, Cancio, A, Canfora, F, Caramete, L, Caruso, R, Castellina, A, Cataldi, G, Cazon, L, Cester, R, Chavez, A G, Chiavassa, A, Chinellato, J A, Chirinos Diaz, J C, Chudoba, J, Clay, R W, Colalillo, R, Coleman, A, Collica, L, Coluccia, M R, Conceição, R, Contreras, F, Cooper, M J, Coutu, S, Covault, C E, Cronin, J, Dallier, R, D'Amico, S, Daniel, B, Dasso, S, Daumiller, K, Dawson, B R, de Almeida, R M, de Jong, S J, De Mauro, G, de Mello Neto, J R T, De Mitri, I, de Oliveira, J, de Souza, V, Debatin, J, Del Peral, L, Deligny, O, Dhital, N, Di Giulio, C, Di Matteo, A
• Format: Journal Article
• Language: English
• Published: United States 04.11.2016
• ISSN: 1079-7114
• DOI: 10.1103/PhysRevLett.117.192001

Ultrahigh energy cosmic ray air showers probe particle physics at energies beyond the reach of accelerators. Here we introduce a new method to test hadronic interaction models without relying on the absolute energy calibration, and apply it to events with primary energy 6-16 EeV (E_{CM}=110-170  TeV), whose longitudinal development and lateral distribution were simultaneously measured by the Pierre Auger Observatory. The average hadronic shower is 1.33±0.16 (1.61±0.21) times larger than predicted using the leading LHC-tuned models EPOS-LHC (QGSJetII-04), with a corresponding excess of muons.