Limits to Gauge Coupling in the Dark Sector Set by the Nonobservation of Instanton-Induced Decay of Super-Heavy Dark Matter in the Pierre Auger Observatory Data
P. Abreu, M. Aglietta, Justin M. Albury, I. Allekotte, Kévin Almeida Cheminant, A. Almela, Roberto Aloisio, Jaime Álvarez-Muñiz, Rafael Alves Batista, Juan Ammerman Yebra, Gioacchino Alex Anastasi, L. Anchordoqui, Belén Andrada, S. Andringa, C. Aramo, P. R. Araújo Ferreira, Enrico Arnone, Juan Carlos Arteaga Velázquez, H. Asorey, P. Assis, Gualberto Avila, Emanuele Avocone, Alina Mihaela Badescu, Alena Bakalová, A. Balaceanu, Felicia Barbato, J. A. Bellido, Corinne Bérat, M. E. Bertaina, Gopal Bhatta, P. L. Biermann, Virginia Binet, Kathrin Bismark, Teresa Bister, Jonathan Biteau, Jiří Blažek, C. Bleve, J. Blümer, M. Boháčová, Denise Boncioli, C. Bonifazi, Luan Bonneau Arbeletche, Nataliia Borodai, Ana Martina Botti, J. Brack, T. Bretz, P. Gabriel Brichetto Orchera, F. L. Briechle, P. Buchholz, A. Bueno, S. Buitink, Mario Buscemi, Max Büsken, K. S. Caballero‐Mora, L. Caccianiga, Fabrizia Canfora, Ioana Caracas, R. Caruso, A. Castellina, F. Catalani, G. Cataldi, Lorenzo Cazon, M. Cerda, J. A. Chinellato, J. Chudoba, L. Chytka, R. W. Clay, Agustín Cobos Cerutti, R. Colalillo, Alan Coleman, M. R. Coluccia, R. Conceição, A. Condorelli, G. Consolati, F. Contreras, Fabio Convenga, Diego Correia dos Santos, C. E. Covault, S. Dasso, K. Daumiller, B. R. Dawson, J. A. Day, Rogério Miranda de Almeida, J. de Jesús, S. J. de Jong, J. R. T. de Mello Neto, I. De Mitri, J. de Oliveira, Danelise de Oliveira Franco, F. de Palma, V. de Souza, Emanuele De Vito, Antonino Del Popolo, M. del Río, Olivier Deligny, L. Deval, Armando di Matteo, M. Dobre, C. Dobrigkeit, J. C. D’Olivo
Abstract
Instantons, which are nonperturbative solutions to Yang-Mills equations, provide a signal for the occurrence of quantum tunneling between distinct classes of vacua. They can give rise to decays of particles otherwise forbidden. Using data collected at the Pierre Auger Observatory, we search for signatures of such instanton-induced processes that would be suggestive of super-heavy particles decaying in the Galactic halo. These particles could have been produced during the post-inflationary epoch and match the relic abundance of dark matter inferred today. The nonobservation of the signatures searched for allows us to derive a bound on the reduced coupling constant of gauge interactions in the dark sector: α_{X}≲0.09, for 10^{9}≲M_{X}/GeV<10^{19}. Conversely, we obtain that, for instance, a reduced coupling constant α_{X}=0.09 excludes masses M_{X}≳3×10^{13} GeV. In the context of dark matter production from gravitational interactions alone, we illustrate how these bounds are complementary to those obtained on the Hubble rate at the end of inflation from the nonobservation of tensor modes in the cosmological microwave background.