# Extensive air showers as probes of hadronic interactions beyond the LHC energies

**Advisor:** Eva Santos or Jakub Vícha or Jan Ebr or Vladimír Novotný (IP CAS)

**Funding:** fully funded from grant GAČR JUNIOR STAR 21-02226M

**Contact:** esantos@fzu.cz

The study of ultra-high energy cosmic rays provides us with a unique yet challenging window to probe hadronic interactions at energies an order of magnitude greater than those at the LHC.

The properties of hadronic interactions cannot be calculated from first principles. Therefore, the required extrapolation of current man-made accelerator data to unreachable phase spaces and energies leads to significant systematic uncertainties and inconsistencies in the physics description of the characteristics of extensive air showers.

The aim of this project is to improve the current situation through a comprehensive study of extensive air shower observables using data from several cosmic ray experiments and extensive Monte Carlo simulation libraries to put constraints on the hadronic interaction models and exotic physics scenarios.

Being part of a comprehensive broad project, candidate Ph.D. students may choose among:

- Pure phenomenological studies, using public data from several cosmic-ray experiments [1, 2];
- Identifying the relevant hadronic interaction parameters leading to a coherent description of air-shower data and learning how to organize and produce extensive simulations libraries using farm and grid computing [3,4];
- Develop new analyses for current and future cosmic ray detectors [5,6].

Candidates for this project will be considered jointly with the project Ultrahigh-energy cosmic rays with AugerPrime.

References:

[1] Vícha, J., PoS ICRC2019, 452
(2019).

[2] Novotný, V., Nosek, D., Blažek, J., Astron. Nachr. 340, ed. by
K. Strassmeier et al., 234–236 (2019).

[3] Ebr, J., P. Nečesal, J. Řidky,
Astropart. Phys. 90, 37–49, arXiv: 1606.03288 (astro-ph.HE) (2017).

[4]
Blažek, J. , Vícha, J., Ebr, J., Ulrich, R., Pierog, T. and Trávníček, P.,
PoS ICRC2021, 441 (2021).

[5] Novotný, V., PoS ICRC2019, 374, arXiv:
1909.09073 (astro-ph.HE) (2019)

[6] Cazón, L. , Conceição, R., Pimenta,
M., Santos, E., Astropart. Phys. 36, 211–223, arXiv: 1201.5294 (astro-ph.HE)
(2012)