A new string model for hadron and muon production in extensive air showers

Quark-gluon string fragmentation is usually seen as a scalable process independent of the type of colliding system. Existing experimental data from both collider-based and cosmic-ray experiments suggest the need to break this universality. While some improvements can be achieved by including the collective effects, a free string fragmentation is still of interest. In this paper I present the first results of multi-particle production simulations using the ATROPOS quark-gluon string fragmentation model. ATROPOS is founded on the strict first principles of the Nambu-Goto theory with relativistic string being defined by a mathematically derived method based on the Virasoro conditions. To differentiate between various colliding systems, ATROPOS allows consideration of the angular momentum of quark-gluon string that affects particle production. The natural introduction of non-universality in hadronization process is demonstrated. A preliminary estimate of the impact on hadron (and muon) production in extensive air showers is presented.