Production and propagation of heavy hadrons in air-shower simulators

TL;DR

This paper introduces a new module in the AIRES air-shower simulator to model the production, propagation, and decay of heavy hadrons like charm and bottom in high-energy cosmic ray interactions, enabling better analysis of their effects.

Contribution

A novel simulation module for heavy hadron production and decay in air showers, integrated into AIRES, allowing detailed study of heavy quark effects in cosmic ray physics.

Findings

Heavy hadrons can transport energy deep into the atmosphere.

Charm and bottom production rates depend on primary energy and depth.

Heavy hadron decay products influence high-energy lepton fluxes.

Abstract

Very energetic charm and bottom hadrons may be produced in the upper atmosphere when a primary cosmic ray or the leading hadron in an extensive air shower collide with a nucleon. At $E\approx 10^8$ GeV their decay length becomes of the order of 10 km, implying that they tend to interact in the air instead of decaying. Since the inelasticity in these collisions is much smaller than the one in proton and pion collisions, there could be rare events where a heavy-hadron component transports a significant amount of energy deep into the atmosphere. We have developed a module for the detailed simulation of these processes and have included it in a new version of the air shower simulator AIRES. We study the frequency, the energy distribution and the depth of charm and bottom production, as well as the depth and the energy distribution of these quarks when they decay. As an illustration, we consider the production and decay of tau leptons (from $D_s$ decays) and the lepton flux at PeV energies from a 30 EeV proton primary. The proper inclusion of charm and bottom hadrons in AIRES opens the possibility to search for air-shower observables that are sensitive to heavy quark effects.