Astrophysicists have proposed a new solution to the "muon mystery."

The discovery of cosmic rays — a significant milestone in the history of science — occurred shortly after the detection of X-rays and radioactivity (at the end of the 19th to the beginning of the 20th century). One of their primary sources within the Milky Way is the explosions of supernovae: the cores of various elements of cosmic rays (charged particles) are formed in these bursts and accelerated on shock waves. Naturally, there are more cosmic rays in the metagalaxy.

When charged particles, such as protons and nuclei of heavy elements, reach the Earth's atmosphere and interact with the nuclei of atmospheric gases, they produce pions (secondary particles), which then decay into muons. Scientists refer to this process as a extensive air shower. It seems straightforward, yet existing theoretical models do not explain the excess of muons on the Earth's surface. It is worth noting that muons are particles similar to electrons with the same spin and charge, but with a much greater mass (207 times). Astrophysicists still struggle to solve this puzzle.

Nevertheless, a research group led by Bingyang Liu, Zhixiang Yang, and Jianhong Ruan from East China Normal University (China) has presented a fresh perspective on the issue through a gluon condensation model developed using AIRES software and based on fundamental principles of quantum chromodynamics (which describes the interaction of quarks and gluons). The findings of their work are published in the journal The Astrophysical Journal.

Gluons are particles that mediate the strong interaction between quarks in atomic nuclei. Under conditions of ultra-high energies (the initial stage of cosmic ray collisions with the Earth's atmosphere), the distribution of these particles can change. The gluon condensation model presented by the team of scientists suggests that gluons condense at certain energies, leading to their high density at a critical momentum.

Specifically, particle collision modeling resulted in an increase in the number of strange quarks, which was immediately followed by a rise in the number of kaons — the lightest particles formed from a strange quark (or anti-strange quark) and an up or down quark. Unlike pions, kaons decay less frequently into photons, but more often into muons and neutrinos. This process retains more energy and results in the excessive production of muons.

Thus, the gluon condensation model explains the observed number of muons and, importantly, does not contradict other significant parameters, such as the depth of the extensive air shower maximum (Xmax, an area and stage of shower development characterized by the highest number of particles) — the latter aligns with experimental data.

The team also considered various scenarios for energy distribution between protons and secondary particles and found that under certain conditions, the results match experimental data.

If further observations confirm the conclusions reached by the authors of the scientific work, the current understanding of particle interactions under extreme conditions will change and significantly impact the interpretation of data not only in astrophysics but also in experiments at particle accelerators such as the Large Hadron Collider.

It is important to note that the results proposed by the research group represent a significant step in solving the "muon puzzle," opening up opportunities for further research and possible revisions of existing particle interaction models.