Speaker
Description
The lifetime of free neutrons was a long-standing puzzle: in the beam experiments it significantly exceeded the corresponding result from the trap experiments – far beyond the error margins. While the results of the trap experiments were based on counting neutrons, the results of the beam experiments were based on counting protons stemming from the 3-body decay of a neutron into a free proton and a free electron (plus antineutrino). It was well-known that there is a relatively small probability for the 2-body decay of a free neutron into a hydrogen atom (plus antineutrino). For explaining the above puzzle, the Branching Ratio (BR) for this 2-body decay (missed in the beam experiments) – compared to the usual 3-body decay – should have been ~ 1%. However, the theoretical BR for such 2-body decay was previously known to be 4x10-6. In our paper in New Astronomy 113 (2024) 102275, it was pointed out that after taking into account the second solution of the Dirac equation for hydrogen atoms (that becomes legitimate for the S-states after allowing for the experimental charge distribution inside protons), the theoretical BR for the 2-body decay of free neutrons (into hydrogen atoms and antineutrinos) got enhanced by a factor ~ 3000 to become ~ 1%. The existence of such atoms (abbreviated SFHA) is evidenced by several different types of atomic experiments and by astrophysical observation; due to the quantum selection rules for the S-states, they do not interact with the electromagnetic radiation: they remain dark. Thus, the neutron lifetime puzzle appeared solved completely. In our paper in Nuclear Phys. B 1014 (2025) 116879, we proposed conceptual designs of the experiments that will constitute both the first experimental detection of the two-body decay of free neutrons and the experimental confirmation that the two-body decay of free neutrons produces overwhelmingly the SFHA. Such experiments are in preparation at Los Alamos National Lab (USA) and at Forschungszentrum Jülich (Germany). In one of the above papers, we showed that via the enhanced 2-body decay of neutrons, old neutron stars could very slowly generate the new specific, described in detail baryonic Dark Matter (DM) in the form of the SFHA. Some old neutron stars would release it into their tiny atmospheres, while some other old neutron stars would release it into the interstellar medium. Besides, mergers of a neutron star with another neutron star or with a black hole, accompanied by the ejection of neutron-rich material, can also lead to the formation of SFHA as the ejecta cools down. This is another interesting aspect of the multi-messenger astronomy focused on studying these mergers through the gravitational waves they generate. There is observational evidence of the continuing generation of new baryonic DM by neutron stars via the enhanced 2-body decay of neutrons.