Everything in our Universe is held together or moves due to four types of fundamental forces – the forces of gravity, electromagnetism, strong and weak nuclear interactions. But physicists have long had suspicions about the existence of the fifth kind of fundamental force, supported by evidence and justified by calculations. And recently, scientists from the Hungarian Institute for Nuclear Research have received additional and reliable evidence using helium atoms.
Note that the same team of researchers has already received evidence of the existence of the fifth force in 2016 during observations of the decay of beryllium-8 atoms. Then scientists put forward the assumption that the mysterious particle, called X17, is the carrier of this force. During the experiments, scientists observed the light generated by an excited beryllium atom at the moment before its decay. If the energy of the photon of light is large, it immediately turns into an electron and a positron, flying at an angle, the value of which is determined by the initial energy of the photon, according to the law of conservation of energy.
But during the experiment, scientists saw something strange, a sufficiently large number of electrons and positrons scattered at an “impossible” angle of 140 degrees. The collected data and the results of their research have allowed scientists to conclude that a completely unknown particle, which may be a new kind of fundamental boson particles, is responsible for the observed anomaly.
This assumption has a solid foundation. Three types of fundamental forces have corresponding carrier particles from the form of bosons. And the forces of gravity are provided by a hypothetical particle – a graviton, a particle that has not yet been detected. The new boson particle is not related to other bosons, carriers of fundamental forces, primarily because of its mass, which is 17 MeV, which makes it 33 times heavier than an electron, and a tiny period of life that is 10^-14 seconds.
To confirm the results obtained in 2016, Hungarian scientists conducted other experiments for four years. And one of the last experiments, in which the state of the excited helium atom was monitored, brought positive results. As in the first experiment, scientists discovered pairs of electrons and positrons flying at an angle of 115 degrees “impossible” for helium. Calculations based on the collected experimental data have shown that a boson particle with an energy of slightly less than 17 MeV may be to blame for this, which is in good agreement with the results of the first studies. And, thanks to an energy of 17 MeV, the new boson is called X17.
If the boson X17 is not an illusion or the result of experimental error, then it interacts with neutrons and other subatomic particles in a completely different way than the other four fundamental forces do. And, it is likely that this particular particle is directly related to dark matter, one of the biggest mysteries of modern physics.
It is quite natural that recognition of the X17 boson as an officially found particle will require a lot of efforts and experiments conducted by various independent groups of scientists in various fields of nuclear physics. And if the boson X17, in the end, receives the status of an official particle, this will require a revision and restructuring of the entire Standard Model of particle physics in order for a new member and the fundamental force that it carries to find an appropriate place there.