Over the years, the discovery of dark matter—and the related particles and forces we have come to expect—has resulted in a number of false dawns. Despite our best efforts, any proof of the production of this invisible kind of matter, which is assumed to account for the vast bulk of everything in the known universe, has remained elusive.
However, in 2015, a group of Hungarian researchers proposed that they had discovered a particle dubbed X17, which most likely interacts with dark matter in some way.
The team just announced that they had additional evidence for the X17 particle in a second experiment, which will revolutionise physics as we know it. But not everyone is convinced, and fresh experimental plans are being developed to uncover the truth.
The latest discoveries are reported by Attila Krasznahorke of the Hungarian Academy of Sciences’ Institute for Nuclear Research and colleagues (ATOMKI). The scientists studied the disintegration of the beryllium-8 nucleus in 2015 and discovered that the pairs of electrons and positrons (antimatter counterparts of electrons) expelled were compatible with the additional decay of a mystery extra particle, the X17 particle.
The researchers claim to have discovered evidence for this particle again again, this time in the disintegration of a helium-4 nucleus. “We explored the disintegration of high-energy atomic states, first in beryllium-8, then in helium-4,” Krasznahorke explains. “We discovered an anomaly, a minor gap between expected and experimental results.”
To explain this disparity, we proposed a new particle that develops in the atomic nucleus and leaves as electron-positron couples. The
The Hungarian Academy of Sciences’ Institute for Nuclear Research includes hitting an object with protons to analyse its nuclear disintegration.
This methodology differs from standard particle detecting technologies, such as those used in Geneva. Near CERN, the Large Hadron Collider (LHC) smashes protons together at high energy and monitors the particles released in the collision.
The Hungarian Academy of Sciences’ Institute for Nuclear Research, on the other hand, is looking for a technique to handle unexpected particles. According to Jesse Thaler of the Massachusetts Institute of Technology’s Center for Theoretical Physics, who was not engaged in the experiment, the 17 MeV scale is “impossible to investigate using the Large Hadron Collider, which runs at very high energies.
Other scientists have attempted and failed to uncover evidence for the X17 particle since the Hungarian team released their first publication in 2015.
However, an external analysis published in 2016 claimed that if this particle exists, it might be proof of a “fifth force” of nature, namely dark matter.
“This fifth force basically suggests that there is a new particle that mediates the new interactions, or new forces,” says Daniel Alves, a particle physicist at Los Alamos National Laboratory who was not involved in the study of the Hungarian team. “It is possible that this particle is part of a bigger ‘dark sector,’ which implies that it may interact with dark matter particles. It might be a gateway to this area.”
However, an external analysis published in 2016 claimed that if this particle exists, it might be proof of a “fifth force” of nature, namely dark matter. “This fifth force basically suggests that there is a new particle that mediates the new interactions, or new forces.
” says Daniel Alves, a particle physicist at Los Alamos National Laboratory who was not involved in the study of the Hungarian team. (“It is possible that this particle is part of a bigger ‘dark sector,’ which implies that it may interact with dark matter particles. It might be a gateway to this area.”
Theoretical scientist Matt Strassler, a Harvard University theoretical physicist who was not engaged in the Hungarian team’s investigation, observes that this particle would be unstable.
However, the existence of this particle is far from definite. The fact that only the Hungarian team has been able to see it thus far has alarmed other scientists, who believe that the data may be explained by an error in the experiment’s design.
Strassler also pointed out that several unusual qualities are necessary for the particle’s stated properties. “It’s not simple to draw up mathematical calculations where you have a particle that interacts more with neutrons and electrons than protons and neutrinos.” “It only makes the tale a little more unbelievable.”
This evaluation, however, does not imply that other scientists are not seeking for X17. The NA64 collaboration at CERN tried and failed to discover the signature of the first particle.
When the LHC modifications are done in the next year or two, scientists intend to utilise the Large Hadron Collider Beauty (LHCB) experiment to analyse another particle known as the Beauty quark to see if the enigmatic X17 particle appears.
“Based on our findings, the LHCb experiment should have been able to collect enough data by 2023 to make a clear declaration regarding the X17 particle,” Thaler said.
Alves and his colleagues are also investigating the prospect of searching for the particle at Los Alamos. “We’re looking into whether what Los Alamos analyses for other purposes may be repurposed to seek for signals of this new particle,” Alves adds, noting that their technique of discovery will differ from that of the Hungarian team.
“The Hungarian team looked at two nuclear transitions,” she explains, “one in beryllium-8 and one in helium-4.” “We’ll be looking at particle generation in neutron-capture processes, which occur when one neutron is caught by another nucleus and can emit stuff in the process.” Its most typical emission is a photon, but it might potentially produce this novel X17 particle.
There is certainly doubt, but there is also a lot of enthusiasm about the prospect of an X17 particle. It may take years before we know for certain whether it exists, but if it does, it will open up an altogether new area of physics and a window into the unknown. “Of course,” Krasznahorkay responds, “I think it exists.” “However, I have some harsh detractors.”