Physicists at the Institute for Nuclear Research in Debrecen, Hungary, say this apparatus — an electron-positron spectrometer — has found evidence for a new particle.
Recent findings indicating the possible discovery of a previously unknown subatomic particle may be evidence of a fifth fundamental force of nature. “If true, it’s revolutionary,” said Prof. Jonathan Feng. “For decades, we’ve known of 4 fundamental forces: gravitation, electromagnetism, and the strong and weak nuclear forces. If confirmed by further experiments, this discovery of a possible fifth force would completely change our understanding of the universe, with consequences for the unification of forces and dark matter.”
The UCI researchers came upon a mid-2015 study by experimental nuclear physicists at the Hungarian Academy of Sciences who were searching for “dark photons,” particles that would signify unseen dark matter. The Hungarians’ work uncovered a radioactive decay anomaly that points to the existence of a light particle just 30X heavier than an electron. “The experimentalists weren’t able to claim that it was a new force,” Feng said. “They simply saw an excess of events that indicated a new particle, but it was not clear to them whether it was a matter particle or a force-carrying particle.”
UCI group studied the Hungarian researchers’ data as well as all other previous experiments and showed evidence strongly disfavors both matter particles and dark photons. They proposed a new theory, however, that synthesizes all existing data and determined the discovery could indicate a 5th fundamental force.
Instead of being a dark photon, the particle may be a “protophobic X boson.” While normal electric force acts on electrons and protons, this newfound boson interacts only with electrons and neutrons – and at an extremely limited range. Prof. Timothy Tait, said, “There’s no other boson that we’ve observed that has this same characteristic. Sometimes we also just call it the ‘X boson,’ where ‘X’ means unknown.”
Astronomers have examined dark matter in the galaxy cluster Abell 3827, by observing how its mass warps light coming from a more distant galaxy behind. The image hints that in one region, dark matter is not moving with the galaxy itself, possibly implying unknown interactions between dark matter clumps.
Feng noted that further experiments are crucial. “The particle is not very heavy, and laboratories have had the energies required to make it since the ’50s and ’60s,” he said. “But the reason it’s been hard to find is that its interactions are very feeble. That said, because the new particle is so light, there are many experimental groups working in small labs around the world that can follow up the initial claims, now that they know where to look.”
One direction that intrigues Feng is the possibility that this fifth force might be joined to the electromagnetic and strong and weak nuclear forces as “manifestations of one grander, more fundamental force.” Feng speculated that there may also be a separate dark sector with its own matter and forces. “It’s possible that these two sectors talk to each other and interact with one another through somewhat veiled but fundamental interactions,” he said. “This dark sector force may manifest itself as this protophobic force we’re seeing as a result of the Hungarian experiment. In a broader sense, it fits in with our original research to understand the nature of dark matter.” https://news.uci.edu/research/uci-physicists-confirm-possible-discovery-of-fifth-force-of-nature/
http://arxiv.org/abs/1608.03591
http://www.nature.com/news/has-a-hungarian-physics-lab-found-a-fifth-force-of-nature-1.19957
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