Theoretical Physicists Confirm Possible Discovery of Nature’s Fifth Fundamental Force

Recent findings by a team of experimental nuclear physicists in Hungary indicating the possible discovery of a new subatomic particle may be evidence of a fifth force of nature, according to a team of theoretical physicists at the University of California, Irvine.

The discovery of a possible fifth force of nature would completely change our understanding of the Universe, according to Jonathan L. Feng et al. This Hubble image shows the Whirlpool Galaxy (also known as Messier 51 and NGC 5194) and its companion galaxy, NGC 5195. Image credit: NASA / ESA / S. Beckwith, STScI / Hubble Heritage Team / STScI / AURA.

“If true, it’s revolutionary. For decades, we’ve known of four fundamental forces: gravitation, electromagnetism, and the strong and weak nuclear forces,” said Prof. Jonathan Feng, professor of physics astronomy in the Department of Physics and Astronomy at the University of California, Irvine.

“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 team came upon a recent study by Dr. Attila Krasznahorkay from the Hungarian Academy of Sciences’ Institute for Nuclear Research in Debrecen, Hungary, and co-authors (arXiv.org preprint) who were searching for ‘dark photons,’ particles that would signify unseen dark matter, which physicists say makes up about 85% of the Universe’s mass.

The work by A. Krasznahorkay et al uncovered a radioactive decay anomaly that points to the existence of a light particle just 30 times heavier than an electron.

“The experimentalists weren’t able to claim that it was a new force. 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,” Prof. Feng said.

Prof. Feng and his colleagues studied the Hungarian team’s data as well as all other previous experiments in this area and showed that the evidence strongly disfavors both matter particles and dark photons.

They proposed a new theory, however, that synthesizes all existing data and determined that the discovery could indicate a fifth force.

Their initial analysis was published on April 25 on the arXiv.org preprint server, and this month in the journal Physical Review Letters. A follow-up paper amplifying the conclusions of the first work was released August 11 on arXiv.org.

The analysis demonstrates that instead of being a dark photon, the particle may be a ‘protophobic X boson.’

While the normal electric force acts on electrons and protons, this newfound particle interacts only with electrons and neutrons – and at an extremely limited range.

“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,” said co-author Prof. Timothy Tait.

“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,” Prof. Feng added.

“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.”

Like many scientific breakthroughs, this one opens entirely new fields of inquiry.

One direction that intrigues scientists is the possibility that this potential fifth force might be joined to the electromagnetic and strong and weak nuclear forces as manifestations of one grander, more fundamental force.”

Citing physicists’ understanding of the standard model, Prof. 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,” Prof. Feng 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.”

_____

Jonathan L. Feng et al. 2016. Protophobic Fifth-Force Interpretation of the Observed Anomaly in ⁸Be Nuclear Transitions. Phys. Rev. Lett. 117 (7): 071803; doi: 10.1103/PhysRevLett.117.071803

Jonathan L. Feng et al. 2016. Particle Physics Models for the 17 MeV Anomaly in Beryllium Nuclear Decays. arXiv: 1608.03591

A.?J. Krasznahorkay et al. 2016. Observation of Anomalous Internal Pair Creation in ⁸Be: A Possible Indication of a Light, Neutral Boson. Phys. Rev. Lett. 116 (4): 042501; doi: 10.1103/PhysRevLett.116.042501