Four fundamental forces, namely gravitation, electromagnetism, strong nuclear forces and weak nuclear forces, are currently accepted in the study of physics. Without these fundamental forces, all matter in the universe would fall apart. A new study, however, suggests that there may be a fifth force of nature.

Jonathan Feng, from the University of California, Irvine, and colleagues conducted an analysis of data that were gathered by researchers from the Hungarian Academy of Sciences during a research on the so-called dark photons.

The mid-2015 study detected evidence of the previously unknown subatomic particle 30 times heavier than electron. Dark photon, the hypothetical elementary particle, is proposed as an electromagnetic force carrier for dark matter, which comprises 85 percent of the mass of the universe. It was first proposed in 2008.

The Hungarian physicists' study merely indicated the discovery of a new particle, but findings of the new study by Feng and colleagues suggest that it was not dark photon that was discovered but a protophobic X boson. The existence of this particle could be an indication of a fifth force of nature.

Electromagnetic forces act on both protons and electrons, but the newly found particle appears to only interact with electrons and neutrons at short distances. The possible fifth force, according to Feng, may also be linked to electromagnetic force, as well as strong and weak nuclear forces embodying one grander and more fundamental force.

A separate sphere of physics, a dark sector in contrast to the standard model with dark matter and dark forces, is also possible. The researchers said that these two sectors may interact with each other through fundamental but veiled interactions.

"This dark sector force may manifest itself as this protophobic force we're seeing as a result of the Hungarian experiment," Feng said, adding that this fits in with their original research that aimed to shed light on the nature of dark matter.

The researchers, however, said that the interpretations still require further studies.

"We present anomaly-free extensions of the Standard Model that contain protophobic gauge bosons with the desired couplings to explain the 8Be anomaly," the researchers wrote in their study, which is published in the Physical Review Letters.

"The models predict relatively large charged lepton couplings ~ 0.001 that can resolve the discrepancy in the muon anomalous magnetic moment and are amenable to many experimental probes. The models also contain vectorlike leptons at the weak scale that may be accessible to near future LHC searches."

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