Experiment Hints at Fifth Force of Nature

The Standard Model, physics' most reliable theory for classifying and mapping the interactions between subatomic particles, has four fundamental forces. They are gravity, weak force, electromagnetic force, and the strong force. Now researchers are suggesting their may be a fifth force as of yet undetected. Here is the article:

Possible case for fifth force of nature

A team of physicists at the University of California has uploaded a paper to the arXiv preprint server in which they suggest that work done by a team in Hungary last year might have revealed the existence of a fifth force of nature. Their paper has, quite naturally, caused quite a stir in the physics community as several groups have set a goal of reproducing the experiments conducted by the team at the Hungarian Academy of Science's Institute for Nuclear Research.

The work done by the Hungarian team, led by Attila Krasznahorkay, examined the possible existence of dark photons-the analog of conventional photons but that work with dark matter. They shot protons at lithium-7 samples creating beryllium-8 nuclei, which, as it decayed, emitted pairs of electrons and positrons. Surprisingly, as they monitored the emitted pairs, instead of a consistent drop-off, there was a slight bump, which the researchers attributed to the creation of an unknown particle with a mass of approximately 17 MeV. The team uploaded their results to the arXiv server, and their paper was later published by Physical Review Letters. It attracted very little attention until the team at UoC uploaded their own paper suggesting that the new particle found by the Hungarian team was not a dark photon, but was instead possibly a protophobic X boson, which they further suggested might carry a super-short force which acts over just the width of an atomic nucleus-which would mean that it is a force that is not one of the four described as the fundamental forces that underlie modern physics.

Read more at: http://phys.org/news/2016-05-case-nature.html#jCp