
"protophobic X boson"
..."The potential fifth force may be linked to the electromagnetic and strong and weak nuclear forces, as "manifestations of one grander, more fundamental force," Feng said."...
..."this newfound particle apparently interacts only with protons and neutrons, and then only at very short distances, researchers said."...
It's clear that when we are approaching an unknown force, any and all possibilities must be considered...In fact all four forces of nature could turn out to be manifestations of one fundamental force....
Article link...
http://www.space.com/33750-fifth-force-of-nature-dark-matter.html