A theoretical study by RIKEN physicists, published in Physics Letters B, has accurately determined the interaction between a charmonium and a proton or neutron for the first time.

From two galaxies colliding to an electron jettisoned from a nucleus, all interactions in the universe can be described in terms of just four fundamental forces.

Gravity and the electromagnetic force are the two we are familiar with in everyday life, while the weak and strong forces operate over minuscule distances—roughly the size of an atomic nucleus or smaller.