“Probing the core of the strong nuclear interaction” published in Nature

My latest research article, “Probing the core of the strong nuclear interaction” has been published in the February 26th issue of the journal, Nature. The article describes a study of the force between protons and neutrons (collectively called “nucleons”) at very short distance scales, that is, less than a femtometer or 10^-15 m. Nuclear forces have traditionally been studied by shooting one accelerated nucleon at another, and looking at the distributions of scattering angles as a function of momentum. To study forces at shorter distance scales, one needs to shoot nucleons with higher and higher momenta. At very short-distance scales, this technique becomes unwieldy, not because we can’t build particle accelerators of sufficient size, but because the collisions start producing copious amounts of other particles, complicating the interpretation in terms of nuclear forces. In this paper, my collaborators and I show how a new approach can work. Nucleons inside the nucleus are constantly moving around, and at any given moment, some will find themselves a very short-distance away from a partner nucleon. By using high-energy electron scattering, we can knock this “short-range correlated pair” out of the nucleus and study it. In doing so, we found clear evidence of a transition to a “repulsive core” at extremely short distances! This can have big implications for the structure of the cores of neutron stars, in which neutrons are packed at even higher density than inside a nucleus.

If you’re interested to learn more, I invite you to read the excellent “News and Views” companion piece by Prof. Alexandra Gade of Michigan State.