A new measurement of the strong nuclear force, which binds protons and neutrons together, confirms previous hints of an uncomfortable truth: We still don’t have a solid theoretical grasp of even the simplest nuclear systems.
To test the strong nuclear force, physicists turned to the helium-4 nucleus, which has two protons and two neutrons. When helium nuclei are excited, they grow like an inflating balloon until one of the protons pops off. Surprisingly, in a recent experiment, helium nuclei didn’t swell according to plan: They ballooned more than expected before they burst. A measurement describing that expansion, called the form factor, is twice as large as theoretical predictions.
If you want to read the actual article, it's here:
https://journals.aps.org/prl/abstract/1 ... 130.152502
There's a good chance here that Weinberg's groundbreaking 1990 paper will be superseded with a new theoretical framework.
What's the question: how does the strong nuclear force hold atoms' nuclei together?
