New Experiment Challenges Nucleus Theory

An experiment conducted by Simon Kegel and his colleagues has cast doubt on the leading theory of the nucleus. The experiment involved exciting helium nuclei by shooting a beam of electrons at a tank of cold helium gas. The team then compared the change in the nucleus's spread with a variety of theoretical calculations, but none of the theories matched the data. The calculation that came closest used an oversimplified model of the nuclear force, not the chiral effective field theory. Several groups plan to repeat the calculations to find out what went wrong.