Effective field theory combines with measurements of light- to medium-mass nuclei to resolve a 50-year-old puzzle.
When measuring ß decay in medium and heavy nuclei, physicists have had to adjust, or quench, the calculated rate to match the observed rate by a factor of 0.75. Peter Gysbers (TRIUMF, Canada’s particle accelerator center), Gaute Hagen (Oak Ridge National Laboratory), and their colleagues have now developed an explanation for the mismatch between theory and observation that has puzzled nuclear physicists for the past half century. The researchers combined effective field theory and quantum many-body methods to calculate ß-decay rates in different-sized nuclei. Comparing those calculations with measured rates led the researchers to conclude that the discrepancy arises from powerful particle interactions in the nucleus. Read more.