Experiments that measure the lifetime of neutrons reveal a perplexing and unresolved discrepancy. While this lifetime has been measured to a precision within 1 percent using different techniques, apparent conflicts in the measurements offer the exciting possibility of learning about as-yet undiscovered physics.
Now, a team led by scientists in the Nuclear Science Division at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) has enlisted powerful supercomputers to calculate a quantity known as the “nucleon axial coupling,” or gA—which is central to our understanding of a neutron’s lifetime—with an unprecedented precision. Their method offers a clear path to further improvements that may help to resolve the experimental discrepancy.
Illinois Physics alumnus Chia Cheng “Jason” Chang is lead author on the paper. Chang received his bachelor’s degree in 2008 and his doctoral degree in 2015, both from the Department of Physics at the University of Illinois at Urbana-Chmpaign. Chang’s doctoral adviser at Illinois was Professor Aida El-Khadra. These results were achieved while Chang was a postdoctoral researcher in Berkeley Lab’s Nuclear Science Division. Chang currently holds an appointment as a research scientist at the Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS) of the Institute of Physical and Chemical Research (RIKEN), Japan.