  We report the microscopic origins of the anomalously suppressed beta decay of
14C to 14N using the ab initio no-core shell model (NCSM) with the Hamiltonian
from chiral effective field theory (EFT) including three-nucleon force (3NF)
terms. The 3NF induces unexpectedly large cancellations within the p-shell
between contributions to beta decay, which reduce the traditionally large
contributions from the NN interactions by an order of magnitude, leading to the
long lifetime of 14C.

Nuclear Theory