Enhanced sensitivity to variation of fundamental constants in the transitions of²²⁹Th and²⁴⁹Bk

Abstract

The transition frequencies between the first excited state and the ground state in 229Th and 249Bk may exhibit enhanced sensitivity to the temporal variation of some fundamental physical constants compared with that of the current typical atomic clocks. Our results demonstrate that the sensitivity of the transition frequency to the relative variation of the dimensionless strong interaction parameter mq/ΛQCD is enhanced by about 5 orders of magnitude in 229Th and 2 orders in 249Bk. The sensitivity of the transition frequency to the relative variation of fine structure constant α is different from proton to neutron. The enhancement of the sensitivity to α variation is about 2 orders of magnitude larger for a proton-excited state than that for a neutron one. The sensitivity to α variation is enhanced by 3 orders of magnitude for the 3.5 eV neutron-excited state in 229Th while it is enhanced by 2 orders of magnitude for the 8.78 keV proton-excited state in 249Bk.