We present new results for the phase space factors involved in double-$\beta$ decay for ${\beta }^{-}{\beta }^{-}$ transitions to ground states and excited $0_1^{+}$ states for isotopes of experimental interest. The Coulomb distortion of the electron wave functions is treated by solving numerically the Dirac equation with inclusion of the finite nuclear size and electron screening effects and using a Coulomb potential derived from a realistic proton density distribution in the daughter nucleus. Our results are compared with other results from literature, obtained in different approximations, and possible causes that can result in differences are discussed.

• Received 1 July 2013

DOI:https://doi.org/10.1103/PhysRevC.88.037303