Impact of the Center of Mass Fluctuations on the Ground State Properties of Nuclei

Abstract: Ground state properties across the entire nuclear chart are described predominantly and very accurately within the density functional theory (DFT). DFT however breaks many symmetries, among them the most important being the translational, rotational and gauge symmetries. The translational symmetry breaking is special, since it is broken for all nuclei, unlike the rotational and gauge symmetries. Here we analyze the center-of-mass (CoM) projection method suggested by \textcite{Peierls:1957} in 1957, which leads to a many-body wave function consistent with intrinsic translational symmetry, a procedure similar in spirit to those suggested for restoring rotational and gauge symmetries. The magnitude of the CoM correction to the binding energies of nuclei varies between 10 and 7 MeV from light to heavy nuclei, which is significantly larger than the RMS energy error in the Bethe-Weizs\"acker mass formula, which is about 3.5 MeV. The CoM energy correction is also larger than the RMS energy deviation achieved in any DFT mass evaluations of the nuclear masses performed so far (without any symmetry restoration or zero-point energy fluctuations), with an energy RMS typically between 2 and 3 MeV. Since energy density functionals are used in many dynamical simulations, albeit so far without symmetry restoration, and also in nuclear structure calculations, it is crucial the improve the quality of the presently used energy density functions by accounting in an uniform manner for the CoM fluctuations.