Effects of nuclear structure on parity nonconservation in atomic cesium in relativistic mean field theory

Abstract

Experiments suggested in @1# for measuring parity nonconservation ~PNC! in heavy atoms have provided an important confirmation @2,3# of the SU(2)3U(1) electroweak sector of the standard model. One can explore the possibility of new physics beyond the standard model @4# by combining the very accurate measurement of PNC in atomic cesium with sophisticated many-body calculations @5,6#. A recent measurement of parity nonconservation in atomic cesium @3# has reduced significantly the uncertainty (,1%) in the determination of the weak charge QW of the Cs nucleus @3#. The latest result @7# QW 5272.06(28)expt(34)atomic theory disagrees slightly, at the 2.5s level, with the standard model prediction of QW st . 5273.1260.06. The experimental result needs input from atomic structure calculations in the vicinity of the nucleus. However, the small but nonnegligible effects of nuclear size must be addressed before an interpretation of PNC data in terms of the fundamental electroweak couplings is possible. In particular, variations in the neutron distribution among the isotopes affect the weak charge. Thus nuclear structure could become a crucial factor in the interpretation of PNC experiments of increasing accuracy @8–11#. There have been earlier studies to determine nuclear structure effects in PNC in atomic cesium using nonrelativistic potentials @10,11#. Recently a parametric approach of nuclear effects in atomic parity nonconservation has been used @12#. In this paper we present a relativistic calculation of these effects for the first time using relativistic mean field ~RMF! theory. The RMF theory first proposed by Teller and co-workers @13,14# and Durr @15# and later by Walecka @16# and developed by others has been fairly successfully applied to both finite nuclear matter and infinite nuclei. RMF theory has the advantage that, with proper relativistic kinemetics and with the mesons and their properties already known or fixed from the properties of a small number of nuclei @17–21#, the method gives a good description for binding energies, root mean square ~rms! radii, quadrupole and hexadecapole deformations, and other nuclear properties not only spherical,