Shell Model Estimate of Nuclear Electric Dipole Moments

Abstract

Nuclear electric dipole moments (EDMs) and Schiff moments for the lowest 1/2 + states around the mass 130 are calculated in terms of the nuclear shell model. We estimate the upper limits of the nuclear EDMs, which may be directly measured through ionic atoms. The nuclear EDM of each nucleus is slightly quenched from its single-particle estimate due to many-body effects. We also estimate the upper limit for the EDM of neutral 129 Xe atom using the Schiff moment. Subject Index: 203The standard model in particle physics violates time reversal (T ) invariance, but only through a single phase in the Kobayashi-Maskawa matrix that mixes quark flavors. 1) The resulting T violation is therefore very weak, and static electric dipole moments (EDMs) of nucleons, electrons, or atoms are predicted to be too small to be observed. 2) For the neutron EDM, |d n | < 2.9 × 10 −26 e cm was measured by Baker et al. 3) Some of the tightest constraints on T violation come from atomic EDM experiments. In 129 Xe, 199 Hg, and other atoms, EDMs were measured. Rosenberry et al. measured the upper limit d 129 Xe < 4.1 × 10 −27 e cm, 4) and Griffith et al. measured d 199 Hg < 3.1 × 10 −29 e cm. 5) The upper limits of the nucleon EDMs were extracted from the Hg data. 6)The EDM of a neutral atom is mainly induced by the nuclear Schiff moment, since the electron EDM is very small and the nuclear EDM is shielded by outside electrons owing to the Schiff theorem. 7) Nuclear Schiff moments for various nuclei were calculated in terms of the nuclear mean field theories 8), 9) and some collective models. 10), 11) However, up to now there has not yet been any nuclear shell model approaches.Recently, it was reported that the nuclear EDM would be measured directly by using an ionic atom instead of a neutral atom. 12), 13) For a neutral atom the nuclear EDM is completely shielded by the surrounding electrons. However, for an ionic atom the nuclear EDM is not shielded completely by electrons and thus it is meaningful to measure the EDM of the ionic atom.The Schiff moment is induced mainly by two different sources of mechanism. One comes from the nucleon intrinsic electric dipole moment. The other comes from the two-body nuclear interaction which violates parity (P ) and time-reversal symmetries. * )

Nuclear Schiff moments for the lowest1/2+states in Xe isotopes

“…In our previous paper [20], we calculated the EDMs and Schiff moments of Xe, Ba, and Ce isotopes arising from the intrinsic nucleon EDM in terms of the nuclear shell model. In this paper we estimate the Schiff moments for the lowest 1/2 + states of Xe isotopes around the mass 130 assuming two independent origins: one from the intrinsic nucleon EDM and the other from two-body interactions which break P and T invariance.…”

Shell Model Estimate of Electric Dipole Moments for Xe Isotopes

“…Since the explicit value ofḡ (I) πNN is unknown, one cannot tell which isospin component is the largest. It should be noted that the value observed in experiment should be a sum of these three components and also ingredients coming from other origins (like intrinsic nucleon EDMs [8]). …”

“…Theoretical calculations for the Schiff moments were carried out in various models [6,7]. In the previous papers [8][9][10], the nuclear EDMs and Schiff moments of Xe, Ba, and Ce isotopes were calculated. In this work, the nuclear wave functions are calculated in terms of the nuclear shell model and Schiff moments for the lowest 1/2 + states of Xe isotopes are estimated.…”

Linear programming analysis of the R-parity violation within EDM-constraints

“…(2.43) for 129 Xe nucleus, we use the result of the shell model [259,260]. For the calculations of the nuclear Schiff moments of the 199 Hg, 211 Rn, and 225 Ra, we use the results of the many-body calculation with mean-field approximation taking into account the deformation [261,262].…”