Ab initio calculation of the potential bubble nucleus 34Si
Duguet, T, Somà, V, Lecluse, S, Barbieri, Carlo and Navrátil, P (2017) Ab initio calculation of the potential bubble nucleus 34Si Physical Review C: Nuclear Physics, 95, 034319.

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Abstract
Background: The possibility that an unconventional depletion (referred to as a “bubble”) occurs in the center of the charge density distribution of certain nuclei due to a purely quantum mechanical effect has attracted theoretical and experimental attention in recent years. Based on a meanfield rationale, a correlation between the occurrence of such a semibubble and an anomalously weak splitting between low angularmomentum spinorbit partners has been further conjectured. Energy density functional and valencespace shell model calculations have been performed to identify and characterize the best candidates, among which 34 Si appears as a particularly interesting case. While the experimental determination of the charge density distribution of the unstable 34 Si is currently out of reach, ( d , p ) experiments on this nucleus have been performed recently to test the correlation between the presence of a bubble and an anomalously weak 1 / 2 − − 3 / 2 − splitting in the spectrum of 35 Si as compared to 37 S .Purpose: We study the potential bubble structure of 34 Si on the basis of the stateoftheart ab initio selfconsistent Green's function manybody method. Methods: We perform the first ab initio calculations of 34 Si and 36 S . In addition to binding energies, the first observables of interest are the charge density distribution and the charge rootmeansquare radius for which experimental data exist in 36 S . The next observable of interest is the lowlying spectroscopy of 35 Si and 37 S obtained from ( d , p ) experiments along with the spectroscopy of 33 Al and 35 P obtained from knockout experiments. The interpretation in terms of the evolution of the underlying shell structure is also provided. The study is repeated using several chiral effective field theory Hamiltonians as a way to test the robustness of the results with respect to input internucleon interactions. The convergence of the results with respect to the truncation of the manybody expansion, i.e., with respect to the manybody correlations included in the calculation, is studied in detail. We eventually compare our predictions to stateoftheart multireference energy density functional and shell model calculations. Results: The prediction regarding the (non)existence of the bubble structure in 34 Si varies significantly with the nuclear Hamiltonian used. However, demanding that the experimental charge density distribution and the rootmeansquare radius of 36 S be well reproduced, along with 34 Si and 36 S binding energies, only leaves the NNLO sat Hamiltonian as a serious candidate to perform this prediction. In this context, a bubble structure, whose fingerprint should be visible in an electron scattering experiment of 34 Si , is predicted. Furthermore, a clear correlation is established between the occurrence of the bubble structure and the weakening of the 1 / 2 − − 3 / 2 − splitting in the spectrum of 35 Si as compared to 37 S .Conclusions: The occurrence of a bubble structure in the charge distribution of 34 Si is convincingly established on the basis of stateoftheart ab initio calculations. This prediction will have to be reexamined in the future when improved chiral nuclear Hamiltonians are constructed. On the experimental side, present results act as a strong motivation to measure the charge density distribution of 34 Si in future electron scattering experiments on unstable nuclei. In the meantime, it is of interest to perform oneneutron removal on 34 Si and 36 S in order to further test our theoretical spectral strength distributions over a wide energy range.
Item Type:  Article  

Subjects :  Physics  
Divisions :  Faculty of Engineering and Physical Sciences > Physics  
Authors : 


Date :  24 March 2017  
Identification Number :  10.1103/PhysRevC.95.034319  
Copyright Disclaimer :  ©2017 American Physical Society  
Related URLs :  
Depositing User :  Symplectic Elements  
Date Deposited :  26 Apr 2017 15:26  
Last Modified :  13 Sep 2017 16:00  
URI:  http://epubs.surrey.ac.uk/id/eprint/814041 
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