/ Theory-Nucl

Nonlinear higher quasiparticle random phase approximation

Smetana, Adam (IEAP CTU, Prague) ; Šimkovic, Fedor (Dubna, JINR) ; Štefánik, Dušan (Comenius U.) ; Krivoruchenko, Mikhail (Moscow, MIPT)

Published in: AIP Conf.Proc.
Year: 2017
Vol.: 1894    Num./Issue: 1
Page No: 020021
Year: 2017-10-16 published

Abstract: We develop a new approach to describe nuclear states of multiphonon origin, motivated by the necessity for a more accurate description of matrix elements of neutrinoless double-beta decay. Our approach is an extension of the Quasiparticle Random Phase Approximation (QRPA), in which nonlinear phonon operators play an essential role. Before applying the nonlinear higher QRPA (nhQRPA) to realistic problems, we test its efficiency with exactly solvable models. The first considered model is equivalent to a harmonic oscillator. The nhQRPA solutions follow from the standard QRPA equation, but for nonlinear phonon operators defined for each individual excited state separately. The second exactly solvable model is the proton-neutron Lipkin model that describes successfully not only energy spectrum of nuclei, but also beta-decay transitions. Again, we reproduce exactly the numerical solutions in the nhQRPA framework. We show in particular that truncation of the nonlinear phonon operators leads to an approximation similar to the self-consistent second QRPA, given the phonon operators are defined with a constant term. The test results demonstrate that the proposed nhQRPA is a promising tool for a realistic calculation of energy spectra and nuclear transitions.

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Total numbers of views: 100
Numbers of unique views: 50
DOI: 10.1063/1.5007646
 Record created 2017-11-02, last modified 2017-11-02

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