arXiv subjects

Vadim Rodin

Publications and source records attributed to Vadim Rodin.

23 records · Page 2Linked to original sources

arXiv2008

Anatomy of nuclear matrix elements for neutrinoless double-beta decay

We show that, within the Quasiparticle Random Phase Approximation (QRPA) and the renormalized QRPA (RQRPA) based on the Bonn CD nucleon-nucleon interaction, the competition between the pairing and the neutron-proton particle-particle and particle-hole interactions causes contributions to the neutrinoless double-beta decay matrix element to nearly vanish at internucleon distances of more than 2 or 3 fermis. As a result, the matrix element is more sensitive to short-range/high-momentum physics than one naively expects. We analyze various ways of treating that physics and quantify the uncertainty it produces in the matrix elements, with three different treatments of short-range correlations.

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arXiv2007

Neutron Skin and Giant Resonances in Nuclei

Some aspects, both experimental and theoretical, of extracting the neutron skin $ΔR$ from properties of isovector giant resonances are discussed. Existing proposals are critically reviewed. The method relying on the energy difference between the GTR and IAS is shown to lack sensitivity to $ΔR$. A simple explanation of the linear relation between the symmetry energy and the neutron skin is also given.

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arXiv2006

Uncertainties in the $0νββ$--decay nuclear matrix elements

The nuclear matrix elements $M^{0ν}$ of the neutrinoless double beta decay ($0νββ$) of most nuclei with known $2νββ$-decay rates are systematically evaluated using the Quasiparticle Random Phase Approximation (QRPA) and Renormalized QRPA (RQRPA). The experimental $2νββ$-decay rate is used to adjust the most relevant parameter, the strength of the particle-particle interaction. With such procedure the $M^{0ν}$ values become essentially independent on single-particle basis size, the axial vector quenching factor, etc. Theoretical arguments in favor of the adopted way of determining the interaction parameters are presented. It is suggested that most of the spread among the published $M^{0ν}$'s can be ascribed to the choices of implicit and explicit parameters, inherent to the QRPA method.

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arXiv2006

First application of the continuum-QRPA to description of the double beta decay

A continuum-QRPA approach to calculation of the $2νββ$- and $0νββ$-amplitudes has been formulated. For $^{130}$Te a regular suppression (about 20%) of the high-multipole contributions to the $0νββ$-amplitude has been found which can be associated with additional ground state correlations appearing from the transitions to collective states in the continuum. At the same time the total calculated $0νββ$-amplitude for $^{130}$Te gets suppressed by about 20% as compared to the result of the usual, discretized, QRPA.

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arXiv2002

Fully-Renormalized QRPA fulfills Ikeda sum rule exactly

The renormalized quasiparticle-RPA is reformulated for even-even nuclei using restrictions imposed by the commutativity of the phonon creation operator with the total particle number operator. This new version, Fully-Renormalized QRPA (FR-QRPA), is free from the spurious low-energy solutions. Analytical proof is given that the Ikeda sum rule is fullfiled within the FR-QRPA.

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