Nuclear Theory·nucl-th

Monday·July 27, 2020

5 papers—3 primary·2 cross-listed

01
[Submitted on 24 Jul 2020]
High-Spin Doublet Band Structures in odd-odd $^{194 - 200}$ Tl isotopes
S. Jehangir · I. Maqbool · G.H. Bhat · J.A. Sheikh · R. Palit · N. Rather
The basis space in the triaxial projected shell model (TPSM) approach is generalized for odd-odd nuclei to include two-neutron and two-proton configurations on the basic one-neutron coupled to one-proton quasiparticle state. The generalization allows to investigate odd-odd nuclei beyond the band crossing region and as a first application of this development, high-spin band structures recently observed in odd-odd $^{194 - 200}$ Tl isotopes are investigated. In some of these isotopes, the doublet band structures observed after the band crossing have been conjectured to arise from the spontaneous breaking of the chiral symmetry. The driving configuration of the chiral symmetry in these odd-odd isotopes is one-proton and three-neutrons rather than the basic one-proton and one-neutron as already observed in many other nuclei. It is demonstrated using the TPSM approach that energy differences of the doublet bands in $^{194}$ Tl and $^{198}$ Tl are, indeed, small. However, the differences in the calculated transition probabilities are somewhat larger than what is expected in the chiral symmetry limit. Experimental data on the transition probabilities is needed to shed light on the chiral nature of the doublet bands.
Comments:
11 pages, 17 figures, to appear in EPJA
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2007.12347 [pdf]
EPJA(2020)·10 citations
02
[Submitted on 23 Jul 2020]
On feasibility of azimuthal flow studies with Principal Component Analysis
Igor Altsybeev
It is shown that the Principal Component Analysis applied to azimuthal single-particle distributions allows to perform flow analysis in ways that are analogous to the traditional approaches based on multi-particle correlations. In particular, symmetric cumulants are considered. It is demonstrated also that statistical fluctuations due to a finite number of particles per event practically do not play a role for higher order PCA-based cumulants.
Comments:
5 pages, 2 figures. Presented at WWND-2020
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2007.12524 [pdf]
J.Phys.Conf.Ser.(2020)·0 citations
03
[Submitted on 24 Jul 2020]
Two-neutron transfer reactions as a tool to study the interplay between shape coexistence and quantum phase transitions
J.E. García-Ramos · J.M. Arias · A. Vitturi
The goal of this study is to find an observable that could distinguish between both phenomena, shape coexistence and quantum phase transitions. The selected observable to be analyzed is the two-neutron transfer intensity between the 0+ states in the parent and daughter nuclei. The framework in which the study is done is the Interacting Boson Model (IBM), including its version with configuration mixing (IBM-CM). In order to generate the wave functions of the isotope chains of interest, needed for calculating transfer intensities, previous systematic studies with IBM and IBM-CM are taken without changing the parameters. Results for two-neutron transfer intensities are presented for Zr, Hg and Pt isotopic chains using IBM-CM and, moreover, the same is done for Zr, Pt and Sm isotopic chains using IBM with just a single configuration, i.e., without using configuration mixing. In the case of Zr, the two-neutron transfer intensities between the ground states provide a clear observable indicating that normal and intruder configurations coexist in the low-lying spectrum and that they cross at A=98->100, and this could allow to disentangle whether or not shape coexistence is inducing a given QPT. In the case of Pt, where shape coexistence is present and the regular and the intruder configurations cross for the ground state, there is almost no influence in the value of the two-neutron transfer, neither in the case of Hg where the ground state always has regular nature. For the Sm isotope chain that is one of the quantum phase transition paradigms, the value of the two-neutron transfer is strongly affected.
Comments:
To be published in the Chinese Physics C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2007.12629 [pdf]
CPC(2020)·4 citations
04
[Submitted on 24 Jul 2020] (cross-list from hep-ph)
A theoretical analysis of the semileptonic decays $η^{(')} \to π^{0} l^{+} l^{-}$ and $η^{'} \to η l^{+} l^{-}$
Rafel Escribano🇪🇸 · Emilio Royo🇪🇸
A complete theoretical analysis of the $C$ -conserving semileptonic decays $η^{(')} \to π^{0} l^{+} l^{-}$ and $η^{'} \to η l^{+} l^{-}$ ( $l = e$ or $μ$ ) is carried out within the framework of the Vector Meson Dominance (VMD) model. An existing phenomenological model is used to parametrise the VMD coupling constants and the associated numerical values are obtained from an optimisation fit to $V \to P γ$ and $P \to V γ$ radiative decays ( $V = ρ^{0}$ , $ω$ , $ϕ$ and $P = π^{0}$ , $η$ , $η^{'}$ ). The decay widths and dilepton energy spectra for the two $η \to π^{0} l^{+} l^{-}$ processes obtained using this approach are compared and found to be in good agreement with other results available in the published literature. Theoretical predictions for the four $η^{'} \to π^{0} l^{+} l^{-}$ and $η^{'} \to η l^{+} l^{-}$ decay widths and dilepton energy spectra are calculated and presented for the first time in this work.
Comments:
11 pages, 2 figures, 1 table; v2 includes estimated errors coming from the dependence on the model and a detailed explanation of the structure of the $V P γ$ vertex; v3 corrects eqs. (6) and (15), includes discussions on the Feynman integral numerical computations and the use of the energy-dependent width for the $ρ$ propagator, as well as corrected numerical results in Table I and Fig. 2
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2007.12467 [pdf]
EPJC(2020)·23 citations
05
[Submitted on 24 Jul 2020] (cross-list from hep-ph)
Pseudoscalar and vector open-charm mesons at finite temperature
Glòria Montaña🇪🇸 · Àngels Ramos🇪🇸 · Laura Tolos🇩🇪 · Juan M. Torres-Rincon🇩🇪
Vacuum and thermal properties of pseudoscalar and vector charm mesons are analyzed within a self-consistent many-body approach, employing a chiral effective field theory that incorporates heavy-quark spin symmetry. Upon unitarization of the vacuum interaction amplitudes for the scattering of charm mesons off light mesons in a fully coupled-channel basis, new dynamically generated states are searched. The imaginary-time formalism is employed to extend the calculation to finite temperatures up to $T = 150$ MeV. Medium-modified spectral shapes of the $D$ , $D^{*}$ , $D_{s}$ and $D_{s}^{*}$ mesons are provided. The temperature dependence of the masses and decay widths of the nonstrange $D_{0}^{*}$ (2300) and $D_{1}^{*}$ (2430) mesons, both showing a double-pole structure in the complex-energy plane, is also reported, as well as that of the $D_{s 0}^{*}$ (2317) and $D_{s 1}^{*}$ (2460) resonances and other states not yet identified experimentally. Being the first calculation incorporating open-charm vector mesons at finite temperature in a self-consistent fashion, it brings up the opportunity to discuss the medium effects on the open charm sector under the perspective of chiral and heavy-quark spin symmetries.
Comments:
47 pages, 10 figures, 8 tables. References added and typos removed. Additional explanations on unitarization procedure, medium modifications of pion, and cutoff parameter dependence. Version accepted for publication in Physical Review D journal
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2007.12601 [pdf]
PRD(2020)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE

High-Spin Doublet Band Structures in odd-odd 194−200Tl isotopes

On feasibility of azimuthal flow studies with Principal Component Analysis

Two-neutron transfer reactions as a tool to study the interplay between shape coexistence and quantum phase transitions

A theoretical analysis of the semileptonic decays η(′)→π0l+l− and η′→ηl+l−

Pseudoscalar and vector open-charm mesons at finite temperature

Affiliations

High-Spin Doublet Band Structures in odd-odd $^{194 - 200}$ Tl isotopes

A theoretical analysis of the semileptonic decays $η^{(')} \to π^{0} l^{+} l^{-}$ and $η^{'} \to η l^{+} l^{-}$