Nuclear Theory·nucl-th

Monday·April 6, 2020

7 papers—2 primary·5 cross-listed

01
[Submitted on 3 Apr 2020]
Landscape of pear-shaped even-even nuclei
Yuchen Cao🇺🇸 · Sylvester E. Agbemava🇺🇸 · Anatoli V. Afanasjev🇺🇸 · Witold Nazarewicz🇺🇸 · Erik Olsen🇧🇪
The phenomenon of reflection-asymmetric nuclear shapes is relevant to nuclear stability, nuclear spectroscopy, nuclear decays and fission, and the search for new physics beyond the standard model. Global surveys of ground-state octupole deformation, performed with a limited number of models, suggest that the number of pear-shaped isotopes is fairly limited across the nuclear landscape. We carry out global analysis of ground-state octupole deformations for particle-bound even-even nuclei with $Z \leq 110$ and $N \leq 210$ using nuclear density functional theory (DFT) with several non-relativistic and covariant energy density functionals. In this way, we can identify the best candidates for reflection-asymmetric shapes. The calculations are performed in the frameworks of axial reflection-asymmetric Hartree-Fock-Bogoliubov theory and relativistic Hartree-Bogoliubov theory using DFT solvers employing harmonic oscillator basis expansion. We consider five Skyrme and four covariant energy density functionals. We predict several regions of ground-state octupole deformation. In addition to the "traditional" regions of neutron-deficient actinide nuclei around $^{224}$ Ra and neutron-rich lanthanides around $^{146}$ Ba, we identified vast regions of reflecion-asymmetric shapes in very neutron-rich nuclei around $^{200}$ Gd and $^{288}$ Pu, as well as in several nuclei around $^{112}$ Ba. Our analysis suggests several promising candidates with stable ground-state octupole deformation, primarily in the neutron-deficient actinide region, that can be reached experimentally. Detailed comparison between Skyrme and covariant models is performed.
Comments:
13 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2004.01319 [pdf]
PRC(2020)·90 citations
02
[Submitted on 3 Apr 2020]
Existence of higher nodal band states with $α$ + $^{48}$ Ca cluster structure in $^{52}$ Ti
S. Ohkubo
It is shown that recently observed $α$ cluster states a few MeV above the $α$ threshold energy in $^{52}$ Ti correspond to the higher nodal band states with the $α$ + $^{48}$ Ca cluster structure, i.e. a vibrational mode in which the intercluster relative motion is excited. The existence of the higher nodal states in the $^{48}$ Ca core region in addition to the well-known higher nodal states in $^{20}$ Ne and $^{44}$ Ti reinforces the importance of the concept of vibrational motion due to clustering even in medium-weight nuclei with a $j j$ -shell closed core. The higher nodal band and the shell-like ground band in $^{52}$ Ti are described in a unified way by a Luneburg lens-like deep local potential due to the Pauli principle, which explains the emergence of backward angle anomaly (anomalous large angle scattering (ALAS)) at low energies, prerainbows at intermediate energies and nuclear rainbows at high energies in $α$ + $^{48}$ Ca scattering. The existence of a $K = 0^{-}$ $α$ cluster band analog to $^{44}$ Ti midway between the ground band and the higher nodal band is inevitably predicted.
Comments:
6 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2004.01363 [pdf]
PRC(2020)·8 citations
03
[Submitted on 3 Apr 2020] (cross-list from hep-ph)
Heavy vector and axial-vector $D$ mesons in hot magnetized asymmetric nuclear matter
Rajesh Kumar🇮🇳 · Rahul Chhabra🇮🇳 · Arvind Kumar🇮🇳
We observed the impact of finite magnetic field on the in-medium mass and decay constant of isospin averaged vector $D^{*} (D^{*^{+}}, D^{*^{0}})$ and axial-vector $D_{1} (D_{1}^{+}, D_{1}^{0})$ mesons. The quark and gluon condensates of the nuclear medium at finite magnetic field, temperature, isospin asymmetry, and density have been obtained by the meson exchange scalar fields within the chiral SU(3) model. The medium attributes modify the scalar and vector density of nuclear medium and this variation reflects in the in-medium mass and decay constant of spin 1 $D$ mesons. We calculate these observables by comparing the Operator Product Expansion (OPE) and the phenomenological side in the QCD Sum Rules. In the results, we observed a positive mass shift for charged vector and axial-vector $D$ mesons with respect to magnetic field. For neutral vector (axial-vector) $D$ mesons we observed negative (positive) mass shift as a function of magnetic field. In the application part, we calculate the in-medium partial decay width of the process $D_{s}^{*}$ (2715/2860) $\to$ $D^{*} K$ by using $^{3} P_{0}$ model. The in-medium effects are incorporated through the in-medium masses of $D^{*}$ and $K$ mesons.
Comments:
36 Pages, 11 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2004.01379 [pdf]
EPJA(2020)·12 citations
04
[Submitted on 3 Apr 2020] (cross-list from hep-ph)
The scalar $f_{0} (500)$ and $f_{0} (980)$ resonances and vector mesons in the single Cabibbo-suppressed decays $Λ_{c} \to p K^{+} K^{-}$ and $p π^{+} π^{-}$
Zhe Wang🇨🇳 · Yan-Yan Wang🇨🇳 · En Wang🇨🇳 · De-Min Li🇨🇳 · Ju-Jun Xie🇨🇳
In the chiral unitary approach, we have studied the single Cabibbo-suppressed decays $Λ_{c} \to p K^{+} K^{-}$ and $Λ_{c} \to p π^{+} π^{-}$ by taking into account the $s$ -wave meson-meson interaction as well as the contributions from the intermediate vectors $ϕ$ and $ρ^{0}$ . Our theoretical results for the ratios of the branching fractions of $Λ_{c} \to p K ˉ^{* 0}$ and $Λ_{c} \to p ω$ with respect to the one of $Λ_{c} \to pϕ$ are in agreement with the experimental data. Within the picture that the scalar resonances $f_{0} (500)$ , $f_{0} (980)$ , and $a_{0} (980)$ are dynamically generated from the pseudoscalar-pseudoscalar interactions in $s$ -wave, we have calculated the $K^{+} K^{-}$ and $π^{+} π^{-}$ invariant mass distributions respectively for the decays $Λ_{c} \to p K^{+} K^{-}$ and $Λ_{c} \to p π^{+} π^{-}$ . One can find a broad bump structure for the $f_{0} (500)$ and a narrow peak for the $f_{0} (980)$ in the $π^{+} π^{-}$ invariant mass distribution of the decay $Λ_{c} \to p π^{+} π^{-}$ . For the $K^{+} K^{-}$ invariant mass distribution, in addition to the narrow peak for the $ϕ$ meson, there is an enhancement structure near the $K^{+} K^{-}$ threshold mainly due to the contribution from the $f_{0} (980)$ . Both the $π^{+} π^{-}$ and $K^{+} K^{-}$ invariant mass distributions are compatible with the BESIII measurement. We encourage our experimental colleagues to measure these two decays, which would be helpful to understand the nature of the $f_{0} (500)$ , $f_{0} (980)$ , and $a_{0} (980)$ .
Comments:
14 pages, 10 figures, the version to be published in EPJC
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2004.01438 [pdf]
EPJC(2020)·38 citations
05
[Submitted on 28 Mar 2020] (cross-list from cond-mat.str-el)
Exploring anomalies by many-body correlations
Klaus Morawetz🇧🇷
The quantum anomaly can be written alternatively into a form violating conservation laws or as non-gauge invariant currents seen explicitly on the example of chiral anomaly. By reinterpreting the many-body averaging, the connection to Pauli-Villars regularization is established which gives the anomalous term a new interpretation as arising from quantum fluctuations by many-body correlations at short distances. This is exemplified by using an effective many-body quantum potential which realizes quantum Slater sums by classical calculations. It is shown that these quantum potentials avoid the quantum anomaly but approaches the same anomalous result by many-body correlations. A measure for the quality of quantum potentials is suggested to describe these quantum fluctuations in the mean energy. Consequently quantum anomalies might be a short-cut way of single-particle field theory to account for many-body effects. This conjecture is also supported since the chiral anomaly can be derived by a completely conserving quantum kinetic theory.
Subjects:
Strongly Correlated Electrons (cond-mat.str-el); Quantum Gases (cond-mat.quant-gas); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2004.01507 [pdf]
Phys.Status Solidi B(2022)·0 citations
06
[Submitted on 3 Apr 2020] (cross-list from hep-ph)
Pion and Kaon parton distributions in the QCD instanton vacuum
Arthur Kock🇺🇸 · Yizhuang Liu🇨🇳 · Ismail Zahed🇺🇸
We discuss a general diagrammatic description of n-point functions in the QCD instanton vacuum that resums planar diagrams, enforces gauge invariance and spontaneously broken chiral symmetry. We use these diagrammatic rules to derive the pion and kaon quasi-parton amplitude and distribution functions at leading order in the instanton packing fraction for large but finite momentum. The instanton and anti-instanton zero modes and non-zero modes are found to contribute to the quasi-distributions, but the latter are shown to drop out in the large momentum limit. The pertinent pion and kaon parton distribution amplitudes and functions are made explicit at the low renormalization scale fixed by the inverse instanton size. Assuming that factorization holds, the pion parton distributions are evolved to higher renormalization scales with one-loop DGLAP and compared to existing data.
Comments:
28 pages, 14 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2004.01595 [pdf]
PRD(2020)·42 citations
07
[Submitted on 3 Apr 2020] (cross-list from hep-lat)
Parton Distribution Functions from Ioffe Time Pseudodistributions from Lattice Calculations: Approaching the Physical Point
Bálint Joó🇺🇸 · Joseph Karpie🇺🇸 · Kostas Orginos🇺🇸 · Anatoly V. Radyushkin🇺🇸 · David G. Richards🇺🇸 · Savvas Zafeiropoulos🇫🇷
We present results for the unpolarized parton distribution function of the nucleon computed in lattice QCD at the physical pion mass. This is the first study of its kind employing the method of Ioffe time pseudo-distributions. Beyond the reconstruction of the Bjorken- $x$ dependence we also extract the lowest moments of the distribution function using the small Ioffe time expansion of the Ioffe time pseudo-distribution. We compare our findings with the pertinent phenomenological determinations.
Comments:
v2, 8 pages, 6 figures, matches published version, to appear in Phys.Rev.Lett
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2004.01687 [pdf]
PRL(2020)·103 citations

Affiliations

first authorsco-authorsvia INSPIRE

Landscape of pear-shaped even-even nuclei

Existence of higher nodal band states with α+48Ca cluster structure in 52Ti

Heavy vector and axial-vector D mesons in hot magnetized asymmetric nuclear matter

The scalar f0​(500) and f0​(980) resonances and vector mesons in the single Cabibbo-suppressed decays Λc​→pK+K− and pπ+π−

Exploring anomalies by many-body correlations

Pion and Kaon parton distributions in the QCD instanton vacuum

Parton Distribution Functions from Ioffe Time Pseudodistributions from Lattice Calculations: Approaching the Physical Point

Affiliations

Existence of higher nodal band states with $α$ + $^{48}$ Ca cluster structure in $^{52}$ Ti

Heavy vector and axial-vector $D$ mesons in hot magnetized asymmetric nuclear matter

The scalar $f_{0} (500)$ and $f_{0} (980)$ resonances and vector mesons in the single Cabibbo-suppressed decays $Λ_{c} \to p K^{+} K^{-}$ and $p π^{+} π^{-}$