Nuclear Theory·nucl-th

Monday·November 28, 2022

22 papers—12 primary·10 cross-listed

01
[Submitted on 24 Nov 2022]
Supersolidity of $α$ cluster structure in $^{40}$ Ca
S. Ohkubo
$α$ cluster structure in nuclei has been long understood based on the geometrical configuration picture. By using the spatially localized Brink $α$ cluster model in the generator coordinate method, it is shown that the $α$ cluster structure has the apparently opposing duality of crystallinity and condensation, a property of supersolids. To study the condensation aspects of the $α$ cluster structure a field theoretical superfluid cluster model (SCM) is introduced, in which the order parameter of condensation is incorporated by treating rigorously the Nambu-Goldstone mode due to spontaneous symmetry breaking of the global phase. The $α$ cluster structure of $^{40}$ Ca, which has been understood in the crystallinity picture, is studied by the SCM with ten $α$ clusters. It is found that the $α$ cluster structure of $^{40}$ Ca is reproduced by the SCM in addition to $^{12}$ C reported in a previous paper, which gives support to the duality of the $α$ cluster structure. The emergence of the mysterious $0^{+}$ state at the lowest excitation energy near the $α$ threshold energy is understood to be a manifestation of the Nambu-Goldstone zero mode, a soft mode, due to the condensation aspect of the duality similar to the Hoyle state in $^{12}$ C. The duality of $α$ cluster structure with incompatible crystallinity and coherent wave nature due to condensation is the consequence of the Pauli principle, which causes clustering.
Comments:
12 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2211.13381 [pdf]
PRC(2022)·2 citations
02
[Submitted on 24 Nov 2022]
Stability of the manifold boundary approximation method for reductions of nuclear structure models
M. Imbrišak · K. Nomura
The framework of nuclear energy density functionals has been employed to describe nuclear structure phenomena for a wide range of nuclei. Recently, statistical properties of a given nuclear model, such as parameter confidence intervals and correlations, have received much attention, particularly when one tries to fit complex models. We apply information-theoretic methods to investigate stability of model reductions by the manifold boundary approximation method (MBAM). In an illustrative example of the density-dependent point-coupling model of the relativistic energy density functional, utilizing Monte Carlo simulations, it is found that main conclusions obtained from the MBAM procedure are stable under variation of the model parameters. Furthermore, we find that the end of the geodesic occurs when the determinant of the Fisher information metric vanishes, thus effectively separating the parameter space into two disconnected regions.
Comments:
12 pages, 7 figures, 1 table. arXiv admin note: text overlap with arXiv:1606.08617 by other authors
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2211.13457 [pdf]
PRC(2023)·2 citations
03
[Submitted on 24 Nov 2022]
Employing ternary fission of $^{242}$ Pu as a probe of very neutron rich matter
J.B. Natowitz · H. Pais · G. Röpke
Detailed assessments of the ability of recent theoretical approaches to modeling existing experimental data for ternary fission confirm earlier indications that the dominant mode of cluster formation in ternary fission is clusterization in very neutron rich, very low density, essentially chemically equilibrated, nucleonic matter. An extended study and comparison of these approaches applied to ternary fission yields in the thermal neutron induced reaction $^{241}$ Pu( $n_{th}$ ,f) has been undertaken to refine the characterization of the source matter. The resonance gas approximation has been improved taking in-medium effects on the binding energies into account. A temperature of 1.29 MeV, density of $6.7 \times 1 0^{- 5}$ nucleons/fm $^{3}$ and proton fraction $Y_{p}$ = 0.035 are found to provide a good representation of yields of the ternary emitted light particles and clusters. In particular, results for $Z = 1$ and 2 isotopes are presented. Isotopes with larger $Z$ are discussed, and the roles of medium and continuum effects, even at very low density are illustrated.
Comments:
19 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2211.13492 [pdf]
PRC(2023)·10 citations
04
[Submitted on 24 Nov 2022]
Jet radius and momentum splitting fraction with dynamical grooming in heavy-ion collisions
Lei Wang🇨🇳 · Jin-Wen Kang🇨🇳 · Qing Zhang🇨🇳 · Shuwan Shen🇨🇳 · Wei Dai🇨🇳 · Ben-Wei Zhang🇨🇳 · Enke Wang🇨🇳
We investigate the medium modifications of momentum splitting fraction and groomed jet radius with both dynamical grooming and soft drop algorithms in heavy-ion collisions. In the calculation, the partonic spectrum of initial hard scattering in p+p collisions is provided by the event generator PYTHIA 8, and the energy loss of fast parton traversing in a hot/dense QCD medium is simulated with the Linear Boltzmann Transport (LBT) model. We predict the normalized distributions of the groomed jet radius $θ_{g}$ and momentum splitting fraction $z_{g}$ with the dynamical grooming algorithm in Pb+Pb collisions at $s_{NN}$ = 5.02 TeV, then compare these quantities in dynamical grooming at $a = 0.1$ , with that in soft drop at $z_{cut} = 0.1$ and $β = 0$ . It is found that the normalized distribution ratios Pb+Pb/p+p with respect to $z_{g}$ in $z_{cut} = 0.1$ , $β = 0$ soft drop case are close to unity and those in $a = 0.1$ dynamical grooming case show enhancement at small $z_{g}$ , and Pb+Pb/p+p with respect to $θ_{g}$ in the dynamical grooming case demonstrate weaker modification than those in the soft drop counterparts. We further calculate the groomed jet number averaged momentum splitting fraction $⟨ z_{g} ⟩_{jets}$ and averaged groomed jet radius $⟨ θ_{g} ⟩_{jets}$ in p+p and A+A for both grooming cases in three $p_{T}^{ch, jet}$ intervals, and find that the originally generated well balanced groomed jets will become more momentum imbalanced and less jet size narrowing due to jet quenching, and weaker medium modification of $z_{g}$ and $θ_{g}$ in $a = 0.1$ dynamical grooming case than in the soft drop counterparts.
Comments:
7 pages, 3 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2211.13674 [pdf]
Chin.Phys.Lett.(2023)·14 citations
05
[Submitted on 25 Nov 2022]
$(I, J^{P}) = (1, 1/ 2^{+})$ $Σ N N$ quasibound state
H. Garcilazo🇲🇽 · A. Valcarce🇪🇸
JLab has recently found indications of the possible existence of a $Σ N N$ resonance at $(3.14 \pm 0.84) - i (2.28 \pm 1.2)$ MeV. In the past, using models that exploit symmetries between the two-baryon sector with and without strangeness, hyperon-nucleon interactions have been derived that reproduce the experimental data of the strangeness $- 1$ sector. We make use of these interactions to review existing Faddeev studies of the $Λ N N$ - $Σ N N$ system that show theoretical evidences about a $(I, J^{P}) = (1, 1/ 2^{+})$ $Σ N N$ quasibound state near threshold. The calculated position of the pole is at 2.92 $- i$ 2.17 MeV, in reasonable agreement with the experimental findings.
Comments:
7 pages, 2 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2211.13970 [pdf]
Symmetry(2022)·8 citations
06
[Submitted on 25 Nov 2022]
Deep-neural-network approach to solving the ab initio nuclear structure problem
Yilong Yang · Pengwei Zhao
Predicting the structure of quantum many-body systems from the first principles of quantum mechanics is a common challenge in physics, chemistry, and material science. Deep machine learning has proven to be a powerful tool for solving condensed matter and chemistry problems, while for atomic nuclei it is still quite challenging because of the complicated nucleon-nucleon interactions, which strongly couple the spatial, spin, and isospin degrees of freedom. By combining essential physics of the nuclear wave functions and the strong expressive power of artificial neural networks, we develop FeynmanNet, a deep-learning variational quantum Monte Carlo approach for \emph{ab initio} nuclear structure. We show that FeynmanNet can provide very accurate solutions of ground-state energies and wave functions for $^{4}$ He, $^{6}$ Li, and even up to $^{16}$ O as emerging from the leading-order and next-to-leading-order Hamiltonians of pionless effective field theory. Compared to the conventional diffusion Monte Carlo approaches, which suffer from the severe inherent fermion-sign problem, FeynmanNet reaches such a high accuracy in a variational way and scales polynomially with the number of nucleons. Therefore, it paves the way to a highly accurate and efficient \emph{ab initio} method for predicting nuclear properties based on the realistic interactions between nucleons.
Comments:
16 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); cond-mat.dis-nn (cond-mat.dis-nn); Quantum Physics (quant-ph)
arXiv:
2211.13998 [pdf]
PRC(2023)·44 citations
07
[Submitted on 25 Nov 2022]
Do short range correlations inhibit the appearance of the nuclear pasta?
Mateus R. Pelicer🇧🇷 · Débora P. Menezes🇧🇷 · Mariana Dutra🇧🇷 · Odilon Lourenço🇧🇷
It is well known that strongly correlated neutron-proton pairs, the short-range correlations (SRC), can modify many of the nuclear properties. In this work we have introduced, for the first time, short range correlations in the calculation of the nuclear pasta phase at zero temperature and checked how they affect its size and internal structure. We have used two different parameterizations of relativistic models in a mean field approximation and the coexistence phase approximation as a first estimation of the effects. We have seen that for very asymmetric neutron-proton-electon matter, the pasta phase shrinks considerably as compared with the results without SRC and all internal structures vanish, except the simple spherically symmetric one, the droplets. Our results indicate a possible disappearance of these complicated structures as the temperature increases.
Comments:
8 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2211.14002 [pdf]
EPJA(2023)·5 citations
08
[Submitted on 25 Nov 2022]
Microscopic description of $α$ , $2 α$ , and cluster decays of $^{216 - 220}$ Rn and $^{220 - 224}$ Ra
J. Zhao🇨🇳 · J.-P. Ebran🇫🇷 · L. Heitz🇫🇷 · E. Khan🇫🇷 · F. Mercier🇫🇷 · T. Niksic🇭🇷 · D. Vretenar🇭🇷
Alpha and cluster decays are analyzed for heavy nuclei located above $^{208}$ Pb on the chart of nuclides: $^{216 - 220}$ Rn and $^{220 - 224}$ Ra, that are also candidates for observing the $2 α$ decay mode. A microscopic theoretical approach based on relativistic Energy Density Functionals (EDF), is used to compute axially-symmetric deformation energy surfaces as functions of quadrupole, octupole and hexadecupole collective coordinates. Dynamical least-action paths for specific decay modes are calculated on the corresponding potential energy surfaces. The effective collective inertia is determined using the perturbative cranking approximation, and zero-point and rotational energy corrections are included in the model. The predicted half-lives for $α$ -decay are within one order of magnitude of the experimental values. In the case of single $α$ emission, the nuclei considered in the present study exhibit least-action paths that differ significantly up to the scission point. The differences in alpha-decay lifetimes are not only driven by Q values, but also by variances of the least-action paths prior to scission. In contrast, the $2 α$ decay mode presents very similar paths from equilibrium to scission, and the differences in lifetimes are mainly driven by the corresponding Q values. The predicted $^{14}$ C cluster decay half-lives are within three orders of magnitudes of the empirical values, and point to a much more complex pattern compared to the alpha-decay mode.
Comments:
9 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2211.14135 [pdf]
PRC(2023)·20 citations
09
[Submitted on 25 Nov 2022]
Studying the process $γ d \to π^{0} η d$
A. Martinez Torres🇧🇷 · K. P. Khemchandani🇧🇷 · E. Oset🇪🇸
In these proceedings we present our recent results on the study of the process $γ d \to π^{0} η d$ , where the existence of a dibaryon in the $η d$ invariant mass distribution has been recently claimed. As we will show, many of the relevant aspects observed in the experiment, as the shift of the $η d$ and $π d$ invariant mass distributions with respect to phase space can be described with our model, where no dibaryon is formed. Instead, we consider the interaction of the $γ$ with the nucleons forming the deuteron to proceed through $γ N \to Δ (1700) \to η Δ (1232) \to η π^{0} N$ , followed by the rescattering of the $π$ and $η$ with the other nucleon of the deuteron. Theoretical uncertainties related to different parameterizations of the deuteron wave function are investigated
Comments:
Contribution to the proceedings of the 4th Jagiellonian Symposium on Advances in Particle Physics and Medicine, 10-15 July 2022. arXiv admin note: text overlap with arXiv:2205.00948
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2211.14148 [pdf]
Acta Phys.Polon.A(2022)·1 citation
10
[Submitted on 25 Nov 2022]
Exotic properties of N^*(1895) and its impact on photoproduction of light hyperons
K. P. Khemchandani🇧🇷 · A. Martinez Torres🇧🇷 · Sang-Ho Kim🇰🇷 · Seung-il Nam🇰🇷 · A. Hosaka🇯🇵
In this work, we outline the findings of our recent study of the properties of $N^{*} (1895)$ and its consequential impacts on the cross sections of the photoproduction of $Λ (1405)$ . Further, we discuss the possibility of the existence of an isovector state, with the mass similar to $Λ (1405)$ , which we refer to as $Σ (1400)$ . With the idea of motivating experimental investigations of $Σ (1400)$ , we have studied its photoproduction process and determined the respective cross sections and polarization observables. We have studied also the coupling of $N^{*} (1895)$ to $K Σ (1400)$ and found that it gives an important contribution to the cross sections near the threshold. In the process, we have determined the branching ratios of the decay of $N^{*} (1895)$ , to the final states involving $Λ (1405)$ and $Σ (1400)$ , to be in the range of 6-7 MeV. Our findings can motivate consideration of alternative processes in partial wave analyses of experimental data, when studying the properties of $N^{*} (1895)$ .
Comments:
Proceedings for the 4th Jagiellonian Symposium on Advances in Particle Physics and Medicine, organised by the Jagiellonian University in Krakow, with the address and acknowledgments updated for one of the authors
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2211.14167 [pdf]
Acta Phys.Polon.A(2022)·2 citations
11
[Submitted on 25 Nov 2022]
Density-Induced Hadron-Quark Crossover via the Formation of Cooper Triples
Hiroyuki Tajima🇯🇵 · Shoichiro Tsutsui🇯🇵 · Takahiro M. Doi🇯🇵 · Kei Iida🇯🇵
We discuss the hadron--quark crossover accompanied by the formation of Cooper triples (three-body counterpart of Cooper pairs) by analogy with the Bose--Einstein condensate to Bardeen--Cooper--Schrieffer crossover in two-component fermionic systems. Such a crossover is different from a phase transition, which often involves symmetry breaking. We calculate the in-medium three-body energy from the three-body $T$ -matrix with a phenomenological three-body force characterizing a bound hadronic state in vacuum. With increasing density, the hadronic bound-state pole smoothly undergoes a crossover toward the Cooper triple phase where the in-medium three-body clusters coexist with the quark Fermi sea. The relation to the quarkyonic matter model can also be found in a natural manner.
Comments:
8 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Quantum Gases (cond-mat.quant-gas); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2211.14194 [pdf]
Symmetry(2023)·7 citations
12
[Submitted on 25 Nov 2022]
Towards microscopic optical potentials in deformed nuclei
Andrea Idini · Jimmy Rotureau · Johan Boström · Jimmy Ljungberg · B. Gillis Carlsson
A microscopic and consistent description of both nuclear structure and reactions is instrumental to extend the predictivity of models calculating scattering observables. In particular, this is crucial in the case of exotic nuclei not yet discovered. In this manuscript, we will present the plan of the Lund effort for a symmetry breaking description of bound and scattering observables using a generator coordinate method model based on an effective Hamiltonian constrained with a (Skyrme) functional. Following this, we will illustrate the steps to construct an optical potential for deformed nuclei from microscopic wavefunctions obtained with projected generator coordinate method from Hartree-Fock-Bogoliubov basis.
Comments:
3 pages, 1 figure, proceeding INPC 2022, Cape Town, South Africa
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2211.14263 [pdf]
J.Phys.Conf.Ser.(2023)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE