Nuclear Theory·nucl-th

Thursday·December 9, 2021

10 papers—5 primary·5 cross-listed

01
[Submitted on 7 Dec 2021]
Natural orbitals for the ab initio no-core configuration interaction approach
Patrick J. Fasano🇺🇸 · Chrysovalantis Constantinou🇺🇸 · Mark A. Caprio🇺🇸 · Pieter Maris🇺🇸 · James P. Vary🇺🇸
Ab initio no-core configuration interaction (NCCI) calculations for the nuclear many-body problem have traditionally relied upon an antisymmetrized product (Slater determinant) basis built from harmonic oscillator orbitals. The accuracy of such calculations is limited by the finite dimensions which are computationally feasible for the truncated many-body space. We therefore seek to improve the accuracy obtained for a given basis size by optimizing the choice of single-particle orbitals. Natural orbitals, which diagonalize the one-body density matrix, provide a basis which maximizes the occupation of low-lying orbitals, thus accelerating convergence in a configuration-interaction basis, while also possibly providing physical insight into the single-particle structure of the many-body wave function. We describe the implementation of natural orbitals in the NCCI framework, and examine the nature of the natural orbitals thus obtained, the properties of the resulting many-body wave functions, and the convergence of observables. After taking $^{3} He$ as an illustrative testbed, we explore aspects of NCCI calculations with natural orbitals for the ground state of the $p$ -shell neutron halo nucleus $^{6} He$ .
Comments:
26 pages, 17 figures
Subjects:
Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2112.04027 [pdf]
PRC(2022)·20 citations
02
[Submitted on 8 Dec 2021]
Symmetry and shape coexistence in 10Be
M. A. Caprio · A. E. McCoy · P. J. Fasano · T. Dytrych
Within the low-lying spectrum of 10Be, multiple rotational bands are found, with strikingly different moments of inertia. A proposed interpretation has been that these bands variously represent triaxial rotation and prolate axially-deformed rotation. The bands are well-reproduced in ab initio no-core configuration interaction (NCCI) calculations. We use the calculated wave functions to elucidate the nuclear shapes underlying these bands, by examining the Elliott SU(3) symmetry content of these wave functions. The ab initio results support an interpretation in which the ground-state band, along with an accompanying K=2 side band, represent a triaxial rotor, arising from an SU(3) irreducible representation in the 0 hbar omega space. Then, the lowest excited K=0 band represents a prolate rotor, arising from an SU(3) irreducible representation in the 2 hbar omega space.
Comments:
10 pages, 4 figures; contribution to the proceedings of the International Workshop "Shapes and Dynamics of Atomic Nuclei: Contemporary Aspects" (SDANCA-21), Sofia, Bulgaria, September 2021; submitted to Bulg. J. Phys
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2112.04056 [pdf]
Bulg.J.Phys.(2022)·10 citations
03
[Submitted on 8 Dec 2021]
Translating neutron star observations to nuclear symmetry energy via artificial neural networks
Plamen G. Krastev (Harvard University)
One of the most significant challenges involved in efforts to understand the equation of state of dense neutron-rich matter is the uncertain density dependence of the nuclear symmetry energy. Because of its broad impact, pinning down the density dependence of the nuclear symmetry energy has been a longstanding goal of both nuclear physics and astrophysics. Recent observations of neutron stars, in both electromagnetic and gravitational-wave spectra, have already constrained significantly the nuclear symmetry energy at high densities. Training deep neural networks to learn a computationally efficient representation of the mapping between astrophysical observables of neutron stars, such as masses, radii, and tidal deformabilities, and the nuclear symmetry energy allows its density dependence to be determined reliably and accurately. In this work we use a deep learning approach to determine the nuclear symmetry energy as a function of density directly from observational neutron star data. We show for the first time that artificial neural networks can precisely reconstruct the nuclear symmetry energy from a set of available neutron star observables, such as, masses and radii as those measured by, e.g., the NICER mission, or masses and tidal deformabilities as measured by the LIGO/VIRGO/KAGRA gravitational-wave detectors. These results demonstrate the potential of artificial neural networks to reconstruct the symmetry energy, and the equation of state, directly from neutron star observational data, and emphasize the importance of the deep learning approach in the era of Multi-Messenger Astrophysics.
Comments:
16 pages, 6 figures. Invited article for Galaxies for the Special Issue "Neutron Stars and Hadrons in the Era of Gravitational Wave Astrophysics". Published version
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
arXiv:
2112.04089 [pdf]
Galaxies(2022)·35 citations
04
[Submitted on 8 Dec 2021]
Thermal properties of hot and dense medium in interacting hadron resonance gas model
S. Sahoo🇮🇳 · D. K. Mishra🇮🇳 · P. K. Sahu🇮🇳
The meson exchange interaction based on relativistic mean-field (RMF) theory has been introduced in the hadron resonance gas (HRG) model, called interacting HRG (iHRG) model. This model can be used to explain the experimental data both at finite temperature ( $T$ ) with finite chemical potential ( $μ_{B}$ ) and finite temperature at vanishing chemical potential. The nuclear matter equation of state also can be explained at zero temperature with finite baryon density (finite chemical potential) due to the presence of attractive and repulsive interactions between the hadrons in the iHRG model. Similarly, the lattice equation of state is well described at $μ_{B}$ = 0 and finite temperature by the iHRG model. In the present study, we have calculated the thermodynamical quantities as a function of temperature and chemical potential using both HRG and iHRG models. Also, we have presented the isothermal compressibility ( $k_{T}$ ), specific heat ( $C_{V}$ ), and speed of sound ( $c_{s}^{2}$ ) as a function of $μ_{B}$ , $T$ , and center of mass energies. The effect of kinematic acceptance on these quantities are also presented as a function of $μ$ and $T$ . Results from this study on $k_{T}$ are compared with results from other heavy-ion transport models and experimental data up to LHC energies.
Comments:
34 pages, 16 figures, accepted for publication in Nuclear Physics A
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2112.04117 [pdf]
NPA(2022)·4 citations
05
[Submitted on 8 Dec 2021]
Band-like structures and quartets in deformed N=Z nuclei
M. Sambataro · N. Sandulescu
We provide a description of deformed $N = Z$ nuclei in a formalism of $α$ -like quartets. Quartets are constructed variationally by resorting to the use of proper intrinsic states. Various types of intrinsic states are introduced which generate different sets of quartets for a given nucleus. Energy spectra are generated via configuration-iteraction calculations in the spaces built with these quartets. The approach has been applied to $^{24}$ Mg and $^{28}$ Si in the $s d$ shell and to $^{48}$ Cr in the $p f$ shell. In all cases a good description of the low-lying spectra has been achieved. As a peculiarity of the approach, a close correspondence is observed between the various sets of quartets employed and the occurrence of well defined band-like structures in the spectra of the systems under study.
Comments:
16 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2112.04370 [pdf]
PLB(2022)·7 citations
06
[Submitted on 7 Dec 2021] (cross-list from hep-ph)
Quantum Simulation of Chiral Phase Transitions
Alexander M. Czajka🇺🇸 · Zhong-Bo Kang🇺🇸 · Henry Ma🇺🇸 · Fanyi Zhao🇺🇸
The Nambu-Jona-Lasinio (NJL) model has been widely studied for investigating the chiral phase structure of strongly interacting matter. The study of the thermodynamics of field theories within the framework of Lattice Field Theory is limited by the sign problem, which prevents Monte Carlo evaluation of the functional integral at a finite chemical potential. Using the quantum imaginary time evolution (QITE) algorithm, we construct a quantum simulation for the $(1 + 1)$ dimensional NJL model at finite temperature and finite chemical potential. We observe consistency among digital quantum simulation, exact diagonalization, and analytical solution, indicating further applications of quantum computing in simulating QCD thermodynamics.
Comments:
25 pages, 6 figures, published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2112.03944 [pdf]
JHEP(2022)·40 citations
07
[Submitted on 7 Dec 2021] (cross-list from hep-lat)
$x$ -dependence reconstruction of pion and kaon PDFs from Mellin moments
Constantia Alexandrou🇨🇾 · Simone Bacchio🇨🇾 · Ian Cloët🇺🇸 · Martha Constantinou🇺🇸 · Kyriakos Hadjiyiannakou🇨🇾 · Giannis Koutsou🇨🇾 · Colin Lauer🇺🇸
We present a calculation of the connected-diagram contributions to the first three non-trivial Mellin moments for the pion and kaon, extracted using local operators with up to 3 covariant derivatives. We use one ensemble of gauge configurations with two degenerate light, a strange and a charm quark ( $N_{f}$ =2+1+1) of maximally twisted mass fermions with clover improvement. The ensemble has a pion mass $\sim$ 260 MeV, and a kaon mass $\sim$ 530 MeV. We reconstruct the $x$ -dependence of the PDFs via fits to our results, and find that our lattice data favor a $(1 - x)^{2}$ -behavior in the large- $x$ region for both the pion and kaon PDFs. We integrate the reconstructed PDFs to extract the higher moments, $⟨ x^{n} ⟩$ , with $4 \leq n \leq 6$ . Finally, we compare the pion and kaon PDFs, as well as the ratios of their Mellin moments, to address the effect of SU(3) flavor symmetry breaking.
Comments:
11 pages, 5 figures, Proceedings of the 38th Annual International Symposium on Lattice Field Theory - LATTICE2021
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2112.03952 [pdf]
PoS(2022)·2 citations
08
[Submitted on 7 Dec 2021] (cross-list from hep-lat)
Pion and kaon form factors using twisted-mass fermions
Constantia Alexandrou🇨🇾 · Simone Bacchio🇨🇾 · Ian Cloët🇺🇸 · Martha Constantinou🇺🇸 · Joseph Delmar🇺🇸 · Kyriakos Hadjiyiannakou🇨🇾 · Giannis Koutsou🇨🇾 · Colin Lauer🇺🇸 · Alejandro Vaquero Avilés-Casco🇺🇸
We present a calculation of the scalar, vector and tensor pion and kaon form factors using one ensemble of two degenerate light, a strange and a charm quark ( $N_{f} = 2 + 1 + 1$ ) of maximally twisted mass fermions with clover improvement. The quark masses are chosen so that they produce a pion mass of about 265 MeV, and a kaon mass of 530 MeV. The lattice spacing of the ensemble is 0.093 fm and the lattice has a spatial extent of 3 fm. We use a rest frame, as well as a boosted frame to obtain the form factors for a wider and denser set of four-vector momentum transfer squared, $Q^{2}$ . To assess and eliminate excited-states contamination, we analyze several values of the source-sink time separation within the range of 1.12 - 2.23 fm (1.12 - 1.67 fm) for the rest (boosted) frame. The $Q^{2}$ dependence of the form factors is parametrized using a monopole fit, which leads to the extraction of the corresponding radius, and the tensor anomalous magnetic moment for the tensor form factor. The results for these parametrizations are compared for the pion and kaon to assess the level of the SU(3) flavor symmetry breaking.
Comments:
10 pages, 6 figures, Proceedings of the 38th Annual International Symposium on Lattice Field Theory - LATTICE2021
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2112.03953 [pdf]
PoS(2022)·1 citation
09
[Submitted on 8 Dec 2021] (cross-list from hep-ph)
Radiative decay of the $Ξ_{c} (2923)$ in a hadronic molecule picture
Feng Yang🇨🇳 · Hong Qiang Zhu🇨🇳 · Yin Huang🇰🇷
In the present work, we study the radiative decay of newly observed $Ξ_{c} (2923)^{0}$ based on the successful explanation that $Ξ_{c} (2923)^{0}$ is an $S$ -wave $D Λ - D Σ$ molecular state in our previous study~\cite{Zhu:2020jke}. The radiative decay width of $D Λ - D Σ$ molecular state into $Ξ_{c}^{0} γ$ final state through hadronic loops are evaluated using effective Lagrangians. We find that decay width $Ξ_{c} (2923)^{0} \to Ξ_{c}^{0} γ$ and $Ξ_{c} (2923)^{0} \to Ξ_{c}^{^{'} 0} γ$ is evaluated to be approximately 1.23-11.66 KeV and 0.30-3.71 KeV, respectively. These are different from the results~\cite{Wang:2020gkn,Bijker:2020tns} that obtained by assuming $Ξ_{c} (2923)^{0}$ may be conventional charmed baryon. If measurements are in future experimental, these differences will be very useful to help us to test various interpretations of $Ξ_{c} (2923)^{0}$ .
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2112.04130 [pdf]
1 citation
10
[Submitted on 8 Dec 2021] (cross-list from hep-ph)
Tetraquarks: relativistic corrections and other issues
Jean-Marc Richard🇫🇷 · Alfredo Valcarce🇪🇸 · Javier Vijande🇪🇸
We discuss the effect of relativistic kinematics on the binding energy of multiquark states. For a given potential, the use of relativistic kinematics lowers the energy by a larger amount for the threshold made of two mesons than for a tetraquark, so that its binding is weakened. Some other issues associated with exotic hadrons are also briefly discussed.
Comments:
7 pages, 2 figures, Contribution to Hadron 2021 (19th International Conference on Hadron Spectroscopy and Structure in memoriam Simon Eidelman), Mexico City, 26-31 July 2021, to appear in the Proceedings (Suplemento de la Revista Mexicana de Fisica). Version 2: changes in the format of bibliography
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2112.04300 [pdf]
Rev.Mex.Fis.Suppl.(2022)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE