Nuclear Theory·nucl-th

Monday·May 10, 2021

15 papers—5 primary·10 cross-listed

01
[Submitted on 7 May 2021]
Drastic change in inelastic scattering depending on the development of dineutron correlation in $^{10}$ Be
T. Furumoto · T. Suhara · N. Itagaki
We investigated the development and breaking of the dineutron correlation in $^{10}$ Be by analyzing the elastic and inelastic scatterings with a framework combing the microscopic structure and reaction models. For studying the structure, the $^{10}$ Be nucleus was constructed under the assumption of a four-body ( $α + α + n + n$ ) cluster model. In this work, we focused on the change in the inner structure for the 0 $_{1}^{+}$ , 2 $_{1}^{+}$ , and 2 $_{2}^{+}$ states when the strength of the spin-orbit interaction is varied. The inner structure, including various physical quantities such as energy, radius, and transition strength, is drastically influenced by the strength of the spin-orbit interaction. In particular, the development and breaking of the dineutron correlation is governed by the spin-orbit strength. The differences in the inner structure can be manifested by applying the obtained wave functions to elastic and inelastic scatterings with a proton target at $E / A =$ 59.4 and 200 MeV. Although the 0 $_{1}^{+}$ and 2 $_{1}^{+}$ states are significantly influenced by the spin-orbit strength of the nuclear structure calculation, the elastic and inelastic cross sections are not much affected. On the other hand, the inelastic cross section of the 2 $_{2}^{+}$ state depends greatly on the spin-orbit strength of the structure calculation. Thus, we discovered a way to measure the degree of the development of dineutron cluster structure based on its sensitivity to the inelastic cross section of the 2 $_{2}^{+}$ state of $^{10}$ Be.
Comments:
22 pages, 7 figures, accepted for publication in Physical Review C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2105.03025 [pdf]
PRC(2021)·6 citations
02
[Submitted on 7 May 2021]
Coulomb screening effect on the Hoyle state energy in thermal plasmas
Lai Hnin Phyu · H. Moriya · W. Horiuchi · K. Iida · K. Noda · M. T. Yamashita
The first excited $J^{π} = 0^{+}$ state of $^{12}$ C, the so-called Hoyle state, plays an essential role in a triple- $α$ ( $^{4}$ He) reaction, which is a main contributor to the synthesis of $^{12}$ C in a burning star. We investigate the Coulomb screening effects on the energy shift of the Hoyle state in a thermal plasma environment using precise three- $α$ model calculations. The Coulomb screening effect between $α$ clusters are taken into account within the Debye-Hückel approximation. To generalize our study, we utilize two standard $α$ -cluster models, which treat the Pauli principle between the $α$ particles differently. We find that the energy shifts do not depend on these models and follow a simple estimation in the zero-size limit of the Hoyle state when the Coulomb screening length is as large as a value typical of such a plasma consisting of electrons and $α$ particles.
Comments:
6 pages, 2 figures, contribution to the 8th Asia-Pacific Conference on Few-Body Problems in Physics (APFB2020), 1-5 March 2021, Kanazawa, Japan
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2105.03031 [pdf]
Few Body Syst.(2021)·2 citations
03
[Submitted on 7 May 2021]
Pairing and nonaxial-shape correlations in $N = 150$ isotones
Kenichi Yoshida🇯🇵
Background: The $K^{π} = 2^{-}$ excited band emerges systematically in $N = 150$ isotones raging from Pu to No with even- $Z$ numbers, and a sharp drop in energies was observed in Cf. Purpose: I attempt to uncover the microscopic mechanism for the appearance of such a low-energy $2^{-}$ state in $^{248}$ Cf. Furthermore, I investigate the possible occurrence of the low-energy $K^{π} = 2^{+}$ state to elucidate the mechanism that prefers the simultaneous breaking of the reflection and axial symmetry to the breaking of the axial symmetry alone in this mass region. Method: I employ a nuclear EDF method: the Skyrme-Kohn-Sham-Bogoliubov and the quasiparticle random-phase approximation are used to describe the ground state and the transition to excited states. Results: The Skyrme-type SkM* and SLy4 functionals reproduce the fall in energy, but not the absolute value, of the $K^{π} = 2^{-}$ state at $Z = 98$ , where the proton 2qp excitation $[633] 7/2 \otimes [521] 3/2$ plays a decisive role for the peculiar isotonic dependence. I find interweaving roles by the pairing correlation of protons and the deformed shell closure at $Z = 98$ . The SkM* model predicts the $K^{π} = 2^{-}$ state appears lower in energy in $^{246}$ Cf than in $^{248}$ Cf as the Fermi level of neutrons is located in between the $[622] 5/2$ and $[734] 9/2$ orbitals. Except for $^{250}$ Fm in the SkM* calculation, the $K^{π} = 2^{+}$ state is predicted to appear higher in energy than the $K^{π} = 2^{-}$ state because the quasi-proton $[521] 1/2$ orbital is located above the $[633] 7/2$ orbital. Conclusions: A systematic study of low-lying collective states in heavy actinide nuclei provides a rigorous testing ground for microscopic nuclear models. The present study shows a need for improvements in the EDFs to describe pairing correlations and shell structures in heavy nuclei, that are indispensable in predicting the heaviest nuclei.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2105.03128 [pdf]
PRC(2021)·5 citations
04
[Submitted on 18 Apr 2021]
Limits on active-sterile neutrino mixing parameters using heavy nuclei abundances
M. M. Saez🇦🇷 · K. J. Fushimi🇦🇷 · M. E. Mosquera🇦🇷 · O. Civitarese🇦🇷
The production of heavy-mass elements due to the rapid neutron-capture mechanism (r-process) is associated with astrophysical scenarios, such as supernovae and neutron-star mergers. In the r-process the capture of neutrons is followed by $β$ -decays until nuclear stability is reached. A key element in the chain of nuclear weak-decays leading to the production of isotopes may be the change of the parameters controlling the neutrino sector, due to the mixing of active and sterile species. In this work we have addressed this question and calculated $β$ -decay rates for the nuclei involved in the r-process chains as a function of the neutrino mixing parameters. These rates were then used in the calculation of the abundance of the heavy elements produced in core-collapse supernova and in neutron-star mergers, starting from different initial mass-fraction distributions. The analysis shows that the core-collapse supernova environment contributes with approximately $30%$ of the total heavy nuclei abundance while the neutron-star merger contributes with about $70%$ of it. Using available experimental data we have performed a statistical analysis to set limits on the active-sterile neutrino mixing angle and found a best-fit value $sin^{2} 2 θ_{14} = 0.22$ , a value comparable with those found in other studies reported in the literature.
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2105.03202 [pdf]
IJMPE(2021)·1 citation
05
[Submitted on 7 May 2021]
Fluctuations in the pasta phase
Mateus R. Pelicer🇧🇷 · Débora P. Menezes🇧🇷 · Celso C. Barros Jr🇧🇷 · Francesca Gulminelli🇫🇷
Baryonic matter close to the saturation density is very likely to present complex inhomogeneous structures collectively known under the name of pasta phase. At finite temperature, the different geometric structures are expected to coexist, with potential consequences on the neutron star crust conductivity and neutrino transport in supernova matter. In the framework of a statistical multi-component approach, we calculate the composition of matter in the pasta phase considering density, proton fraction, and geometry fluctuations. Using a realistic energy functional from relativistic mean field theory and a temperature and isospin dependent surface tension fitted from Thomas-Fermi calculations, we show that different geometries can coexist in a large fraction of the pasta phase, down to temperatures of the order of the crystallization temperature of the neutron star crust. Quantitative estimates of the charge fluctuations are given.
Comments:
6 pages, 3 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2105.03318 [pdf]
PRC(2021)·9 citations
06
[Submitted on 6 May 2021] (cross-list from quant-ph)
A digital quantum simulation of the Agassi model
Pedro Pérez-Fernández🇪🇸 · José Miguel Arias🇪🇸 · José Enrique García-Ramos🇪🇸 · Lucas Lamata🇪🇸
A digital quantum simulation of the Agassi model from nuclear physics is proposed and analyzed. The proposal is worked out for the case with four different sites. Numerical simulations and analytical estimations are presented to illustrate the feasibility of this proposal with current technology. The proposed approach is fully scalable to a larger number of sites. The use of a quantum correlation function as a probe to explore the quantum phases by quantum simulating the time dynamics, with no need of computing the ground state, is also studied. Evidence is given showing that the amplitude of the time dynamics of a correlation function in this quantum simulation is linked to the different quantum phases of the system. This approach establishes an avenue for the digital quantum simulation of useful models in nuclear physics.
Comments:
8 pages, 5 figures. Improved manuscript. Published in PLB
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
arXiv:
2105.02834 [pdf]
PLB(2022)·20 citations
07
[Submitted on 6 May 2021] (cross-list from physics.comp-ph)
On the numerical evaluation of real-time path integrals: Double exponential integration and the Maslov correction
R. Rosenfelder🇨🇭
Ooura's double exponential integration formula for Fourier transforms is applied to the oscillatory integrals occuring in the path-integral description of real-time Quantum Mechanics. Due to an inherent, implicit regularization multi-dimensional Gauss-Fresnel integrals are obtained numerically with high precision but modest number of function calls. In addition, the Maslov correction for the harmonic oscillator is evaluated numerically with an increasing number of time slices in the path integral thereby clearly demonstrating that the real-time propagator acquires an additional phase $- π /2$ each time the particle passes through a focal point. However, in the vicinity of these singularities an overall small damping factor is required. Prospects of evaluating scattering amplitudes of finite-range potentials by direct numerical evaluation of a real-time path integral are discussed.
Comments:
21 pages, 7 figures, 2 tables, LATEX with amsmath,amssymb
Subjects:
Computational Physics (physics.comp-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2105.02880 [pdf]
0 citations
08
[Submitted on 6 May 2021] (cross-list from astro-ph.HE)
Impact of PREX-II and combined Radio/NICER/XMM-Newton's mass-radius measurement of PSRJ0740+6620 on the dense matter equation of state
Bhaskar Biswas🇮🇳
In this paper, we discuss the impact of the following laboratory experiments and astrophysical observation of neutron stars (NSs) on its equation of state (EoS): (a) The new measurement of neutron skin thickness of $^{208} Pb$ , $R_{skin}^{208} = 0.29 \pm 0.07$ fm by the PREX-II experiment. (b) The mass measurement of PSR J0740+6620 has been slightly revised down by including additional $\sim 1.5$ years of pulsar timing data. As well as the radius measurement of PSR J0740+6620 by joint NICER/XMM-Newton collaboration which has a similar size to PSR J0030+0451. We combine these information using Bayesian statistics along with the previous LIGO/Virgo and NICER observations of NS using a hybrid nuclear+piecewise polytrope (PP) EoS parameterization. Our findings are as follows: (a). Adding PREX-II result yields the value of empirical parameter $L = 6 9_{- 19}^{+ 21}$ MeV, $R_{skin}^{208} = 0.2 0_{- 0.05}^{+ 0.05}$ fm, and radius of a $1.4 M_{⊙}$ ( $R_{1.4}) = 12.7 5_{- 0.54}^{+ 0.42}$ km at $1 σ$ confidence interval (CI). We find these inferred values are mostly dominated by the combined astrophysical observations as the measurement uncertainty in $R_{skin}^{208}$ by PREX-II is much broader. Also, a better measurement of $R_{skin}^{208}$ might have a little effect on the radius of low mass NSs, but for the high masses there will be almost no effect. (b) After adding The revised mass and radius measurement of PSR J0740+6620, we find the inferred radius of NSs is slightly pushed towards the larger values and the uncertainty on the radius of a $2.08 M_{⊙}$ NS is moderately improved.
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2105.02886 [pdf]
ApJ(2021)·95 citations
09
[Submitted on 6 May 2021] (cross-list from hep-ph)
Mass spectra and transition magnetic moments of low lying charmed baryons in a quark model
Zahra Ghalenovi🇮🇷 · Masoumeh Moazzen Sorkhi🇮🇷
Excited state mass spectra of the low lying single charmed baryons with non strangeness have been calculated in a hypercentral approach. The six-dimensional hyperradial Schrödinger equation is solved by applying a simple variational method. We extend our scheme to predict the magnetic moments and the $\frac{3}{2}^{+} \to \frac{1}{2}^{+}$ transition magnetic moments of $Σ_{c}$ and $Λ_{c}$ state baryons. A comparison of our results with the experimental data and predictions obtained in recent models is also presented.
Comments:
arXiv admin note: text overlap with arXiv:1707.01319
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2105.02928 [pdf]
IJMPE(2021)·2 citations
10
[Submitted on 7 May 2021] (cross-list from hep-ph)
Partial wave analysis of $K^{+} N$ scattering and the possibility of pentaquark $Θ^{+} (1540)$
Kook-Jin Kong🇰🇷 · Byung-Geel Yu🇰🇷
Elastic $K^{+} n \to K^{+} n$ and charge exchange $K^{+} n \to K^{0} p$ reactions at low momenta are investigated using the partial wave analysis. Isospin relation gives constrains for the partial $s$ - and $p$ -waves among elastic $K^{+} p$ , $K^{+} n$ and charge exchange $K^{+} n \to K^{0} p$ amplitudes. Two sets of the phase shift for these partial waves in the isoscalar channel are obtained from the fit of experimental data on total and differential cross sections. Polarization observable leads to a good criterion to decide which set is valid. Differential cross section data near $P_{Lab} = 434$ MeV/ $c$ suggests a possibility of a resonance, e.g., the exotic $Θ^{+} (1540)$ baryon around $s ≃$ 1.54GeV.
Comments:
6 pages, 9 figures, 1 table, Proc. APFB 2020 Conf
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2105.03040 [pdf]
Few Body Syst.(2021)·2 citations
11
[Submitted on 7 May 2021] (cross-list from hep-ph)
Scalar Mesons and Axial-vector Mesons Via Dyson-Schwinger Equation and Bethe-Salpeter Equation Approach
Muyang Chen🇨🇳
In this work, I studied the spectrum of scalar mesons and axial-vector mesons via Dyson-Schwinger equation and Bethe-Salpeter equation approach in the rainbow-ladder approximation. An interaction model with a repulsive term added to the one used for the pseudoscalar and vector mesons is proposed. My results are consistent with the experiment data and other model results, which shows that this interaction model is effective for all the heavy, heavy-light, and light scalar and axial-vector mesons.
Comments:
5 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2105.03063 [pdf]
1 citation
12
[Submitted on 7 May 2021] (cross-list from hep-ph)
Isospin asymmetry in holographic baryonic matter
Nicolas Kovensky🇬🇧 · Andreas Schmitt🇬🇧
We study baryonic matter with isospin asymmetry, including fully dynamically its interplay with pion condensation. To this end, we employ the holographic Witten-Sakai-Sugimoto model and the so-called homogeneous ansatz for the gauge fields in the bulk to describe baryonic matter. Within the confined geometry and restricting ourselves to the chiral limit, we map out the phase structure in the presence of baryon and isospin chemical potentials, showing that for sufficiently large chemical potentials condensed pions and isospin-asymmetric baryonic matter coexist. We also present first results of the same approach in the deconfined geometry and demonstrate that this case, albeit technically more involved, is better suited for comparisons with and predictions for real-world QCD. Our study lays the ground for future improved holographic studies aiming towards a realistic description of charge neutral, beta-equilibrated matter in compact stars, and also for more refined comparisons with lattice studies at nonzero isospin chemical potential.
Comments:
53 pages, 8 figures, v2: minor improvements in the text, format adapted to SciPost Physics; v3: typos in Eqs.(20) and (30c) corrected
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2105.03218 [pdf]
SciPost Phys.(2021)·35 citations
13
[Submitted on 7 May 2021] (cross-list from hep-ph)
Dalitz plot studies of $D^{0} \to K_{S}^{0} K^{+} K^{-}$ decays in a factorization approach
J.-P.Dedonder🇫🇷 · R. Kamiński🇵🇱 · L. Leśniak🇵🇱 · B. Loiseau🇫🇷
The $BABAR$ Collaboration data of the $D^{0} \to K_{S}^{0} K^{+} K^{-}$ process are analyzed within a quasi two-body factorization framework. In earlier studies, assuming $D^{0}$ transitions to two kaons and the transitions between one kaon and two kaons to proceed through the dominant intermediate resonances, we approximated them as being proportional to the kaon form factors. To obtain good fits, one has to multiply the scalar-kaon form factors, derived from unitary relativistic coupled-channel models or in a dispersion relation approach, by phenomenological energy-dependent functions. The final state kaon-kaon interactions in the $S$ -, $P$ - and $D$ - waves are taken into account. All $S$ -wave channels are treated in a unitary way. The $K^{+} K^{-}$ and $K ˉ^{0} K^{+}$ $S$ -wave effective mass squared distributions, corrected for phase space, are shown, in a model-independent manner, to be significantly different. Then the $f_{0} (980)$ resonance must be included at variance with the BABAR analysis. The best fit has 19 free parameters and indicates i) the dominance of annihilation amplitudes, ii) a large dominance of the $f_{0} (980)$ meson in the near threshold $K^{+} K^{-}$ invariant mass distribution and iii) a sizable branching fraction to the $K_{S}^{0} [ρ (770)^{+} + ρ (1450)^{+} + ρ (1700)^{+}]$ final states. An appendix provides an update of the determination of the isoscalar-scalar meson-meson amplitudes based on an enlarged set of data. A second appendix proposes two alternative fits based on scalar-kaon form factors calculated from the Muskhelishvili-Omnès dispersion relation approach. These fits have $χ^{2}$ quite close to that of the best fit but they show important contributions from both the $f_{0}$ and $a_{0}^{0}$ mesons and a weaker role of the $ρ^{+}$ mesons.
Comments:
50 pages, 17 figures; v2: figure 10 is now cited in the text, typos corrected, matches the published (PRD) version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2105.03355 [pdf]
PRD(2021)·14 citations
14
[Submitted on 7 May 2021] (cross-list from astro-ph.SR)
Effects of Magnetic Fields in Hot White Dwarfs
J. Peterson🇺🇸 · V. Dexheimer🇺🇸 · R. Negreiros🇧🇷 · B. G. Castanheira🇺🇸
In this work, we study the effects of temperature on magnetic white dwarfs. We model their interior as a nuclei lattice surrounded by a relativistic free Fermi gas of electrons, accounting for effects from temperature, Landau levels and anomalous magnetic moment. We find that, at low densities (corresponding to the outer regions of star), both temperature and magnetic field effects play an important role in the calculation of microscopic thermodynamical quantities. To study macroscopic stellar structures within a general-relativistic approach, we solve numerically the coupled Einstein's-Maxwell's equations for fixed entropy per particle configurations and discuss how temperature affects stellar magnetic field profiles, masses and radii.
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2105.03387 [pdf]
ApJ(2021)·17 citations
15
[Submitted on 7 May 2021] (cross-list from hep-ph)
Vector-like Leptons in Light of the Cabibbo-Angle Anomaly
Claudio Andrea Manzari🇨🇭
The first row of the Cabibbo-Cobayashi-Maskawa (CKM) matrix shows a discrepancy of $\sim$ $3 σ$ with unitarity, known as the "Cabibbo Angle Anomaly" (CAA). This tension can be explained via modified $W$ couplings to leptons, but in order to consistently assess the validity of this solution, a global fit including the electroweak (EW) precision constraints and the low energy tests of lepton flavour universality (LFU) is necessary. Performing such a fit for gauge-invariant dimension-6 operators, we find that even when assuming LFU, including the CKM elements $V_{u s}$ and $V_{u d}$ into the electroweak fit has a relevant impact, shifting the best fit point significantly. Vector-like leptons (VLLs) are prime candidates for a corresponding UV completion since they can affect the $W$ and $Z$ couplings to leptons already at tree-level. Studying each pattern of new physics (NP) given by the six possible representations of VLLs (under the SM gauge group) we find that any single representation describes experimental data at most slighlty better than the SM hypothesis. However, allowing for several representations of VLLs at the same time, we find a simple scenario consisting of a singlet, $N$ , coupling to electrons and a triplet, $Σ_{1}$ , coupling to muons which not only explains the CAA but also improves the electroweak fit in such a way that its best fit point is preferred by more than $4 σ$ with respect to the SM.
Comments:
7 pages, 1 figure, 2 tables, contribution to BSM-2021 and the 2021 EW & QCD sessions of the 55th Rencontres de Moriond (shorter version)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2105.03399 [pdf]
7 citations

Affiliations

first authorsco-authorsvia INSPIRE