Nuclear Theory·nucl-th

Wednesday·September 5, 2018

23 papers—13 primary·10 cross-listed

01
[Submitted on 31 Aug 2018]
Stability of the neutron-proton-electron matter under strong magnetic fields: the covariant Vlasov approach
Sidney Avancini · B. P. Bertolino · Aziz Rabhi · Jianjun Fang · Helena Pais · Constança Providência
The neutron-proton-electron(npe) matter under a strong magnetic field is studied in the context of the covariant Vlasov approach. We use a Walecka-type hadronic model and the dispersion relations for the longitudinal and transverse modes are obtained. The instability regions for longitudinal and transverse modes are also studied. The crust-core transition of a magnetized neutron star is discussed.
Comments:
14pages, 4 figures, accepted for publication in PRC
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1809.00061 [pdf]
PRC(2018)·9 citations
02
[Submitted on 1 Sept 2018]
Bubble Structure in Magic Nuclei
G. Saxena🇮🇳 · M. Kumawat🇮🇳 · M. Kaushik · S. K. Jain🇮🇳 · Mamta Aggarwal🇮🇳
The existence of bubble nuclei identified by the central depletion in nucleonic density is studied for the conventional magic N (Z) $=$ 8, 20, 28, 40, 50, 82, 126 isotones (isotopes) and recently speculated magic N $=$ 164, 184, 228 superheavy isotones. Many new bubble nuclei are predicted in all regions. Study of density profiles, form factor, single particle levels and depletion fraction (DF) across the periodic chart reveals that the central depletion is correlated to shell structure and occurs due to unoccupancy in s-orbit (2s, 3s, 4s) and inversion of (2s, 1d) and (3s, 1h) states in nuclei upto Z $\leq$ 82. Bubble effect in superheavy region is a signature of the interplay between the Coulomb and nn-interaction and depletion fraction (DF) is found to increase with Z (Coulomb repulsion) and decrease with isospin. Our results are consistent with the available data. The occupancy in s-state in $^{34}$ Si increases with temperature which appears to quench the bubble effect.
Comments:
7 pages, 8 figures, Accepted, Physics Letters B, 2018
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1809.00099 [pdf]
PLB(2019)·46 citations
03
[Submitted on 1 Sept 2018]
Unitary limit and linear scaling of neutrons in harmonic trap with tuned CD-Bonn and square-well interactions
Yi-Yuan Cheng🇨🇳 · Thomas T. S. Kuo🇺🇸 · Ruprecht Machleidt🇺🇸 · Yu-Min Zhao🇨🇳
We study systems of finite-number neutrons in a harmonic trap at the unitary limit. Two very different types of neutron-neutron interactions are applied, namely, the meson-theoretic CD-Bonn potential and hard-core square-well interactions, all tuned to possess infinite scattering lengths, and with effective ranges comparable to or larger than the trap size. The potentials are renormalized to equivalent, scattering-length preserving low-momentum potentials, $V_{low - k}$ , with which the particle-particle hole-hole ring diagrams are summed to all orders to yield the ground-state energy $E_{0}$ of the finite neutron system. We find the ratio $E_{0} / E_{0}^{free}$ (where $E_{0}^{free}$ denotes the ground-state energy of the corresponding non-interacting system) to be remarkably independent from variations of the harmonic trap parameter, the number of neutrons, the decimation momentum of $V_{low - k}$ , and the type and effective range of the unitarity potential. Our results support a special virial linear scaling relation of $E_{0}$ . Certain properties of Landau's quasi-particles for trapped neutrons at the unitary limit are also discussed.
Comments:
7 pages, 3 figures, 1 table
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.00205 [pdf]
PLB(2019)·4 citations
04
[Submitted on 2 Sept 2018]
Effective operators in two-nucleon systems
James P. Vary🇺🇸 · Robert Basili🇺🇸 · Weijie Du🇺🇸 · Matthew Lockner🇺🇸 · Pieter Maris🇺🇸 · Soham Pal🇺🇸 · Shiplu Sarker🇺🇸
Effective Hamiltonians and effective electroweak operators are calculated with the Okubo-Lee-Suzuki formalism for two-nucleon systems. Working within a harmonic oscillator basis, first without and then with a confining harmonic oscillator trap, we demonstrate the effects of renormalization on observables calculated for truncated basis spaces. We illustrate the renormalization effects for the root-mean-square point-proton radius, electric quadrupole moment, magnetic dipole moment, Gamow-Teller transition and neutrinoless double-beta decay operator using nucleon-nucleon interactions from chiral Effective Field Theory. Renormalization effects tend to be larger in the weaker traps and smaller basis spaces suggesting applications to heavier nuclei with transitions dominated by weakly-bound nucleons would be subject to more significant renormalization effects within achievable basis spaces.
Comments:
19 pages, 5 figures, Appendix with 4 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.00276 [pdf]
PRC(2018)·11 citations
05
[Submitted on 2 Sept 2018]
Complete experiments in pseudoscalar meson photoproduction revisited
K. Nakayama🇺🇸
By exploiting the underlying symmetries of the relative phases of the pseudoscalar meson photoproduction amplitude, we determine all the possible sets of four double-spin observables that resolve the phase ambiguity of the amplitude in transversity basis up to an overall phase. The present results corroborate the original findings by Chiang and Tabakin [Phys. Rev. C 55, 2054 (1997)]. However, it is found that the completeness condition of four double-spin observables to resolve the phase ambiguity holds only when the relative phases do not meet the condition of equal magnitudes. In situations where this condition occurs, it is shown that one needs extra chosen observables, resulting in the minimum number of observables required to resolve the phase ambiguity to reach up to eight, depending on the particular set of four double-spin observables considered. Furthermore, a way of gauging when the condition of equal magnitudes occurs is provided.
Comments:
Title changed, typos corrected, references added
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1809.00335 [pdf]
PRC(2019)·12 citations
06
[Submitted on 3 Sept 2018]
Stability of alpha-chain States against Break-up and Binary Disintegrations
Akihiro Tohsaki🇯🇵 · Naoyuki Itagaki🇯🇵
We focus upon the raison d'etre of the alpha-chain states on the basis of the fully microscopic framework, where the Pauli principle among all the nucleons is fully taken into account. Our purpose is to find out the limiting number of alpha clusters, on which the linear alpha-cluster state can stably exist. How many alpha-clusters can stably make an alpha-chain state? We examine the properties of equally separated alpha clusters on a straight line and compare its stability with that on a circle. We also confirm its stability in terms of break-up and binary disintegrations including alpha-decay and fission modes. For the effective nucleon-nucleon interaction, we employ the F1 force, which has finite-range three-body terms and guarantees overall saturation properties of nuclei. This interaction also gives reasonable binding energy and size of the alpha particle and the alpha-alpha scattering phase shift. The result astonishes us because we can point out a possible existence of alpha-chain states with vast numbers of alpha clusters.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.00460 [pdf]
PTEP(2019)·3 citations
07
[Submitted on 3 Sept 2018]
The Self-energy of Nucleon for the Anomalous Magnetic Moment
Susumu Kinpara🇯🇵
The anomalous part of the magnetic moment of nucleon is studied. The electromagnetic vertex of nucleon is calculated using the pseudovector coupling pion-nucleon interaction. The self-energy of nucleon suggested in the previous study is applied to the internal line.
Comments:
9 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.00475 [pdf]
2 citations
08
[Submitted on 3 Sept 2018]
Effect of Confinement of Gluons and One Pion Exchange in Nucleon-Nucleon Interaction
V K Nilakanthan🇮🇳 · V C Shastry🇮🇳 · S Raghavendra🇮🇳 · K B Vijaya Kumar🇮🇳
The Nucleon-Nucleon interaction in the singlet ( $^{1} S_{0}$ ) and triplet ( $^{3} S_{1}$ ) channels have been studied in the framework of Relativistic Harmonic Model using the Resonating Group Method in Born-Oppenheimer approximation. The full Hamiltonian consists of the kinetic energy, two body confinement potential, confined one gluon exchange potential and one pion exchange potential. Contribution of Confined One Gluon Exchange Potential and One Pion Exchange Potential to the adiabatic nucleon-nucleon interaction potential is discussed.
Comments:
8 pages, 6 figures; Text expanded and rewritten, Title edited to better suit the text
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1809.00539 [pdf]
Eur.Phys.J.Plus(2019)·3 citations
09
[Submitted on 3 Sept 2018]
Effective Field Theory in The Study of Long Range Nuclear Parity Violation on Lattice
Feng-Kun Guo🇨🇳 · Chien-Yeah Seng🇨🇳
A non-zero signal $A_{γ}^{np} = (- 3.0 \pm 1.4 \pm 0.2) \times 1 0^{- 8}$ of the gamma-ray asymmetry in the neutron-proton capture was recently reported by the NPDGamma Collaboration which provides the first determination of the $Δ I = 1$ parity-odd pion-nucleon coupling constant $h_{π}^{1} = (2.6 \pm 1.2 \pm 0.2) \times 1 0^{- 7}$ . The ability to reproduce this value from first principles serves as a direct test of our current understanding of the interplay between the strong and weak interaction at low energy. To motivate new lattice studies of $h_{π}^{1}$ , we review the current status of the theoretical understanding of this coupling, which includes our recent work that relates it to a nucleon mass-splitting by a soft-pion theorem. We further investigate the possibility of calculating the mass-splitting on the lattice by providing effective field theory parameterizations of all the involved quark contraction diagrams. We show that the lattice calculations of the easier connected diagrams will provide information of the chiral logarithms in the much harder quark loop diagrams and thus help in the chiral extrapolation of the latter.
Comments:
43 pages, 3 figures, 1 table. Accepted by EPJC
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1809.00639 [pdf]
EPJC(2019)·12 citations
10
[Submitted on 3 Sept 2018]
Isolating dynamical net-charge fluctuations
Rudolph Rogly🇫🇷 · Giuliano Giacalone🇫🇷 · Jean-Yves Ollitrault🇫🇷
We modify the usual definitions of cumulants of net-charge fluctuations in a way that isolates dynamical fluctuations. The new observables, which we call dynamical cumulants, are robust with respect to trivial correlations induced by volume fluctuations and global charge conservation. We illustrate the potential of dynamical cumulants by carrying out Monte Carlo simulations where all correlations are trivial. The results of our simulations agree well with Relativistic Heavy Ion Collider (RHIC) data, and are used to illustrate that dynamical cumulants consistently isolate dynamical fluctuations.
Comments:
9 pages; 3 figures; v2: Sec. V added on the effects of resonance decays
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1809.00648 [pdf]
PRC(2019)·9 citations
11
[Submitted on 3 Sept 2018]
Asymmetry of the neutrino mean free path in hot neutron matter under strong magnetic fields
Julio Torres Patiño🇦🇷 · Eduardo Bauer🇦🇷 · Isaac Vidaña🇮🇹
The neutrino mean free path in neutron matter under a strong magnetic field is evaluated for the inelastic scattering reaction and studied as a function of the neutron matter density in the range $0.05 \leq ρ \leq 0.4$ fm $^{- 3}$ for several temperatures up to 30 MeV and magnetic field strengths B=0 G, $1 0^{18}$ G and $2.5 \times 1 0^{18}$ G. Polarized neutron matter is described within the non--relativistic Brueckner--Hartree--Fock (BHF) approach using the Argonne V18 nucleon-nucleon potential supplemented with the Urbana IX three-nucleon force. Explicit expressions of the cross section per unit volume for the scattering of a neutrino with a spin up or spin down neutron are derived from the Fermi Golden rule. Our results show that the mean free path depends strongly on the angle of the incoming neutrino, leading to an asymmetry in this quantity. This asymmetry depends on the magnetic field intensity and on the density, but it is rather independent of the temperature. For a density of $0.16$ fm $^{- 3}$ at a temperature T $= 30$ MeV, the asymmetry in the mean free path is found to be of $\sim 15%$ for B= $1 0^{18}$ G and $\sim 38%$ for B= $2.5 \times 1 0^{18}$ G.
Comments:
32 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.00688 [pdf]
PRC(2019)·9 citations
12
[Submitted on 31 Aug 2018]
Electromagnetic and weak decays of baryons in the unquenched quark model
Roelof Bijker🇲🇽 · Gustavo Guerrero-Navarro🇲🇽 · Emmanuel Ortiz-Pacheco🇲🇽
In this contribution, we discuss the electromagnetic and weak decays of baryons in the unquenched quark model and show that the observed discrepancies between the experimental data and the predictions of the constituent quark model can be accounted for in large part by the effects of sea quarks. Finally, the obtained results are discussed in terms of flavor-symmetry breaking.
Comments:
5 pages, 3 tables, XLI Symposium on Nuclear Physics, Cocoyoc, Mexico, 2018. arXiv admin note: substantial text overlap with arXiv:1712.03919
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1809.01014 [pdf]
J.Phys.Conf.Ser.(2018)·0 citations
13
[Submitted on 4 Sept 2018]
Individual low-energy E1 toroidal and compression states in light nuclei: deformation effect, spectroscopy and interpretation
V.O. Nesterenko🇷🇺 · J. Kvasil🇨🇿 · A. Repko🇸🇰 · P.-G. Reinhard🇩🇪
The existence of individual low-energy E1 toroidal and compression states (TS and CS) in $^{24}$ Mg was predicted recently in the framework of quasiparticle random-phase-approximation (QRPA) model with Skyrme forces. It was shown that the strong axial deformation of $^{24}$ Mg is crucial to downshift the toroidal strength to the low-energy region and thus make the TS the lowest E1(K=1) dipole state. In this study, we explain this result by simple mean-field arguments. Comparing TS in two strongly axial nuclei, $^{24}$ Mg and $^{20}$ Ne, we show that the lowest TS is not not a universal phenomenon but rather a peculiarity of $^{24}$ Mg. The spectroscopy of TS and CS is analyzed and some additional interpretation of these states is suggested.
Comments:
6 pages, 8 figures, 2 tables. Submitted to proceedings of International Conference on Nuclear Structure and Related Topics - NSRT18 (Bulgaria, Bourgas, June 3-9, 2018). The paper was resubmitted to enlarge the reference list
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.01097 [pdf]
EPJ Web Conf.(2018)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE