Nuclear Theory·nucl-th

Monday·October 8, 2018

13 papers—7 primary·6 cross-listed

01
[Submitted on 5 Oct 2018]
Coulomb exchange functional with generalized gradient approximation for self-consistent Skyrme Hartree-Fock calculations
Tomoya Naito · Xavier Roca-Maza · Gianluca Colò · Haozhao Liang
We perform the self-consistent Skyrme Hartree-Fock calculation with the Coulomb exchange functional in the form of generalized gradient approximation (GGA). It is found that the Perdew-Burke-Ernzerhof GGA (PBE-GGA) Coulomb exchange functional is able to reproduce the exact-Fock energy for the nuclei in a large region of the nuclear chart with one adjustable parameter. The remaining error of Coulomb exchange energy by the GGA with respect to the exact-Fock energy dominantly comes from the functional-driven error.
Comments:
22 pages, 6 figures, 3 tables
Subjects:
Nuclear Theory (nucl-th); cond-mat.other (cond-mat.other); Nuclear Experiment (nucl-ex)
arXiv:
1810.02500 [pdf]
PRC(2019)·10 citations
02
[Submitted on 5 Oct 2018]
Cross sections of $α$ -induced reactions slightly below doubly-magic $^{40}$ Ca from the statistical model
P. Mohr · R. Talwar · M. L. Avila
New experimental data for the $^{38}$ Ar( $α$ ,n) $^{41}$ Ca and $^{38}$ Ar( $α$ ,p) $^{41}$ K reactions were used to find a best-fit set of parameters for statistical model calculations. The very good agreement between the experimental data and the best-fit calculation confirms the applicability of the statistical model for nuclei in the vicinity of the doubly-magic $^{40}$ Ca despite of their relatively low level densities. The present study investigates the sensitivities and finds that the $α$ -nucleus and the nucleon-nucleus potentials are the most important ingredients for the calculation of ( $α$ ,n) and ( $α$ ,p) reactions in the statistical model. Furthermore, the width fluctuation correction plays an essential role in the peculiar case of $^{38}$ Ar. The best-fit parameters from $^{38}$ Ar are applied to the mirror nucleus $^{38}$ Ca and the neighboring $^{36}$ Ar and $^{40}$ Ar nuclei. For $^{38}$ Ca this results in an astrophysical reaction rate of the $^{38}$ Ca( $α$ ,p) $^{41}$ Sc reaction which has a flatter temperature dependence compared to all previous calculations. For $^{40}$ Ar a better reproduction of $^{40}$ Ar( $α$ ,p) $^{43}$ K data from literature is obtained. The disagreement between calculation and an early experimental data point for the $^{36}$ Ar( $α$ ,p) $^{39}$ K reaction persists.
Comments:
14 pages, 10 figures; Phys. Rev. C, accepted for publication
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1810.02527 [pdf]
PRC(2018)·4 citations
03
[Submitted on 5 Oct 2018]
Cluster structures in $^{12}$ C from global energy density functionals
Petar Marević🇫🇷 · Jean-Paul Ebran🇫🇷 · Elias Khan🇫🇷 · Tamara Nikšić🇭🇷 · Dario Vretenar🇭🇷
Spectroscopic properties of low-lying states and cluster structures in $^{12}$ C are analyzed in a "beyond mean-field framework" based on global energy density functionals (EDFs). To build symmetry-conserving collective states, axially-symmetric and reflection-asymmetric solutions of the relativistic Hartree-Bogoliubov equations are first projected onto good values of angular momentum, particle number, and parity. Configuration mixing is implemented using the generator coordinate method formalism. It is shown that such a global microscopic approach, based on a relativistic EDF, can account for the main spectroscopic features of $^{12}$ C, including the ground-state and linear-chain bands as well as, to a certain approximation, the excitation energy of the Hoyle state. The calculated form factors reproduce reasonably well the available experimental values, and display an accuracy comparable to that of dedicated microscopic cluster models.
Comments:
10 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1810.02632 [pdf]
PRC(2019)·30 citations
04
[Submitted on 5 Oct 2018]
How (not) to renormalize integral equations with singular potentials in effective field theory
E. Epelbaum🇩🇪 · A. M. Gasparyan🇩🇪 · J. Gegelia🇩🇪 · Ulf-G. Meißner🇩🇪
We discuss the connection between the perturbative and non-perturbative renormalization and related conceptual issues in the few-nucleon sector of the low-energy effective field theory of the strong interactions. General arguments are supported by examples from effective theories with and without pions as dynamical degrees of freedom. A quantum mechanical potential with explicitly specified short- and long-range parts is considered as an "underlying fundamental theory" and the corresponding effective field theory potential is constructed. Further, the problem of the effective field theoretical renormalization of the Skornyakov-Ter-Martyrosian equation is revisited.
Comments:
12 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
arXiv:
1810.02646 [pdf]
EPJA(2018)·71 citations
05
[Submitted on 5 Oct 2018]
Advantages of the multinucleon transfer reactions based on 238U target for producing neutron-rich isotopes around N = 126
Long Zhu · Cheng Li · Jun Su · Chen-Chen Guo · Wei Hua
The mechanism of multinucleon transfer (MNT) reactions for producing neutron-rich heavy nuclei around N = 126 is investigated within two different theoretical frameworks: dinuclear system (DNS) model and isospin-dependent quantum molecular dynamics (IQMD) model. The effects of mass asymmetry relaxation, N=Z equilibration, and shell closures on production cross sections of neutron-rich heavy nuclei are investigated. For the first time, the advantages for producing neutron-rich heavy nuclei around N = 126 is found in MNT reactions based on 238U target. We propose the reactions with 238U target for producing unknown neutron-rich heavy nuclei around N = 126 in the future.
Comments:
6 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1810.02663 [pdf]
PLB(2019)·26 citations
06
[Submitted on 4 Oct 2018]
Polarization and Chirality: the quantum features of the Quark Gluon Plasma
F. Becattini🇮🇹
Polarization and chirality are direct manifestations of quantum mechanics in the Quark Gluon Plasma as a relativistic fluid. This is one of the reasons why they are intriguing phenomena, that have attracted so much attention lately. In this talk I will review what is, in my view, the current theoretical understanding and highlight the most interesting recent result.
Comments:
7 pages, plenary talk given at the conference Quark Matter 2018. arXiv admin note: text overlap with arXiv:1711.08780
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1810.02706 [pdf]
NPA(2019)·3 citations
07
[Submitted on 5 Oct 2018]
Proton-proton 1S0 pairing in neutron star
Wenmei Guo🇨🇳 · J. M. Dong🇨🇳 · X. Shang🇨🇳 · H. F. Shang🇨🇳 · W. Zuo🇨🇳 · M. Colonna🇮🇹 · U. Lombardo🇮🇹
The onset of 1S0 proton spin-singlet pairing in neutron-star matter is studied in the framework of the BCS theory including medium polarization effects. The strong three-body coupling of the diproton pairs with the dense neutron environment and the self-energy effects severely reduce the gap magnitude, so to reshape the scenario of the proton superfluid phase inside the star. The vertex corrections due to the medium polarization are attractive in all isospin-asymmetry range at low density and tend to favor the pairing in that channel. However quantitative estimates of their effect on the energy gap do not give significant changes. Implications of the new scenario on the role of pairing in neutron-star cooling is briefly discussed.
Comments:
5 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1810.02709 [pdf]
NPA(2019)·12 citations
08
[Submitted on 24 Sept 2018] (cross-list from hep-ph)
P-wave heavy quarkonium spectrum with next-to-next-to-next-to-leading logarithmic accuracy
Clara Peset🇩🇪 · Antonio Pineda🇪🇸 · Jorge Segovia🇪🇸
We compute the heavy quarkonium mass of $l \neq = 0$ (angular momentum) states, with otherwise arbitrary quantum numbers, with next-next-to-next-to-leading logarithmic (N $^{3}$ LL) accuracy. This constitutes the first observable in heavy quarkonium for which two orders of the weak-coupling expansion sensitive to the ultrasoft scale are known and the resummation of ultrasoft logarithms is made. We also obtain, for the first time, resummed N $^{3}$ LL expressions for the different fine and hyperfine energy splittings of these states, which are not sensitive to the ultrasoft scale but still require resummation of (hard) logarithms. We do this analysis for the equal and non-equal mass cases. We also study an alternative computational scheme that treats the static potential exactly. We then perform a comprehensive phenomenological analysis: we apply these results to the $n = 2$ , $l = 1$ bottomonium, $B_{c}$ and charmonium systems and study their convergence.
Comments:
49 pages, 15 figures, 1 table
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1809.09124 [pdf]
PRD(2018)·26 citations
09
[Submitted on 29 Sept 2018] (cross-list from astro-ph.HE)
Axion cooling of neutron stars. II. Beyond hadronic axions
Armen Sedrakian (FIAS)🇩🇪
We study the axion cooling of neutron stars within the Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) model, which allows for tree level coupling of electrons to the axion {and locks the Peccei-Quinn charges of fermions via an angle parameter}. This extends our previous study [Phys. Rev. D 93, 065044 (2016)] limited to hadronic models of axions. We explore the two-dimensional space of axion parameters within the DFSZ model by comparing the theoretical cooling models with the surface temperatures of a few stars with measured surface temperatures. It is found that axions masses $m_{a} \geq 0.06$ to 0.12 eV can be excluded by x-ray observations of thermal emission of neutron stars (in particular by those of Cas A), the precise limiting value depending on the angle parameter of the DFSZ model. It is also found that axion emission by electron bremsstrahlung in neutron star crusts is negligible except for the special case where neutron Peccei-Quinn charge is small enough, so that the coupling of neutrons to axions can be neglected.
Comments:
v2: Extended discussion and results, matches published version, 10 pages, 9 figures; v1: 8 pages, 7 figures, uses RevTex
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1810.00190 [pdf]
PRD(2019)·81 citations
10
[Submitted on 4 Oct 2018] (cross-list from hep-ph)
Insight into Multiple Partonic Interactions and Production of Charmonia in p+p Collisions at the LHC energies
Raghunath Sahoo🇮🇳 · Dhananjaya Thakur🇮🇳 · Sudipan De🇮🇳 · Soumya Dansana🇮🇳
At the LHC energies, the underlying observables are of major topic of interest in high multiplicity $p + p$ collisions. Multiple Parton Interactions (MPI) is one of them, in which several interactions occur in a single $p + p$ collision. It is believed that MPI is the main reason behind the high multiplicity in $p + p$ collisions at the LHC. It was believed that MPI has only effect to the soft particle production, but recent ALICE result reveals that it can also affect the hard-particle production. In such case, the self normalized yield of heavy particle like $J/ ψ$ shows an increasing trend with event multiplicity. In the present contribution, we discuss the energy and multiplicity dependence of charmonium production to understand the effects of MPI on charmonium production.
Comments:
7 pages, To appear in the proceedings of 16th Conference on Flavor Physics and CP Violation - FPCP 2018 (Springer Proceedings in Physics). Presentation was given by Raghunath Sahoo
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1810.02386 [pdf]
Springer Proc.Phys.(2019)·1 citation
11
[Submitted on 5 Oct 2018] (cross-list from hep-ph)
Time reversal violating Magnetic Quadrupole Moment in heavy deformed nuclei
B. G. C. Lackenby🇦🇺 · V. V. Flambaum🇦🇺
The existence of permanent electric dipole moments (EDMs) and magnetic quadrupole moments (MQMs) violate both time reversal invariance ( $T$ ) and parity ( $P$ ). Following the $C P T$ theorem they also violate combined $C P$ symmetry. Nuclear EDM are completely screened in atoms and molecules while interaction between electrons and MQM creates atomic and molecular EDM which can be measured and used to test CP-violation theories. Nuclear MQM are produced by the nucleon-nucleon $T, P$ -odd interaction and by nucleon EDM. In this work we study the effect of enhancement of the nuclear MQM due to the nuclear deformation. Using the Nilsson model we calculate the nuclear MQMs for deformed nuclei of experimental interest and the resultant MQM energy shift in diatomic molecules of experimental interest $^{173}$ YbF , $^{177, 179}$ HfF $^{+}$ , $^{181}$ TaN, $^{181}$ TaO $^{+}$ , $^{229}$ ThO and $^{229}$ ThF $^{+}$ .
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
1810.02477 [pdf]
PRD(2018)·29 citations
12
[Submitted on 5 Oct 2018] (cross-list from hep-ph)
Electromagnetic proton-neutron mass difference
Oleksandr Tomalak🇩🇪
We discuss the Cottingham formula and evaluate the proton-neutron electromagnetic mass difference exploiting the state-of-the-art phenomenological input. We decompose individual contributions to the mass splitting into Born, inelastic and subtraction terms. We evaluate the subtraction-function contribution from the experimental input only and the Born term accounting for the modern low- $Q^{2}$ data.
Comments:
5 pages, 3 figures, journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1810.02502 [pdf]
Eur.Phys.J.Plus(2020)·10 citations
13
[Submitted on 5 Oct 2018] (cross-list from physics.atom-ph)
Resonant enhancement of oscillating electric field in atom
V.V. Flambaum🇦🇺 · I.B. Samsonov🇦🇺
When an atom is placed into an oscillating electric field with frequency far from atomic resonances, the atomic electrons partly shield this field at the nucleus. It is conjectured that when the frequency of electric field reaches an atomic resonance, the electric field at the nucleus may be significantly enhanced. In this paper, we systematically study the mechanisms of this enhancement and show that it may reach five orders in magnitude in particular cases. As an application, we consider laser-assisted neutron capture in 139-Lanthanum nucleus and screening and resonance enhancement of nuclear electromagnetic transitions by electrons.
Comments:
9 pages
Subjects:
Atomic Physics (physics.atom-ph); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1810.02601 [pdf]
PRA(2018)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE