Nuclear Theory·nucl-th

Tuesday·January 26, 2016

13 papers—6 primary·7 cross-listed

01
[Submitted on 23 Jan 2016]
Nuclear charge and neutron radii and nuclear matter: trend analysis
P.-G. Reinhard · W. Nazarewicz
Radii of charge and neutron distributions are fundamental nuclear properties. They depend on both nuclear interaction parameters related to the equation of state of infinite nuclear matter and on quantal shell effects, which are strongly impacted by the presence of nuclear surface. In this work, by studying the dependence of charge and neutron radii, and neutron skin, on nuclear matter parameters, we assess different mechanisms that drive nuclear sizes. We apply nuclear density functional theory using a family of Skyrme functionals obtained by means of different optimization protocols targeting specific nuclear properties. By performing the Monte-Carlo sampling of reasonable functionals around the optimal parametrization, we study correlations between nuclear matter paramaters and observables characterizing charge and neutron distributions. We demonstrate the existence of the strong converse relation between the nuclear charge radii and the saturation density of symmetric nuclear matter and also between the neutron skins and the slope of the symmetry energy. For functionals optimized to experimental binding energies only, proton and neutron radii are weakly correlated due to canceling trends from different nuclear matter parameters. We show that by requiring that the nuclear functional reproduces the empirical saturation point of symmetric nuclear matter practically fixes the charge (or proton) radii, and vice versa. The neutron skin uncertainty primarily depends on the slope of the symmetry energy. Consequently, imposing a constraint on both $ρ_{0}$ and $L$ practically determines the nuclear size, modulo small variations due to shell effects.
Comments:
5 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1601.06324 [pdf]
PRC(2016)·57 citations
02
[Submitted on 24 Jan 2016]
Exotic neutron-rich medium-mass nuclei with realistic nuclear forces
Naofumi Tsunoda · Takaharu Otsuka · Noritaka Shimizu · Morten Hjorth-Jensen · Kazuo Takayanagi · Toshio Suzuki
We present the first application of the newly developed EKK theory of the effective nucleon-nucleon interaction to shell-model studies of exotic nuclei, including those where conventional approaches with fitted interactions encounter difficulties. This EKK theory enables us to derive the interaction suitable for several major shells ( $s d$ + $p f$ in this work). By using such an effective interaction obtained from the Entem-Machleidt QCD-based $χ N^{3} LO$ interaction and the Fujita-Miyazawa three-body force, the energies, E2 properties and spectroscopic factors of low-lying states of neutron-rich Ne, Mg and Si isotopes are nicely described, as the first shell-model description of the "island of inversion" without fit of the interaction. The long-standing question as to how particle-hole excitations occur across the $s d$ - $p f$ magic gap is clarified with distinct differences from the conventional approaches. The shell evolution is shown to appear similarly to earlier studies.
Comments:
5pages, 4figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1601.06442 [pdf]
PRC(2017)·91 citations
03
[Submitted on 25 Jan 2016]
Dynamical Coupling of Pygmy and Giant Resonances in Relativistic Coulomb Excitation
N.S. Brady · T. Aumann · C.A. Bertulani · J.O. Thomas
We study the Coulomb excitation of pygmy dipole resonances (PDR) in heavy ion reactions at 100 MeV/nucleon and above. The reactions 68Ni+197Au and 68Ni+208Pb are taken as a practical examples. Our goal is to address the question of the influence of giant resonances on the PDR as the dynamics of the collision evolves. We show that the coupling to the giant resonances affects considerably the excitation probabilities of the PDR, a result that indicates the need of an improved theoretical treatment of the reaction dynamics at these bombarding energies.
Comments:
6 pages, 4 figures, accepted for publication in Physics Letters B
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1601.06469 [pdf]
PLB(2016)·5 citations
04
[Submitted on 25 Jan 2016]
On Exotic Systems of Baryons in Chiral Soliton Models
Vladimir Kopeliovich (INR, Moscow & NORDITA)🇷🇺
The role of zero mode quantum corrections to the energy of baryonic systems with exotic quantum numbers (strangeness) is discussed. A simple expression for the contribution depending on strange inertia is obtained in the $S U (3) -$ collective coordinate quantization approach, and it is shown that this correction stabilizes the systems the stronger the greater their baryon number is. Furthemore, systems are considered which could be interpreted in the quark model language as containing additional $q q ˉ -$ pairs. It is argued that a strange skyrmion crystal should have additional binding in comparison with the $S U (2) -$ quantized neutron crystal.
Comments:
6 pages, no figures; electronic version of the paper published in Phys. Lett. B259 (1991) 234; NORDITA preprint 90/55 (1990); sections names and 2 footnotes added
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
1601.06493 [pdf]
PLB(1991)·36 citations
05
[Submitted on 25 Jan 2016]
Time-dependent Hartree-Fock calculations for multinucleon transfer and quasifission processes in the $^{64}$ Ni+ $^{238}$ U reaction
Kazuyuki Sekizawa · Kazuhiro Yabana
Background: Multinucleon transfer (MNT) and quasifission (QF) processes are dominant processes in low-energy collisions of two heavy nuclei. They are expected to be useful to produce neutron-rich unstable nuclei. Nuclear dynamics leading to these processes depends sensitively on nuclear properties such as deformation and shell structure. Purpose: We elucidate reaction mechanisms of MNT and QF processes involving heavy deformed nuclei, making detailed comparisons between microscopic time-dependent Hartree-Fock (TDHF) calculations and measurements for the $^{64}$ Ni+ $^{238}$ U reaction. Methods: Three-dimensional Skyrme-TDHF calculations are performed. Particle-number projection method is used to evaluate MNT cross sections from the TDHF wave function after collision. Results: Fragment masses, total kinetic energy (TKE), scattering angle, contact time, and MNT cross sections are investigated for the $^{64}$ Ni+ $^{238}$ U reaction. They show reasonable agreements with measurements. At small impact parameters, collision dynamics depends sensitively on the orientation of deformed $^{238}$ U. In tip (side) collisions, we find a larger (smaller) TKE and a shorter (longer) contact time. In tip collisions, we find a strong influence of quantum shells around $^{208}$ Pb. Conclusions: It is confirmed that the TDHF calculations reasonably describe both MNT and QF processes in the $^{64}$ Ni+ $^{238}$ U reaction. Analyses of this system indicates the significance of the nuclear structure effects such as deformation and quantum shells in nuclear reaction dynamics at low energies.
Comments:
14 pages, 10 figures; v2 - Additional calculations were performed and results shown in Sec.III B have been revised. Version accepted for publication in PRC, selected as Editors' Suggestion. See also Supplemental Material at http://link.aps.org/supplemental/10.1103/PhysRevC.93.054616 for movies of the reactions
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1601.06656 [pdf]
PRC(2016)·146 citations
06
[Submitted on 25 Jan 2016]
Gamow shell model description of radiative capture reactions $^{6}$ Li $(p, γ)$ $^{7}$ Be and $^{6}$ Li $(n, γ)$ $^{7}$ Li
G.X. Dong🇫🇷 · N. Michel🇫🇷 · K. Fossez🇺🇸 · M. Płoszajczak🇫🇷 · Y. Jaganathen🇺🇸 · R.M. Id Betan🇦🇷
According to standard stellar evolution, lithium abundance is believed to be a useful indicator of the stellar age. However, many evolved stars like red giants show huge fluctuations around expected theoretical abundances that are not yet fully understood. The better knowledge of nuclear reactions that contribute to the creation and destruction of lithium can help to solve this puzzle. In this work we apply the Gamow shell model (GSM) formulated in the coupled-channel representation (GSM-CC) to investigate the mirror radiative capture reactions $^{6}$ Li $(p, γ)$ $^{7}$ Be and $^{6}$ Li $(n, γ)$ $^{7}$ Li. The cross-sections are calculated using a translationally invariant Hamiltonian with the finite-range interaction which is adjusted to reproduce spectra, binding energies and one-nucleon separation energies in $^{6 - 7}$ Li, $^{7}$ Be. All relevant $E 1$ , $M 1$ , and $E 2$ transitions from the initial continuum states to the final bound states $J = 3/2_{1}^{-}$ and $J = 1/2^{-}$ of $^{7}$ Li and $^{7}$ Be are included. We demonstrate that the $s$ -wave radiative capture of proton (neutron) to the first excited state $J^{π} = 1/ 2_{1}^{+}$ of $^{7}$ Be ( $^{7}$ Li) is crucial and increases the total astrophysical $S$ -factor by about 40 \%.
Comments:
arXiv admin note: text overlap with arXiv:1502.01631
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1601.06660 [pdf]
J.Phys.G(2017)·37 citations
07
[Submitted on 25 Jan 2016] (cross-list from hep-ph)
Charmed baryons and their interactions
Atsushi Hosaka🇯🇵 · Emiko Hiyama🇯🇵 · SangHo Kim🇯🇵 · Hyun-Chul Kim🇯🇵 · Hideko Nagahiro🇯🇵 · Hiroyuki Noumi🇯🇵 · Makoto Oka🇯🇵 · Kotaro Shirotori🇯🇵 · Tetsuya Yoshida🇯🇵 · Shigehiro Yasui🇯🇵
In this proceedings report, we discuss unique features of charmed, or in general heavy, baryons with one heavy quark. A well and long-term known phenomena, the distinction of the two modes of the rho and lambda type of a three-quark system is revisited. The difference of these modes may be tested in the production and decay reactions of the baryons which may be tested in the future experiments at J-PARC.
Comments:
10 pages, proceedings for HYP2015, Sendai, Sept. 7-12, 2015
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1601.06457 [pdf]
JPS Conf.Proc.(2017)·0 citations
08
[Submitted on 25 Jan 2016] (cross-list from hep-ph)
Progress on nuclear modifications of structure functions
S. Kumano (KEK/J-PARC)🇯🇵
We report progress on nuclear structure functions, especially on their nuclear modifications and a new tensor structure function for the deuteron. To understand nuclear structure functions is an important step toward describing nuclei and QCD matters from low to high densities and from low to high energies in terms of fundamental quark and gluon degrees of freedom beyond conventional hadron and nuclear physics. It is also practically important for understanding new phenomena in high-energy heavy-ion collisions at RHIC and LHC. Furthermore, since systematic errors of current neutrino-oscillation experiments are dominated by uncertainties of neutrino-nucleus interactions, such studies are valuable for finding new physics beyond current framework. Next, a new tensor-polarized structure function $b_{1}$ is discussed for the deuteron. There was a measurement by HERMES; however, its data are inconsistent with the conventional convolution estimate based on the standard deuteron model with D-state admixture. This fact suggests that a new hadronic phenomenon should exist in the tensor-polarized deuteron at high energies, and it will be experimentally investigated at JLab from the end of 2010's.
Comments:
6 pages, LaTeX, 2 style files, 4 eps files, to be published in EPJ-web of Conferences, Sixth International Conference on Physics Opportunities at an Electron-Ion Collider (POETIC6), Ecole Polytechnique, Palaiseau, France, September 7-11, 2015
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1601.06499 [pdf]
EPJ Web Conf.(2016)·0 citations
09
[Submitted on 25 Jan 2016] (cross-list from hep-ph)
The Subtleties of the Wigner Function Formulation of the Chiral Magnetic Effect
Yan Wu🇨🇳 · Defu Hou🇨🇳 · Hai-cang Ren🇨🇳
We assess the applicability of the Wigner function formulation in its present form to the chiral Magnetic Effect and noted some issues regarding the conservation and the consistency of the electric current in the presence of an inhomogeneous and time dependent axial chemical potential. The problems are rooted in the ultraviolet divergence of the underlying field theory associated with the axial anomaly and can be fixed with the Pauli-Villars regularization of the Wigner function.
Comments:
8 pages in Revtex, a new section is added about CME with PV-regularized Wigner function
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1601.06520 [pdf]
PRD(2017)·24 citations
10
[Submitted on 25 Jan 2016] (cross-list from hep-ph)
Energy loss at NLO in a high-temperature Quark-Gluon Plasma
Jacopo Ghiglieri🇨🇭
We present an extension of the Arnold-Moore-Yaffe kinetic equations for jet energy loss to NLO in the strong coupling constant. A novel aspect of the NLO analysis is a consistent description of wider-angle bremsstrahlung (semi-collinear emissions), which smoothly interpolates between 2<->2 scattering and collinear bremsstrahlung. We describe how many of the ingredients of the NLO transport equations (such as the drag coefficient) can be expressed in terms of Wilson line operators and can be computed using a Euclidean formalism or sum rules, both motivated by the analytic properties of amplitudes at light-like separations. We conclude with an outlook on the computation of the shear viscosity at NLO.
Comments:
4 pages, 4 figures. To appear in the proceedings of Quark Matter 2015 (Kobe, Japan)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1601.06545 [pdf]
NPA(2016)·0 citations
11
[Submitted on 25 Jan 2016] (cross-list from hep-ph)
Centrality-dependent forward $J / ψ$ production in high energy proton-nucleus collisions
B. Ducloué🇫🇮 · T. Lappi🇫🇮 · H. Mäntysaari🇺🇸
Forward $J / ψ$ production and suppression in high energy proton-nucleus collisions can be an important probe of gluon saturation. In an earlier work we studied this process in the Color Glass Condensate framework and showed that using the Glauber approach to extrapolate the dipole cross section of a proton to a nucleus leads to results closer to experimental data than previous calculations in this framework. Here we investigate the centrality dependence of the nuclear suppression in this model and show a comparison of our results with recent LHC data.
Comments:
6 pages, 2 figures. Contribution to the proceedings of the 6th International Conference on Physics Opportunities at an Electron-Ion Collider (POETIC6), September 7-11, 2015, Palaiseau, France
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1601.06557 [pdf]
EPJ Web Conf.(2016)·2 citations
12
[Submitted on 25 Jan 2016] (cross-list from hep-ph)
Next-to-leading order Balitsky-Kovchegov equation with resummation
T. Lappi🇫🇮 · H. Mäntysaari🇺🇸
We solve the Balitsky-Kovchegov evolution equation at next-to-leading order accuracy including a resummation of large single and double transverse momentum logarithms to all orders. We numerically determine an optimal value for the constant under the large transverse momentum logarithm that enables including a maximal amount of the full NLO result in the resummation. When this value is used the contribution from the $α_{s}^{2}$ terms without large logarithms is found to be small at large saturation scales and at small dipoles. Close to initial conditions relevant for phenomenological applications these fixed order corrections are shown to be numerically important.
Comments:
10 pages, 8 figures. RevTex. v2: small clarifications to text, published in Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1601.06598 [pdf]
PRD(2016)·129 citations
13
[Submitted on 25 Jan 2016] (cross-list from hep-ph)
Electron-deuteron DIS with spectator tagging at EIC: Development of theoretical framework
W. Cosyn🇧🇪 · V. Guzey🇷🇺 · M. Sargsian🇺🇸 · M. Strikman🇺🇸 · C. Weiss🇺🇸
An Electron-Ion Collider (EIC) would enable next-generation measurements of deep-inelastic scattering (DIS) on the deuteron with detection of a forward-moving nucleon (p, n) and measurement of its recoil momentum ("spectator tagging"). Such experiments offer full control of the nuclear configuration during the high-energy process and can be used for precision studies of the neutron's partonic structure and its spin dependence, nuclear modifications of partonic structure, and nuclear shadowing at small x. We review the theoretical description of spectator tagging at EIC energies (light-front nuclear structure, on-shell extrapolation in the recoil nucleon momentum, final-state interactions, diffractive effects at small x) and report about on-going developments.
Comments:
7 pages, 3 figures. Proceedings of 6th International Conference on Physics Opportunities at an Electron-Ion Collider (POETIC6), Palaiseau, France, 7-11 September 2015
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1601.06665 [pdf]
EPJ Web Conf.(2016)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE