Nuclear Theory·nucl-th

Wednesday·June 22, 2016

12 papers—5 primary·7 cross-listed

01
[Submitted on 13 Jun 2016]
Landscape of atomic nuclear shapes
Chang-Bum Moon
We exhibit a wide variety of the nuclear shape phases over the nuclear chart along with a shell model scheme. Various nuclear shapes are demonstrated within the framework of proton-neutron spin-orbital interactions; ferro-deformed, sub-ferro-deformed, and spherical shapes. The spherical shape is classified into the three magic-number categories in view of a large shell gap mechanism; double-magic nuclei I, double magic nuclei II, and double magic nuclei III. We discuss nuclear shape coexistence in the space Z = 76 to 84 as providing a new way to understanding the dynamical shape phases.
Comments:
8 pages, 5 figures, Keywords: double-magic nuclei I, double-magic nuclei II, double-magic nuclei III, ferro-deformation, sub-ferro-deformation, reinforced double-shell closures, sub-reinforced double-shell closures, pseudo-(sub)shell, shape phase transitions, shape coexistence
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1606.06302 [pdf]
0 citations
02
[Submitted on 20 Jun 2016]
Local chiral potentials and the structure of light nuclei
Maria Piarulli🇺🇸 · Luca Girlanda🇮🇹 · Rocco Schiavilla🇺🇸 · Alejandro Kievsky🇮🇹 · Alessandro Lovato🇺🇸 · Laura E. Marcucci🇮🇹 · Steven C. Pieper🇺🇸 · Michele Viviani🇮🇹 · Robert B. Wiringa🇺🇸
We present fully local versions of the minimally non-local nucleon-nucleon potentials constructed in a previous paper [M.\ Piarulli {\it et al.}, Phys.\ Rev.\ C {\bf 91}, 024003 (2015)], and use them in hypersperical-harmonics and quantum Monte Carlo calculations of ground and excited states of $^{3}$ H, $^{3}$ He, $^{4}$ He, $^{6}$ He, and $^{6}$ Li nuclei. The long-range part of these local potentials includes one- and two-pion exchange contributions without and with $Δ$ -isobars in the intermediate states up to order $Q^{3}$ ( $Q$ denotes generically the low momentum scale) in the chiral expansion, while the short-range part consists of contact interactions up to order $Q^{4}$ . The low-energy constants multiplying these contact interactions are fitted to the 2013 Granada database in two different ranges of laboratory energies, either 0--125 MeV or 0--200 MeV, and to the deuteron binding energy and $nn$ singlet scattering length. Fits to these data are performed for three models characterized by long- and short-range cutoffs, $R_{L}$ and $R_{S}$ respectively, ranging from $(R_{L}, R_{S}) = (1.2, 0.8)$ fm down to $(0.8, 0.6)$ fm. The long-range (short-range) cutoff regularizes the one- and two-pion exchange (contact) part of the potential.
Comments:
29 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1606.06335 [pdf]
PRC(2016)·183 citations
03
[Submitted on 21 Jun 2016]
Emission of neutron-proton and proton-proton pairs in electron scattering induced by meson-exchange currents
I. Ruiz Simo🇪🇸 · J.E. Amaro🇪🇸 · M.B. Barbaro🇮🇹 · A. De Pace🇮🇹 · J.A. Caballero🇪🇸 · G.D. Megias🇪🇸 · T.W. Donnelly🇺🇸
We use a relativistic model of meson-exchange currents to compute the proton-neutron and proton-proton yields in $(e, e^{'})$ scattering from $^{12}$ C in the 2p-2h channel. We compute the response functions and cross section with the relativistic Fermi gas model for a range of kinematics from intermediate to high momentum transfers. We find a large contribution of neutron-proton configurations in the initial state, as compared to proton-proton pairs. The different emission probabilities of distinct species of nucleon pairs are produced in our model only by meson-exchange currents, mainly by the $Δ$ isobar current. We also analyze the effect of the exchange contribution and show that the direct/exchange interference strongly affects the determination of the np/pp ratio.
Comments:
5 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1606.06480 [pdf]
PRC(2016)·15 citations
04
[Submitted on 21 Jun 2016]
Mass dependence and isospin dependence of short-range correlated pairs
U. Mosel🇩🇪 · K. Gallmeister🇩🇪
The target-mass number dependence of nucleon-nucleon pairs with short-range correlations is explored in a physically transparent geometrical model within a zero-range approximation. The observed $A$ dependence of 2-nucleon ejection cross sections in $(e, e^{'})$ reactions is found to reflect the mass dependence of nuclear density distributions. A parametrization of this $A$ dependence is given. The $A$ dependence of proton-proton vs.\ proton-neutron pairs relative to $^{12}$ C is also analyzed in this model. It can be understood using simple combinatorics without any additional isospin dependence.
Comments:
Version as accepted for publication in Physical Review C
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1606.06499 [pdf]
PRC(2016)·12 citations
05
[Submitted on 21 Jun 2016]
Particle production and equilibrium properties within a new hadron transport approach for heavy-ion collisions
J. Weil🇩🇪 · V. Steinberg🇩🇪 · J. Staudenmaier🇩🇪 · L.G. Pang🇩🇪 · D. Oliinychenko🇩🇪 · J. Mohs🇩🇪 · M. Kretz🇩🇪 · T. Kehrenberg🇩🇪 · A. Goldschmidt🇩🇪 · B. Bäuchle🇩🇪 · J. Auvinen🇩🇪 · M. Attems🇩🇪 · H. Petersen🇩🇪
The microscopic description of heavy-ion reactions at low beam energies is achieved within hadronic transport approaches. In this article a new approach SMASH (Simulating Many Accelerated Strongly-interacting Hadrons) is introduced and applied to study the production of non-strange particles in heavy-ion reactions at $E_{kin} = 0.4 - 2 A$ GeV. First, the model is described including details about the collision criterion, the initial conditions and the resonance formation and decays. To validate the approach, equilibrium properties such as detailed balance are presented and the results are compared to experimental data for elementary cross sections. Finally results for pion and proton production in C+C and Au+Au collisions is confronted with HADES and FOPI data. Predictions for particle production in $π + A$ collisions are made.
Comments:
30 pages, 30 figures, replaced with published version; only minor changes
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1606.06642 [pdf]
PRC(2016)·454 citations

Affiliations

first authorsco-authorsvia INSPIRE

Landscape of atomic nuclear shapes

Local chiral potentials and the structure of light nuclei

Emission of neutron-proton and proton-proton pairs in electron scattering induced by meson-exchange currents

Mass dependence and isospin dependence of short-range correlated pairs

Particle production and equilibrium properties within a new hadron transport approach for heavy-ion collisions

Affiliations