Nuclear Theory·nucl-th

Wednesday·September 2, 2015

14 papers—9 primary·5 cross-listed

01
Coupled-channels description of multinucleon transfer and fusion reactions at energies near and far below the Coulomb barrier
Guillaume Scamps · Kouichi Hagino
We investigate heavy-ion multinucleon transfer reactions using the coupled-channels formalism. We first use the semi-classical approximation and show that a direct coupling between the entrance and the pair transfer channels improves a fit to the experimental one- and two-neutron transfer cross sections for the 40Ca+96Zr and 60Ni+116Sn systems. We then discuss the validity of the perturbative approach and highlight the effect of high order terms. The effect of absorption is also investigated for energies around the Coulomb barrier. Finally, we use a quantal coupled-channels approach to achieve a simultaneous description of the fusion cross sections and the transfer probabilities for the 40Ca+96Zr reaction. We find a significant effect of the couplings to the collective excited states on the transfer probabilities around the Coulomb barrier.
nucl-thnucl-exPRC(2015)·25 citations
02
Collective rotation from ab initio theory
M. A. Caprio · P. Maris · J. P. Vary · R. Smith
Through ab initio approaches in nuclear theory, we may now seek to quantitatively understand the wealth of nuclear collective phenomena starting from the underlying internucleon interactions. No-core configuration interaction (NCCI) calculations for p-shell nuclei give rise to rotational bands, as evidenced by rotational patterns for excitation energies, electromagnetic moments, and electromagnetic transitions. In this review, NCCI calculations of 7-9Be are used to illustrate and explore ab initio rotational structure, and the resulting predictions for rotational band properties are compared with experiment. We highlight the robustness of ab initio rotational predictions across different choices for the internucleon interaction.
nucl-thIJMPE(2015)·36 citations
03
Heavy Hadrons in Dense Matter
Laura Tolos🇪🇸 · Carmen Garcia-Recio🇪🇸 · Carlos Hidalgo-Duque🇪🇸 · Juan Nieves🇪🇸 · Olena Romanets🇳🇱 · Lorenzo Luis Salcedo🇪🇸 · Juan M. Torres-Rincon🇫🇷
We study the behavior of dynamically-generated baryon resonances with heavy-quark content within a unitarized coupled-channel theory in matter that fulfills heavy-quark spin symmetry constraints. We analyze the implications for the formation of charmed mesic nuclei and the propagation of heavy mesons in heavy-ion collisions from RHIC to FAIR.
nucl-thhep-exhep-phJ.Phys.Conf.Ser.(2016)·1 citation
04
Numerical accuracy of mean-field calculations in coordinate space
W. Ryssens · P.-H. Heenen · M. Bender
Background: Mean-field methods based on an energy density functional (EDF) are powerful tools used to describe many properties of nuclei in the entirety of the nuclear chart. The accuracy required on energies for nuclear physics and astrophysics applications is of the order of 500 keV and much effort is undertaken to build EDFs that meet this requirement. Purpose: The mean-field calculations have to be accurate enough in order to preserve the accuracy of the EDF. We study this numerical accuracy in detail for a specific numerical choice of representation for the mean-field equations that can accommodate any kind of symmetry breaking. Method: The method that we use is a particular implementation of 3-dimensional mesh calculations. Its numerical accuracy is governed by three main factors: the size of the box in which the nucleus is confined, the way numerical derivatives are calculated and the distance between the points on the mesh. Results: We have examined the dependence of the results on these three factors for spherical doubly-magic nuclei, neutron-rich $^{34}$ Ne, the fission barrier of $^{240}$ Pu and isotopic chains around Z = 50. Conclusions: Mesh calculations offer the user extensive control over the numerical accuracy of the solution scheme. By making appropriate choices for the numerical scheme the achievable accuracy is well below the model uncertainties of mean-field methods.
nucl-thPRC(2015)·42 citations
05
Electric dipole polarizability: from few- to many-body systems
Mirko Miorelli · Sonia Bacca · Nir Barnea · Gaute Hagen · Giuseppina Orlandini · Thomas Papenbrock
We review the Lorentz integral transform coupled-cluster method for the calculation of the electric dipole polarizability. We benchmark our results with exact hyperspherical harmonics calculations for 4He and then we move to a heavier nucleus studying 16O. We observe that the implemented chiral nucleon-nucleon interaction at next-to-next-to-next-to-leading order underestimates the electric dipole polarizability.
nucl-thnucl-exEPJ Web Conf.(2016)·3 citations
06
On growth of spinodal instabilities in nuclear matter-II:asymmetric matter
F. Acar · S. Ayik · O. Yilmaz · A. Gokalp
As an extension of our previous work, the growth of density fluctuations in the spinodal region of charge asymmetric nuclear matter is investigated in the basis of the stochastic mean-field approach in the non-relativistic framework. A complete treatment of density correlation functions are presented by including collective modes and non-collective modes as well.
nucl-thPRC(2015)·3 citations
07
The Quarkyonic Star
Kenji Fukushima🇯🇵 · Toru Kojo🇺🇸
We discuss theoretical scenarios on crossover between nuclear matter (NM) and quark matter (QM). We classify various possibilities into three major scenarios according to the onset of diquark degrees of freedom that characterizes color-superconducting (CSC) states. In the conventional scenario NM occurs at the liquid-gas (or liquid-vacuum at zero temperature) phase transition and QM occurs next, after which CSC eventually appears. With the effect of strong correlation, the BEC-BCS scenario implies that CSC occurs next to NM and QM comes last in the BCS regime. We adopt the quarkyonic scenario in which NM, QM, and CSC are theoretically indistinguishable and thus these names refer to not distinct states but relevant descriptions of the same physical system. Based on this idea we propose a natural scheme to interpolate NM near normal nuclear density and CSC with vector coupling at high baryon density. We finally discuss the mass-radius relation of the neutron star and constraints on parameters in the proposed scheme.
nucl-thastro-ph.HEhep-phApJ(2016)·102 citations
08
Parking-garage structures in astrophysics and biophysics
C. J. Horowitz · D. K. Berry · M. E. Caplan · Greg Huber · A. S. Schneider
A striking shape was recently observed for the cellular organelle endoplasmic reticulum consisting of stacked sheets connected by helical ramps. This shape is interesting both for its biological function, to synthesize proteins using an increased surface area for ribosome factories, and its geometric properties that may be insensitive to details of the microscopic interactions. In the present work, we find very similar shapes in our molecular dynamics simulations of the nuclear pasta phases of dense nuclear matter that are expected deep in the crust of neutron stars. There are dramatic differences between nuclear pasta and terrestrial cell biology. Nuclear pasta is 14 orders of magnitude denser than the aqueous environs of the cell nucleus and involves strong interactions between protons and neutrons, while cellular scale biology is dominated by the entropy of water and complex assemblies of biomolecules. Nonetheless the very similar geometry suggests both systems may have similar coarse-grained dynamics and that the shapes are indeed determined by geometrical considerations, independent of microscopic details. Many of our simulations self-assemble into flat sheets connected by helical ramps. These ramps may impact the thermal and electrical conductivities, viscosity, shear modulus, and breaking strain of neutron star crust. The interaction we use, with Coulomb frustration, may provide a simple model system that reproduces many biologically important shapes.
nucl-thastro-ph.HEcond-mat.softphysics.bio-phPRC(2016)·59 citations
09
Ab initio calculation of the electromagnetic and neutral-weak response functions of 4He and 12C
A. Lovato🇺🇸 · O. Benhar🇮🇹 · J. Carlson🇺🇸 · S. Gandolfi🇺🇸 · Steven C. Pieper🇺🇸 · N. Rocco🇮🇹 · R. Schiavilla🇺🇸
Precise measurement of neutrino oscillations, and hence the determination of their masses demands a quantitative understanding of neutrino-nucleus interactions. To this aim, two-body meson-exchange currents have to be accounted for along within realistic models of nuclear dynamics. We summarize our progresses towards the construction of a consistent framework, based on quantum Monte Carlo methods and on the spectral function approach, that can be exploited to accurately describe neutrino interactions with atomic nuclei over the broad kinematical region covered by neutrino experiments.
nucl-thhep-exEPJ Web Conf.(2016)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE