Nuclear Theory·nucl-th

Tuesday·March 28, 2017

16 papers—8 primary·8 cross-listed

01
[Submitted on 25 Mar 2017]
Effects of Neutron-Proton Short-Range Correlation on the Equation of State of Dense Neutron-Rich Nucleonic Matter
Bao-Jun Cai🇺🇸 · Bao-An Li🇺🇸 · Lie-Wen Chen🇨🇳
The strongly isospin-dependent tensor force leads to short-range correlations (SRC) between neutron-proton (deuteron-like) pairs much stronger than those between proton-proton and neutron-neutron pairs. As a result of the short-range correlations, the single-nucleon momentum distribution develops a high-momentum tail above the Fermi surface. Because of the strongly isospin-dependent short-range correlations, in neutron-rich matter a higher fraction of protons will be depleted from its Fermi sea and populate above the Fermi surface compared to neutrons. This isospin-dependent nucleon momentum distribution may have effects on: (1) nucleon spectroscopic factors of rare isotopes, (2) the equation of state especially the density dependence of nuclear symmetry energy, (3) the coexistence of a proton-skin in momentum space and a neutron-skin in coordinate space (i.e., protons move much faster than neutrons near the surface of heavy nuclei). In this talk, we discuss these features and their possible experimental manifestations. As an example, SRC effects on the nuclear symmetry energy are discussed in detail using a modified Gogny-Hartree-Fock (GHF) energy density functional (EDF) encapsulating the SRC-induced high momentum tail (HMT) in the single-nucleon momentum distribution.
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
arXiv:
1703.08743 [pdf]
AIP Conf.Proc.(2018)·6 citations
02
[Submitted on 26 Mar 2017]
Interesting effect of the nd -> p(nn) reaction
R. A. Shindin🇷🇺 · D. K. Guriev🇷🇺 · A. N. Livanov🇷🇺 · I. P. Yudin🇷🇺
The reaction nd -> p(nn) produce two slow neutrons in the final state instead of deuteron. In the first view we can take into account the binding energy e ~ 2.23 MeV but this approach can not explain all features which are observed in the momentum spectrum of the secondaries protons. We need to suppose that two slow neutrons in the final state form the intermediate system which has own distribution of internal Fermi momentum.
Comments:
in Russian
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1703.08820 [pdf]
1 citation
03
[Submitted on 26 Mar 2017]
Estimating parameter uncertainty in binding-energy models by the frequency-domain bootstrap
G.F. Bertsch · Derek Bingham
We propose using the frequency-domain bootstrap (FDB) to estimate errors of modeling parameters when the modeling error is itself a major source of uncertainty. Unlike the usual bootstrap or the simple $χ^{2}$ analysis, the FDB can take into account correlations between errors. It is also very fast compared to the the Gaussian process Bayesian estimate as often implemented for computer model calibration. The method is illustrated drop model of nuclear binding energies. We find that the FDB gives a more conservative estimate of the uncertainty in liquid drop parameters in better accord with more empirical estimates. For the nuclear physics application, there no apparent obstacle to apply the method to the more accurate and detailed models based on density-functional theory.
Comments:
10 pages, 5 figures, submitted to Physical Review Letters
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1703.08844 [pdf]
PRL(2017)·28 citations
04
[Submitted on 27 Mar 2017]
Nuclear physics insights for new-physics searches using nuclei: Neutrinoless $β β$ decay and dark matter direct detection
Javier Menéndez🇯🇵
Experiments using nuclei to probe new physics beyond the Standard Model, such as neutrinoless $β β$ decay searches testing whether neutrinos are their own antiparticle, and direct detection experiments aiming to identify the nature of dark matter, require accurate nuclear physics input for optimizing their discovery potential and for a correct interpretation of their results. This demands a detailed knowledge of the nuclear structure relevant for these processes. For instance, neutrinoless $β β$ decay nuclear matrix elements are very sensitive to the nuclear correlations in the initial and final nuclei, and the spin-dependent nuclear structure factors of dark matter scattering depend on the subtle distribution of the nuclear spin among all nucleons. In addition, nucleons are composite and strongly interacting, which implies that many-nucleon processes are necessary for a correct description of nuclei and their interactions. It is thus crucial that theoretical studies and experimental analyses consider $β$ decays and dark matter interactions with a coupling to two nucleons, called two-nucleon currents.
Comments:
11 pages, 5 figures, invited parallel talk at the XIIth Quark Confinement & the Hadron Spectrum conference, Thessaloniki, Greece, 2016
Subjects:
Nuclear Theory (nucl-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1703.08921 [pdf]
EPJ Web Conf.(2017)·4 citations
05
[Submitted on 27 Mar 2017]
Rotating hybrid stars with the Dyson-Schwinger quark model
J.-B. Wei🇨🇳 · H. Chen🇨🇳 · G. F. Burgio🇮🇹 · H.-J. Schulze🇮🇹
We study rapidly rotating hybrid stars with the Dyson-Schwinger model for quark matter and the Brueckner-Hartree-Fock many-body theory with realistic two-body and three-body forces for nuclear matter. We determine the maximum gravitational mass, equatorial radius, and rotation frequency of stable stellar configurations by considering the constraints of the Keplerian limit and the secular axisymmetric instability, and compare with observational data. We also discuss the rotational evolution for constant baryonic mass, and find a spinup phenomenon for supramassive stars before they collapse to black holes.
Comments:
9 pages,9 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1703.08952 [pdf]
PRD(2017)·19 citations
06
[Submitted on 27 Mar 2017]
Structure of Exotic Nuclei: A Theoretical Review
Shan-Gui Zhou
The study of exotic nuclei---nuclei with the ratio of neutron number $N$ to proton number $Z$ deviating much from that of those found in nature---is at the forefront of nuclear physics research because it can not only reveal novel nuclear properties and thus enrich our knowledge of atomic nuclei, but also help us to understand the origin of chemical elements in the nucleosynthesis. With the development of radioactive ion beam facilities around the world, more and more unstable nuclei become experimentally accessible. Many exotic nuclear phenomena have been observed or predicted in nuclei far from the $β$ -stability line, such as neutron or proton halos, the shell evolution and changes of nuclear magic numbers, the island of inversion, soft-dipole excitations, clustering effects, new radioactivities, giant neutron halos, the shape decoupling between core and valence nucleons in deformed halo nuclei, etc. In this contribution, I will present a review of theoretical study of exotic nuclear structure. I will first introduce characteristic features and new physics connected with exotic nuclear phenomena: the weakly-bound feature, the large-spatial extension in halo nuclei, deformation effects in halo nuclei, the shell evolution, new radioactivities and clustering effects. Then I will highlight some recent progresses corresponding to these features.
Comments:
11 pages, 2 figures; plenary talk given at the 26th International Nuclear Physics Conference (INPC2016), Sep. 11-16, 2016, Adelaide, Australia
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1703.09045 [pdf]
PoS(2017)·16 citations
07
[Submitted on 24 Mar 2017]
The $_{ΛΛ}^{4} n$ system
H. Garcilazo🇲🇽 · A. Valcarce🇪🇸 · J. Vijande🇪🇸
Using local central Yukawa-type Malfliet-Tjon interactions reproducing the low-energy parameters and phase shifs of the $nn$ system and the latest updates of the $n Λ$ and $ΛΛ$ Nijmegen ESC08c potentials we study the possible existence of a $_{ΛΛ}^{4} n$ bound state. Our results indicate that the $_{ΛΛ}^{4} n$ is unbound, being just above threshold. We discuss the role played by the $^{1} S_{0}$ $nn$ repulsive term of the Yukawa-type Malfliet-Tjon interaction.
Comments:
13 pages, 4 figures. To be published in Chinese Physics C
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1703.09067 [pdf]
CPC(2017)·9 citations
08
[Submitted on 27 Mar 2017]
Traces of non-equilibrium dynamics in relativistic heavy-ion collisions
Yingru Xu🇺🇸 · Pierre Moreau🇩🇪 · Taesoo Song🇩🇪 · Marlene Nahrgang🇺🇸 · Steffen A. Bass🇺🇸 · Elena Bratkovskaya🇩🇪
The impact of non-equilibrium effects on the dynamics of heavy-ion collisions is investigated by comparing a non-equilibrium transport approach, the Parton-Hadron-String-Dynamics (PHSD), to a 2D+1 viscous hydrodynamical model, which is based on the assumption of local equilibrium and conservation laws. Starting the hydrodynamical model from the same non-equilibrium initial condition as in the PHSD, using an equivalent lQCD Equation-of-State (EoS), the same transport coefficients, i.e. shear viscosity $η$ and the bulk viscosity $ζ$ in the hydrodynamical model, we compare the time evolution of the system in terms of energy density, Fourier transformed energy density, spatial and momentum eccentricities and ellipticity in order to quantify the traces of non-equilibrium phenomena. In addition, we also investigate the role of initial pre-equilibrium flow on the hydrodynamical evolution and demonstrate its importance for final state observables. We find that due to non-equilibrium effects, the event-by-event transport calculations show large fluctuations in the collective properties, while ensemble averaged observables are close to the hydrodynamical results.
Comments:
19 pages, 16 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1703.09178 [pdf]
PRC(2017)·25 citations

Affiliations

first authorsco-authorsvia INSPIRE