Nuclear Theory·nucl-th

Tuesday·April 25, 2017

14 papers—8 primary·6 cross-listed

01
The neutron skin thickness of $^{48}$ Ca from a nonlocal-dispersive-optical-model analysis
M.H. Mahzoon · M.C. Atkinson · R.J. Charity · W.H. Dickhoff
A nonlocal dispersive-optical-model analysis has been carried out for neutrons and protons in $^{48}$ Ca. Elastic-scattering angular distributions, total and reaction cross sections, single-particle energies, the neutron and proton numbers, and the charge distribution have been fitted to extract the neutron and proton self-energies both above and below the Fermi energy. From the single-particle propagator resulting from these self-energies we have determined the charge and neutron matter distributions in $^{48}$ Ca. A neutron skin of 0.249 $\pm$ 0.023~fm is deduced. The energy dependence of the total neutron cross sections is shown to have strong sensitivity to the skin thickness.
nucl-thPRL(2017)·52 citations
02
Charge redistribution from novel magneto-vorticity coupling in anomalous hydrodynamics
Koichi Hattori🇨🇳 · Yi Yin🇺🇸
We discuss new transport phenomena in the presence of both a strong magnetic field and a vortex field. Their interplay induces a charge distribution and a current along the magnetic field. We show that the associated transport coefficients can be obtained from a simple analysis of the single-particle distribution functions and also from the Kubo formula calculation. The consistent results from these analyses suggest that the transport coefficients are tied to the chiral anomaly in the (1+1) dimension because of the dimensional reduction in the lowest Landau levels.
nucl-thhep-phnucl-exNPA(2017)·0 citations
03
Equation of State of Quantum Gases Beyond the Van der Waals Approximation
K. A. Bugaev · A. I. Ivanytskyi · V. V. Sagun · E. G. Nikonov · G. M. Zinovjev
A recently suggested equation of state with the induced surface tension is generalized to the case of quantum gases with mean-field interaction. The self-consistency conditions of such a model and the necessary one to obey the Third Law of thermodynamics are found. The quantum virial expansion of the Van der Waals models of such a type is analyzed and its virial coefficients are given. In contrast to traditional beliefs, it is shown that an inclusion of the third and higher virial coefficients of the gas of hard spheres into the interaction pressure of the Van der Waals models either breaks down the Third Law of thermodynamics or does not allow one to go beyond the Van der Waals approximation at low temperatures. It is demonstrated that the generalized equation of state with the induced surface tension allows one to avoid such problems and to safely go beyond the Van der Waals approximation. Besides, the effective virial expansion for quantum version of the induced surface tension equation of state is established and all corresponding virial coefficients are found exactly.The explicit expressions for the true quantum virial coefficients of an arbitrary order of this equation of state are given in the low density approximation. A few basic constraints on such models which are necessary to describe the nuclear and hadronic matter properties are discussed.
nucl-thUkr.J.Phys.(2018)·15 citations
04
Two-particle multiplets splitting as a guideline in nucleon pairing estimations
L.T. Imasheva (1) · B.S. Ishkhanov (1,2) · S.V. Sidorov (1) · M.E. Stepanov (1) · T.Yu. Tretyakova (2) ((1) Department of Physics, Lomonosov Moscow State University, (2) Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University)
The ground state multiplet structure for nuclei over the wide range of mass number $A$ was calculated in $δ$ -approximation and different mass relations for pairing energy was analysed in this work. Correlation between the calculated multiplet structure and experimental data offer a guideline in deciding between mass relations for nucleon pairing.
nucl-thnucl-exPhys.Part.Nucl.(2017)·4 citations
05
Anomalous Transport Properties of Dense QCD in a Magnetic Field
Vivian de la Incera🇺🇸
Despite recent advancements in the study and understanding of the phase diagram of strongly interacting matter, the region of high baryonic densities and low temperatures has remained difficult to reach in the lab. Things are expected to change with the planned HIC experiments at FAIR in Germany and NICA in Russia, which will open a window to the high-density-low-temperature segment of the QCD phase map, providing a unique opportunity to test the validity of model calculations that have predicted the formation of spatially inhomogeneous phases with broken chiral symmetry at intermediate-to-high densities. Such a density region is also especially relevant for the physics of neutron stars, as they have cores that can have several times the nuclear saturation density. On the other hand, strong magnetic fields, whose presence is fairly common in HIC and in neutron stars, can affect the properties of these exotic phases and lead to signatures potentially observable in these two settings. In this paper, I examine the anomalous transport properties produced by the spectral asymmetry of the lowest Landau level (LLL) in a QCD-inspired NJL model with a background magnetic field that exhibits chiral symmetry breaking at high density via the formation of a Dual Chiral Density Wave (DCDW) condensate. It turns out that in this model the electromagnetic interactions are described by the axion electrodynamics equations and there is a dissipationless Hall current.
nucl-thcond-mat.mtrl-scicond-mat.str-elhep-phJ.Phys.Conf.Ser.(2017)·1 citation
06
Low-energy $η$ -nucleon interaction studied with $η$ photoproduction off the deuteron
S. X. Nakamura (1, 2)🇯🇵 · H. Kamano (3,4)🇯🇵 · T. Ishikawa (5,6) ((1) Osaka Univ., (2) Univ. Cruzeiro do Sul, (3) KEK, (4) J-PARC, (5) ELPH, (6) Tohoku Univ.)🇯🇵
We develop a reaction model for $η$ photoproduction off the deuteron ( $γ d \to η p n$ ), and study the reaction at a special kinematics, where the photon beam energy is $\sim 0.94$ GeV and the scattered proton is detected at $\sim 0^{\circ}$ , for the purpose of determining the $η$ -nucleon scattering length ( $a_{η N}$ ) and effective range ( $r_{η N}$ ). In this kinematics, the $η$ -nucleon elastic rescattering is significantly enhanced while other background mechanisms being suppressed. We show that a ratio $R$ , the $γ d \to η p n$ cross section divided by the $γ p \to η p$ cross section convoluted with the proton momentum distribution in the deuteron, has a very good resolving power of $a_{η N}$ and $r_{η N}$ . We conclude that the $R$ data with 5% error, binned in 1 MeV width of the $η$ -neutron invariant mass, can determine $Re [a_{η N}]$ ( $Re [r_{η N}]$ ) at the precision of $\sim \pm$ 0.1 fm ( $\sim \pm$ 0.5 fm), significantly narrowing down the previously estimated ranges of the parameters. To arrive at the conclusion, it is essential to use the $γ d \to η p n$ reaction model equipped with elementary amplitudes that are well constrained by $π N$ and $γ N$ reaction data through a sophisticated coupled-channels analysis. This result strongly motivates the Research Center for Electron Photon Science (ELPH) at Tohoku University to measure $R$ .
nucl-thhep-exhep-phnucl-exPRC(2017)·16 citations
07
Shape-phase transitions in odd-mass $γ$ -soft nuclei with mass $A \approx 130$
K. Nomura · T. Nikšić · D. Vretenar
Quantum phase transitions between competing equilibrium shapes of nuclei with an odd number of nucleons are explored using a microscopic framework of nuclear energy density functionals and a particle-boson core coupling model. The boson Hamiltonian for the even-even core nucleus, as well as the spherical single-particle energies and occupation probabilities of unpaired nucleons, are completely determined by a constrained self-consistent mean-field calculation for a specific choice of the energy density functional and pairing interaction. Only the strength parameters of the particle-core coupling have to be adjusted to reproduce a few empirical low-energy spectroscopic properties of the corresponding odd-mass system. The model is applied to the odd-A Ba, Xe, La and Cs isotopes with mass $A \approx 130$ , for which the corresponding even-even Ba and Xe nuclei present a typical case of $γ$ -soft nuclear potential. The theoretical results reproduce the experimental low-energy excitation spectra and electromagnetic properties, and confirm that a phase transition between nearly spherical and $γ$ -soft nuclear shapes occurs also in the odd-A systems.
nucl-thnucl-exPRC(2017)·44 citations
08
$K^{-}$ - nuclear states: Binding energies and widths
J. Hrtánková🇨🇿 · J. Mareš🇨🇿
$K^{-}$ optical potentials relevant to calculations of $K^{-}$ nuclear quasi-bound states were developed within several chiral meson-baryon coupled-channel interaction models. The applied models yield quite different $K^{-}$ binding energies and widths. Then, the $K^{-}$ multinucleon interactions were incorporated by a phenomenological optical potential fitted recently to kaonic atom data. Though the applied $K^{-}$ interaction models differ significantly in the $K^{-} N$ subthreshold region, our self-consistent calculations of kaonic nuclei across the periodic table lead to conclusions valid quite generally. Due to $K^{-}$ multinucleon absorption in the nuclear medium the calculated widths of $K^{-}$ nuclear states are sizable, $Γ_{K^{-}} \geq 90$ MeV, and exceed substantially their binding energies in all considered nuclei.
nucl-thPRC(2017)·40 citations

Affiliations

first authorsco-authorsvia INSPIRE