Nuclear Theory·nucl-th

Tuesday·March 20, 2018

12 papers—9 primary·3 cross-listed

01
Probable Decay Modes at Limits of Nuclear Stability of the Superheavy Nuclei
M. Bhuyan
The modes of decay for the even-even isotopes of superheavy nuclei of Z = 118 and 120 with neutron number $160 \leq N \leq 204$ are investigated in the framework of the axially deformed relativistic mean field model. The asymmetry parameter $η$ and the relative neutron-proton asymmetry of the surface to the center ( $R_{η}$ ) are estimated from the ground state density distributions of the nucleus. We analyze the resulting asymmetry parameter $η$ and the relative neutron-proton asymmetry $R_{η}$ of the density play a crucial role in the mode(s) of decay and its half-life. Moreover, the excess neutron richness on the surface facets a superheavy nucleus for $β^{-}$ decays.
nucl-thPhys.Atom.Nucl.(2018)·13 citations
02
Fragment Distribution in Reactions of $^{78, 86}$ Kr+ $^{181}$ Ta
Donghong Zhang · Fengshou Zhang
Within the framework of the isospin-dependent quantum molecular dynamics model along with the GEMINI model, the reaction of $^{86}$ Kr+ $^{181}$ Ta at 80,120 and 160 MeV/nucleon and the reaction of $^{78}$ Kr+ $^{181}$ Ta at 160 MeV/nucleon are studied, and the production cross sections of the generated fragments are calculated. More intermediate and large mass fragments can be produced in the reaction with a large range of impact parameter. The production cross sections of nuclei such as the isotopes of Si and P generally decrease with the increasing incident energy. The isotopes near the neutron drip line are produced more in the neutron-rich system $^{86}$ Kr+ $^{181}$ Ta.
nucl-thCPC(2018)·0 citations
03
Effects of the equation of state on the core-crust interface of slowly rotating neutron stars
L. Tsaloukidis · Ch. Margaritis · Ch.C. Moustakidis
We systematically study the symmetry energy effects of the transition density $n_{t}$ and the transition pressure $P_{t}$ around the crust-core interface of a neutron star in the framework of the dynamical and the thermodynamical method respectively. We employ both the parabolic approximation and the full expansion, for the definition of the symmetry energy. We use various theoretical nuclear models, which are suitable for reproducing the bulk properties of nuclear matter at low densities, close to saturation density as well as the maximum observational neutron star mass. Firstly we derive and present an approximation for the transition pressure $P_{t}$ and crustal mass $M_{crust}$ . Secondly, we explore the effects of the Equation of State (EoS) on a few astrophysical applications which are sensitive to the values of $n_{t}$ and $P_{t}$ including neutron star oscillation frequencies, thermal relaxation of the crust, crustal fraction of the moment of inertia and the r-mode instability window of a rotating neutron star. We found that the above quantities are sensitive mainly on the applied approximation for the symmetry energy (confirming previous results). Furthermore, an additional sensitivity also exists, depending on the used method (dynamical or thermodynamical). The above findings lead us to claim that the determination of the $n_{t}$ and $P_{t}$ must be reliable and accurate before they are used to constrain relevant neutron star properties.
nucl-thastro-ph.HEPRC(2019)·21 citations
04
Vortex-like solutions and internal structures of covariant ideal magnetohydrodynamics
Wojciech Florkowski🇵🇱 · Avdhesh Kumar🇵🇱 · Radoslaw Ryblewski🇵🇱
We discuss a manifestly covariant formulation of ideal relativistic magnetohydrodynamics, which has been recently used in astrophysical and heavy-ion contexts, and compare it to other similar frameworks. We show that the covariant equations allow for stationary vortex-like solutions that represent generalizations of the perfect-fluid solutions describing systems in global equilibrium with rotation. Such solutions are further used to demonstrate that inhomogeneous Maxwell equations, implicitly included in the covariant framework, may generate very large electric charge densities. This suggests that solutions of the covariant formulation may violate in some cases the assumptions of standard ideal magnetohydrodynamics. Furthermore, we show that the flow four-vector and conserved currents obtained in the covariant approach are usually not related to each other, which hinders kinetic-theory interpretation of the obtained results.
nucl-thhep-phEPJA(2018)·8 citations
05
Polar polarization: a new method for polarimetry analysis
D. Izraeli (1)🇮🇱 · I. Mardor (1,2)🇮🇱 · E.O. Cohen (1)🇮🇱 · M. Duer (1)🇮🇱 · T.Y. Izraeli (3) · I. Korover (1,4)🇮🇱 · J. Lichtenstadt (1)🇮🇱 · E. Piasetzky (1) ((1) School of Physics and Astronomy, Tel Aviv University, Tel Aviv 6997801, Israel., (2) Soreq NRC, Yavne 81800, Israel., (3) Guardian Optical Technologies, Derech Hashalom 7, Tel Aviv 6789208, Israel., (4) Department of Physics, NRCN, P.O. Box 9001, Beer-Sheva 8419001, Israel.)🇮🇱
We present a novel analysis method for measurements of polarization transferred in $A (e, e^{'} N)$ experiments, which can be applied to other kinds of polarization measurements as well. In this method the polarization transfer components are presented in spherical coordinates using an efficient likelihood numerical maximization based on an analytic derivation. We also propose a formalism that accounts for multi-parameter models, and which yields a smooth and continuous representation of the data (rather than using standard binning). Applying this method on simulated data generates results with reduced statistical and systematic uncertainties and enables revealing physical information that is lost in standard binning of the data. The obtained results can be compared easily to theoretical models and other measurements. Furthermore, CPU time is significantly reduced using this method.
nucl-thhep-phnucl-exJINST(2018)·2 citations
06
Impact of the $^{7}$ Be( $α, γ$ ) $^{11}$ C reaction on the primordial abundance of $^{7}$ Li
M. Hartos · C. A. Bertulani · Shubhchintak · A. M. Mukhamedzhanov · S. Hou
We calculate the radiative capture cross section for $^{7}$ Be( $α, γ$ ) $^{11}$ C and its reaction rate of relevance for the big bang nucleosynthesis. The impact of this reaction on the primordial $^{7}$ Li abundance is revised including narrow and broad resonances in the pertinent energy region. Our calculations show that it is unlikely that very low energy resonances in $^{11}$ C of relevance for the big bang nucleosynthesis would emerge within a two-body potential model. Based on our results and a comparison with previous theoretical and experimental analyses, we conclude that the impact of this reaction on the so-called "cosmological lithium puzzle" is completely irrelevant.
nucl-thastro-ph.COnucl-exApJ(2018)·11 citations
07
Hadron-Quark Combustion as a Nonlinear, Dynamical System
Amir Ouyed🇨🇦 · Rachid Ouyed🇨🇦 · Prashanth Jaikumar🇺🇸
The hadron-quark combustion front is a system that couples various processes, such as chemical reactions, hydrodynamics, diffusion, and neutrino transport. Previous numerical work has shown that this system is very nonlinear, and can be very sensitive to some of these processes. In these proceedings, we contextualize the hadron-quark combustion as a nonlinear system, subject to dramatic feedback triggered by leptonic weak decays and neutrino transport.
nucl-thastro-ph.HEUniverse(2018)·3 citations
08
Multipole Modes for Triaxially Deformed Superfluid Nuclei
Kouhei Washiyama · Takashi Nakatsukasa
To study shape fluctuations of nuclei in transitional regions, the collective Hamiltonian method has often been employed. We intend to construct the quadrupole collective Hamiltonian with the collective inertial functions given by the local quasiparticle random-phase approximation (QRPA) based on the Skyrme energy density functional. For this purpose, we first construct a practical framework of Skyrme QRPA for triaxial nuclear shapes with the finite amplitude method (FAM). We show quadrupole strength functions for a triaxial superfluid nucleus $^{188}$ Os and the Thouless-Valatin rotational moment of inertia by the local FAM-QRPA for $^{106}$ Pd.
nucl-thnucl-exJPS Conf.Proc.(2018)·4 citations
09
Generic features of the neutron-proton interaction
Y. H. Kim🇫🇷 · M. Rejmund🇫🇷 · P. Van Isacker🇫🇷 · A. Lemasson🇫🇷
We show that fully aligned neutron-proton pairs play a crucial role in the low-energy spectroscopy of nuclei. with valence nucleons in a high-j orbital. Their dominance is valid in nuclei with valence neutrons and protons in different high-j orbitals as well as in N = Z nuclei, where all nucleons occupy the same orbital. We demonstrate analytically this generic feature of the neutron-proton interaction for a variety of systems with four valence nucleons interacting through realistic, effective forces. The dominance of fully aligned neutron-proton pairs results from the combined effect of (i) angular momentum coupling and (ii) basic properties of the neutron-proton interaction.
nucl-thPRC(2018)·6 citations
10
Dynamics of first-order quantum phase transitions in extended Bose-Hubbard model: From density wave to superfluid and vice-versa
Keita Shimizu · Takahiro Hirano · Jonghoon Park · Yoshihito Kuno · Ikuo Ichinose
In this paper, we study the nonequilibrium dynamics of the Bose-Hubbard model with the nearest-neighbor repulsion by using time-dependent Gutzwiller (GW) methods. In particular, we vary the hopping parameters in the Hamiltonian as a function of time, and investigate the dynamics of the system from the density wave (DW) to the superfluid (SF) crossing a first-order phase transition and vice-versa. From the DW to SF, we find scaling laws for the correlation length and vortex density with respect to the quench time. This is a reminiscence of the Kibble-Zurek scaling for continuous phase transitions and contradicts the common expectation. We give a possible explanation for this observation. On the other hand from the SF to DW, the system evolution depends on the initial SF state. When the initial state is the ground-state obtained by the static GW methods, a coexisting state of the SF and DW domains forms after passing through the critical point. Coherence of the SF order parameter is lost as the system evolves. This is a phenomenon similar to the glass transition in classical systems. When the state starts from the SF with small local phase fluctuations, the system obtains a large-size DW-domain structure with thin domain walls.
↳ cond-mat.quant-gasgr-qcnucl-thquant-phNew J.Phys.(2018)·17 citations
11
Exclusive vector meson production at an electron-ion collider
Michael Lomnitz🇺🇸 · Spencer Klein🇺🇸
Coherent exclusive vector meson electroproduction is a key physics channel at an electron-ion collider. It probes the gluon structure of nuclei over a wide range of $Q^{2}$ , and can be used to measure nuclear shadowing and to search for gluon saturation and/or the colored glass condensate. In this paper, we present calculations of the kinematic distributions for a variety of exclusive vector meson final states: the $ρ$ , $ϕ$ , J/ $ψ$ , $ψ^{'}$ and the $Υ$ states. The cross-sections for light and $c c$ mesons are large, while $Υ$ states should be produced in moderate numbers at a medium energy EIC (the proposed U.S. designs) and in large numbers at the LHeC. We investigate the acceptances for these states, as a function of detector rapidity coverage. A large-acceptance detector is needed to cover the full range photon-nucleon collision energies produced at an EIC; a forward detector is required to observe vector mesons from the most energetic photon interactions, and thereby probe gluons at the lowest possible Bjorken- $x$ values.
↳ nucl-exhep-phnucl-thPRC(2019)·53 citations
12
A novel Dual Chiral Density Wave in nuclear matter based on a parity doublet structure
Yusuke Takeda🇯🇵 · Hiroaki Abuki🇯🇵 · Masayasu Harada🇯🇵
We study the Dual Chiral Density Wave (DCDW) in nuclear matter using a hadronic model with the parity doublet structure. We first extend the ordinary DCDW ansatz so as to incorporate the effect of an explicit chiral symmetry breaking. Then via numerically evaluating and minimizing the effective potential, we determine the phase structure. We find, in addition to the ordinary DCDW phase where the space average of the chiral condensate vanishes, a new DCDW phase (sDCDW) with a nonvanishing space average depending on the value of the chiral invariant mass parameter.
↳ hep-phnucl-thPRD(2018)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE