Nuclear Theory·nucl-th

Thursday·December 27, 2018

22 papers—12 primary·10 cross-listed

01
[Submitted on 21 Dec 2018]
Parton distribution functions from scalar light-front parton gas model
Shaoyang Jia🇺🇸 · James P. Vary🇺🇸
We propose an application of a microcanonical ensemble with light-front kinematics to model the phase-space distribution of relativistic constituents of a bound state. These constituents denoted by partons are treated as classical spin-zero particles confined inside the bound state with inter-parton collisions as their only interaction. The microcanonical molecular dynamics ensemble is applied to obtain the phase-space distribution of such a thermodynamic system. We sample this phase-space distribution using Monte Carlo algorithms to obtain the parton distribution functions (PDFs) in scenarios with $3$ , $4$ , and $5$ identical partons. In addition PDFs when a selected number of massless partons are mixed with $3$ massive partons are also presented.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1812.09340 [pdf]
Physica A(2025)·6 citations
02
[Submitted on 22 Dec 2018]
A realistic spectral function model for charged-current quasielastic-like neutrino and antineutrino cross sections on $^{12}$ C
M.V. Ivanov🇧🇬 · A.N. Antonov🇧🇬 · G.D. Megias🇪🇸 · J.A. Caballero🇪🇸 · M.B. Barbaro🇮🇹 · J.E. Amaro🇪🇸 · I. Ruiz Simo🇪🇸 · T.W. Donnelly🇺🇸 · J.M. Udias🇪🇸
A detailed study of charged current quasielastic neutrino and antineutrino scattering cross sections on a $^{12}$ C target with no pions in the final state is presented. The initial nucleus is described by means of a realistic spectral function $S (p, E)$ in which nucleon-nucleon correlations are implemented by using natural orbitals through the Jastrow method. The roles played by these correlations and by final-state interactions are analyzed and discussed. The model also includes the contribution of weak two-body currents in the two-particle two-hole sector, evaluated within a fully relativistic Fermi gas. The theoretical predictions are compared with a large set of experimental data for double-differential, single-differential and total integrated cross sections measured by the MiniBooNE, MINER $ν$ A and T2K experiments. Good agreement with experimental data is found over the whole range of neutrino energies. The results are also in global good agreement with the predictions of the superscaling approach, which is based on the analysis of electron-nucleus scattering data, with only a few differences seen at specific kinematics.
Comments:
14 pages, 12 figures, accepted for publication in Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1812.09435 [pdf]
PRC(2019)·26 citations
03
[Submitted on 22 Dec 2018]
Asymmetric Nuclear Light Clusters In Supernova Matter
Andrey Yudin · Matthias Hempel · Sergei Blinnikov · Dmitriy Nadyozhin · Igor Panov
We explore the appearance of light clusters at high densities of collapsing stellar cores. Special attention is paid to the unstable isotope H4, which was not included in previous studies. The importance of light clusters in the calculation of rates for neutrino matter interaction is discussed. The main conclusion is that thermodynamic quantities are only weakly sensitive to the chemical composition. The change in pressure and hence the direct change in collapse dynamics will be minor. But the change in neutrino heating and neutronization processes can be significant.
Comments:
9 pages, 8 figures. Accepted to MNRAS
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
1812.09494 [pdf]
MNRAS(2019)·13 citations
04
[Submitted on 22 Dec 2018]
How to produce new superheavy nuclei?
K. Siwek-Wilczyńska🇵🇱 · T. Cap🇵🇱 · M. Kowal🇵🇱
Existing experimental facilities limit the possibilities for discovery of new nuclides to those synthesized with cross sections above 100 fb, but the perspectives for future high current accelerators could lower this limit by two orders of magnitude. Therefore, in the present work excitation functions for fusion- $x n$ evaporation reaction channels induced not only by $^{48} C a$ but also by heavier projectiles (usually leading to smaller cross sections) on actinide targets were calculated in the framework of the fusion-by-diffusion (FBD) model. For the first time, in this approach, channels in which a proton ( $p x n$ ) or alpha particle ( $α$ $x n$ ) is evaporated have been included in the first step of the deexcitation cascade. To calculate the synthesis cross sections entry data such as fission barriers, ground-state masses, deformations and shell effects of the superheavy nuclei calculated in a consistent way within the Warsaw macroscopic-microscopic model were used. The only adjustable parameter of the FBD model is the injection point distance $s_{inj}$ and the value determined in our previous analysis of experimental cross sections for the synthesis of superheavy nuclei of Z=114-118 has been used. Excitation functions for the synthesis of selected (cross section above a few fb) new superheavies in the range of atomic numbers 112-120 are presented. Observation of 21 new heaviest isotopes is predicted. A realistic discussion of the FBD model uncertainties is presented for the first time.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1812.09522 [pdf]
PRC(2019)·31 citations
05
[Submitted on 24 Dec 2018]
Pairing in Nuclear Matter and Finite Nuclei
Herbert Müther · Artur Polls
Effects of pairing with isospin $T = 0$ and $T = 1$ are systematically studied in a model, which is based on a realistic nucleon-nucleon interaction and allows to describe the transition from infinite nuclear matter to finite nuclei. Special attention is paid to the development of the spin-orbit term in the mean field of nucleons in finite nuclei. The spin-orbit term yields a drastic suppression of $T = 0$ proton-neutron pairing but does not lead to a complete disappearance in finite nuclei. Arguments are presented, why no clear evidence of $T = 0$ pairing can be observed in the binding energies of finite nuclei.
Comments:
11 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1812.09908 [pdf]
PRC(2019)·9 citations
06
[Submitted on 24 Dec 2018]
Impact of the neutron star crust on the tidal polarizability
J. Piekarewicz · F.J. Fattoyev
The first detection of a binary neutron star merger has opened the brand new era of multimessenger astronomy. This historic detection has been instrumental in providing constraints on the tidal polarizability of neutron stars. In turn, the tidal polarizability has been used to impose limits on stellar radii and ultimately on the equation of state (EOS). The tidal polarizability is also sensitive to the second tidal Love number k2. It is the main purpose of this work to perform a detailed study of k2 which, for a given compactness parameter, encodes the entire sensitivity of the tidal polarizability to the EOS. In particular, we examine the role that the crustal component of the EOS plays in the determination of k2. A set of realistic models of the equation of state that yield an accurate description of the properties of finite nuclei and support neutron stars of two solar masses is used. Given that the tidal polarizability scales as the fifth power of the compactness parameter, a universal relation exists among the tidal polarizability and the compactness parameter that is highly insensitive to the underlying EOS. Thus, besides an extraction of the tidal polarizabilities, a measurement of the individual stellar masses is also required to impact the mass-radius relation. However, we observe a strong sensitivity of k2 to the EOS, particularly to the contribution from the inner crust. Although by itself the tidal polarizability can not contribute to the determination of the mass-radius relation, future detections of binary neutron star mergers are poised to provide significant constraints on both the tidal polarizabilities and masses of the individual stars, and thus ultimately on the mass-radius relation. Yet, subleading corrections to the tidal polarizability are encoded in the second Love number k2 which displays a large sensitivity to the entire (crust-plus-core) EOS.
Comments:
15 pages and 5 figures; submitted to Physical Review C
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
arXiv:
1812.09974 [pdf]
PRC(2019)·68 citations
07
[Submitted on 24 Dec 2018]
Role of fluctuations on the pairing properties of nuclei in the random spacing model
M. A. A. Mamun · C. Constantinou · M. Prakash
The influence of thermal fluctuations on fermion pairing is investigated using a semiclassical treatment of fluctuations. When the average pairing gaps along with those differing by one standard deviation are used, the characteristic discontinuity of the specific heat at the critical temperature $T_{c}$ in the BCS formalism with its most probable gap becomes smooth. This indicates the suppression of a second order phase transition as experimentally observed in nano-particles and several nuclei. Illustrative calculations using the constant spacing model and the recently introduced random spacing model are presented.
Comments:
6 pages, 5 figures, 6th International Workshop on Compound-Nuclear Reactions and Related Topics
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1812.09988 [pdf]
Springer Proc.Phys.(2020)·0 citations
08
[Submitted on 25 Dec 2018]
Fusion barrier distribution and superheavy elements
K. Hagino · T. Tanaka
The barrier distribution, originated from channel coupling effects in heavy-ion fusion reactions, has been extracted experimentally for many systems using either a fusion excitation function or an excitation function of large-angle quasi-elastic scattering. In this article, we discuss an application of the latter method to the $^{48}$ Ca+ $^{248}$ Cm system, which is relevant to hot fusion reactions to synthesize superheavy elements. To this end, we carry out coupled-channels calculations for this system, taking into account the deformation of the target nucleus, and discuss the role of deformation in a formation of evaporation residues.
Comments:
7 pages, 4 figures. A talk given at the XLI Brazilian Meeting on Nuclear Physics, Maresias, Brazil, Sep. 2-6, 2018. To be published in the Journal of Physics: Conference Series
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1812.10040 [pdf]
J.Phys.Conf.Ser.(2019)·3 citations
09
[Submitted on 25 Dec 2018]
Nuclear modification of full jets and jet structure in relativistic nuclear collisions
Ning-Bo Chang🇨🇳 · Guang-You Qin🇨🇳 · Yasuki Tachibana🇺🇸
With our coupled jet-fluid model, we study the nuclear modifications of full jets and jet structures for single inclusive jet and $γ$ -jet events in relativistic heavy-ion collisions. The evolution of full jet showers is studied via a set of coupled transport equations including the effects of collisional energy loss, transverse momentum broadening and medium-induced splitting. The dynamics of the jet energy and momentum deposited into the medium is described by hydrodynamic equations with source terms. Our detailed analysis indicates that collisional absorption (energy loss) tends to narrow the jet shape function while transverse momentum kicks and medium-induced radiations broaden the jet transverse profile. Also, jet-induced flow plays a significant contribution to jet shape function and dominates at large angles away from the jet axis. The final nuclear modification pattern for the jet shape function is a combined effect from various jet-medium interaction mechanisms. Our detailed studies for single inclusive jets and $γ$ -jets for various kinematics indicate that the nuclear modification of jet shape has strong dependence on jet energy and collision energy, and weak dependence on jet flavor (quark or gluon).
Comments:
5 pages, 3 figures, Proceedings of Hard Probes 2018, 30 September-5 October, Aix-Les-Bains, France
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1812.10080 [pdf]
PoS(2018)·0 citations
10
[Submitted on 25 Dec 2018]
Spectroscopy of odd-odd nuclei within the interacting boson-fermion-fermion model based on the Gogny energy density functional
K. Nomura · R. Rodríguez-Guzmán · L. M. Robledo
We present a method to calculate spectroscopic properties of odd-odd nuclei within the framework of the Interacting Boson-Fermion-Fermion Model based on the Gogny energy density functional. The $(β, γ)$ -deformation energy surface of the even-even (boson-)core nucleus, spherical single-particle energies and occupation probabilities of the odd neutron and odd proton, are provided by the constrained self-consistent mean-field calculation within the Hartree-Fock-Bogoliubov method with the Gogny-D1M functional. These quantities are used as a microscopic input to fix most of the parameters of the IBFFM Hamiltonian. Only a few coupling constants for the boson-fermion Hamiltonian and the residual neutron-proton interaction are specifically adjusted to reproduce experimental low-energy spectra in odd-mass and odd-odd nuclei, respectively. In this way, the number of free parameters involved in the IBFFM framework is reduced significantly. The method is successfully applied to the description of the low-energy spectra and electromagnetic transition rates in the odd-odd $^{194, 196, 198}$ Au nuclei.
Comments:
11 pages, 5 figures, 9 tables
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1812.10174 [pdf]
PRC(2019)·17 citations
11
[Submitted on 25 Dec 2018]
Hadron modification in a dense baryonic matter
G. Musulmanbekov🇷🇺
Starting with the Strongly Correlated Quark Model of a hadron structure, SCQM, we demonstrate how the properties of mesons and baryons are modified in a hot and dense nuclear environment. These in-medium modifications can lead to the observable effects in heavy ion collisions, such as enhancement of strangeness and dropping vector meson masses.
Comments:
7 pages, 4 figures. Presented at Baldin ISHEPP XXIV, September 17-22, 2018
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1812.10177 [pdf]
EPJ Web Conf.(2019)·1 citation
12
[Submitted on 26 Dec 2018]
Zemach moments and radii of 2,3H and 3,4He
N. Nevo Dinur · O.J. Hernandez · S. Bacca · N. Barnea · C. Ji · S. Pastore · M. Piarulli · R. B. Wiringa
We present benchmark calculations of Zemach moments and radii of 2,3H and 3,4He using various few-body methods. Zemach moments are required to interpret muonic atom data measured by the CREMA collaboration at the Paul Scherrer Institute. Conversely, radii extracted from spectroscopic measurements can be compared with ab initio computations, posing stringent constraints on the nuclear model. For a given few-body method, different numerical procedures can be applied to compute these quantities. A detailed analysis of the numerical uncertainties entering the total theoretical error is presented. Uncertainties from the few-body method and the calculational procedure are found to be smaller than the dependencies on the dynamical modeling and the single nucleon inputs, which are found to be <= 2%. When relativistic corrections and two-body currents are accounted for, the calculated moments and radii are in very good agreement with the available experimental data.
Comments:
11 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1812.10261 [pdf]
PRC(2019)·34 citations

Affiliations

first authorsco-authorsvia INSPIRE