Nuclear Theory·nucl-th

Tue·Sep 25, 2018Tuesday·September 25, 2018

14 papers—8 primary·6 cross-listed

01
Production of new neutron-rich heavy nuclei with $Z = 56 - 80$ in the multinucleon transfer reactions of $^{136}$ Xe+ $^{198}$ Pt
Cheng Li🇨🇳 · Fan Zhang · Xinxin Xu🇨🇳 · Jingjing Li🇨🇳 · Gen Zhang🇨🇳 · Bing Li🇨🇳 · Cheikh A.T. Sokhna🇨🇳 · Zhishuai Ge🇨🇳 · Peiwei Wen🇨🇳 · Feng-Shou Zhang🇨🇳
The multinucleon transfer reactions in collisions of $^{136}$ Xe+ $^{198}$ Pt at incident energies $E_{lab} =$ 5.25, 6.20, 7.98, 10.0, and 15.0 MeV/nucleon are investigated by using the improved quantum molecular dynamics model. It is found that 6.20 MeV/nucleon is the optimal incident energy for producing the neutron-rich heavy nuclei. About 80 unknown neutron-rich nuclei might be produced in this reaction with cross sections from 10 $^{- 6}$ to 10 $^{- 2}$ mb. The angular distributions of the neutron-rich isotopes are predicted.
nucl-thPRC(2019)·32 citations
02
Quantum and Coulomb repulsion effects on the bubble structures in $^{204, 206}$ Hg
X. Y. Wu🇨🇳 · J. Xiang
The decreasing proton and charge densities from around 5.0 fm towards the center of $^{204, 206}$ Hg are investigated by a covariant density functional theory at the beyond mean-field level.The charge-density difference between $^{208}$ Pb and $^{204}$ Hg is improved significantly and a central depression is still visible in the ground-state density of $^{204, 206}$ Hg when the dynamic correlations associated with symmetry restoration and shape mixing are taken into account. For the $0_{2}^{+}$ and $2_{1}^{+}$ excited states of $^{204, 206}$ Hg, their densities remain decreasing from 5.0 fm to around 2.0 fm, but become flat in the interior region. The results show that the bubble structure in $^{204, 206}$ Hg within 2.0 fm is mainly attributed to the quantum effect, while that beyond 2.0 fm is formed by the Coulomb repulsion.
nucl-thPRC(2018)·5 citations
03
Resonances of unbound quantum many-body systems of nuclei
B. S. Hu🇨🇳 · Q. Wu🇨🇳 · Z. H. Sun🇨🇳 · F. R. Xu🇨🇳
Resonance is a general phenomenon which can happen in classic or quantum systems. An unbound many-body quantum system can undergo a self-resonant process. It has long been a challenge how to describe unbound many-body quantum systems in resonances. In this paper, we develop a novel first-principles method that is capable of describing resonant quantum systems. We exploit, for the first time, the advanced in-medium similarity renormalization group (IMSRG) in the complex-energy Gamow-Berggren representation with resonance and non-resonant continuum. The ab initio Gamow IMSRG has broad applications, such as, to the electromagnetic-interaction systems of atoms, molecules or quantum dots, and strong-interaction atomic nuclei. In the present work, we apply the method to loosely bound or unbound nuclear systems. Carbon and oxygen isotopes have been investigated with an optimized chiral effective field theory potential. The resonant states observed in neutron-rich 22O and 24O are well reproduced. The loose halo structure of the Borromean nucleus 22C is clearly seen by the density calculation, in which the continuum s-waves play a crucial role. Further, we predict low-lying resonant excited states in 22C. This method provides rigorous and tractable theoretical calculations for weakly-bound or unbound open quantum systems.
nucl-thcond-mat.str-elnucl-exphysics.opticsJ. Phys. G: Nucl. Part. Phys. 46 (2019) 1…·1 citation
04
Anomalous internal conversion - the key to understanding the 209Bi riddle
F. F. Karpeshin · M.B.Trzhaskovskaya🇷🇺
Theory of anomalous internal conversion is developed, and extended for the description of the hyperfine splitting. Experimental data on the hyperfine splitting in the H- and Li-like heavy ions of 209Bi are analyzed in terms of the Bohr-Weisskopf effect. Agreement with the theory is achieved, scheduling light on the structure of the magnetization distribution over the nuclear volume.
nucl-thPhys.Atom.Nucl.(2018)·6 citations
05
Forward-backward multiplicity fluctuations in ultra-relativistic nuclear collisions with wounded quarks and fluctuating strings
Martin Rohrmoser🇵🇱 · Wojciech Broniowski🇵🇱
We analyze a generic model where wounded quarks are amended with strings in which both end-point positions fluctuate in spatial rapidity. With the assumption that the strings emit particles independently of one another and with a uniform distribution in rapidity, we are able to analyze the model semi-analytically, which allows for its detailed understanding. Using as a constraint the one-body string emission functions obtained from the experimental data for collisions at $s_{N N} = 200$ GeV, we explore the two-body correlations for various scenarios of string fluctuations. We find that the popular measures used to quantify the longitudinal fluctuations are limited with upper and lower bounds and assume close values for the most likely models of the end-point distributions, which may explain why various approaches yield here very similar results.
nucl-thnucl-exPRC(2019)·11 citations
06
Skyrme-RPA study of charged-current neutrino opacity in hot and dense supernova matter
Alan A. Dzhioev🇷🇺 · Gabriel Martínez-Pinedo🇩🇪
Neutrino emission and their transport of energy to the supernova shock region are sensitive to the physics of hot and dense nuclear matter, which is a complex problem due to the strong correlations induced by nuclear forces. We derive charged-current opacities for electron neutrinos and antineutrinos in supernova matter using a self-consistent approach based on the Skyrme effective interaction. We include a mean field energy shift due to nuclear interaction and corrections due to RPA correlations. A complete treatment of the full Skyrme interaction, including a spin-orbit term, is given. To test the effect of RPA corrections, neutrino and antineutrino opacities are computed using different Skyrme parametrizations consistent with a number of infinite matter constraints.
nucl-thEPJ Web Conf.(2018)·5 citations
07
$K ˉ D ˉ N$ molecular state as a " $uu d s c ˉ$ pentaquark" in a three-body calculation
Junko Yamagata-Sekihara🇯🇵 · Takayasu Sekihara🇯🇵
We predict a new three-body hadronic molecule composed of antikaon $K ˉ$ , anticharm meson $D ˉ$ , and nucleon $N$ with spin/parity $J^{P} = 1/ 2^{+}$ and isospin $I = 1/2$ . This state behaves like an explicit pentaquark state because its minimal quark configuration is $uu d s c ˉ$ or $u dd s c ˉ$ . Owing to the attraction between every pair of two hadrons, in particular the $K ˉ D ˉ$ attraction which dynamically generates $D_{s 0} (2317)^{-}$ and $K ˉ N$ attraction which dynamically generates $Λ (1405)$ , the $K ˉ D ˉ N$ system is bound, and its eigenenergy is calculated as $3244 - 17 i$ MeV in a nonrelativistic three-body potential model. We discuss properties of this $K ˉ D ˉ N$ quasibound state which emerge uniquely in three-body dynamics.
nucl-thhep-phnucl-exPRC(2019)·4 citations
08
The microscopic mechanism behind the fission-barrier asymmetry (II): The rare-earth region $50 < Z < 82$ and $82 < N < 126$
T. Ichikawa🇯🇵 · P. Möller🇺🇸
It is well known that most actinides fission into fragments of unequal size. The first attempt to understand this difference suggested that division leading to one of the fragments being near doubly magic $^{132}$ Sn is favored by gain in binding energy. After the Strutinsky shell-correction method was developed an alternative idea that gained popularity was that the fission saddle might be lower for mass-asymmetric shapes and that this asymmetry was preserved until scission. Recently it was observed [Phys. Rev. Lett. {\bf 105} (2010) 252502] that $^{180}$ Hg preferentially fissions asymmetrically in contradiction to the fragment-magic-shell expectation which suggested symmetric division peaked around $^{90}$ Zr, with its magic neutron number $N = 50$ , so it was presented as a "new type of asymmetric fission". However, in a paper [Phys. Lett. 34B (1971) 349] a "simple" microscopic mechanism behind the asymmetry of the actinide fission saddle points was proposed to be related the coupling between levels of type [40 $ΛΩ$ ] and [51 $ΛΩ$ ]. The paper then generalizes this idea and made the remarkable prediction that analogous features could exist in other regions. In particular it was proposed that in the rare-earth region couplings between levels of type [30 $ΛΩ$ ] and [41 $ΛΩ$ ] would favor mass-asymmetric outer saddle shapes. In this picture the asymmetry of $^{180}$ Hg is not a "new type of asymmetric fission" but of analogous origin as the asymmetry of actinide fission. This prediction has never been cited in the discussion of the recently observed fission asymmetries in the "new region of asymmetry", in nuclear physics also referred to as the rare-earth region. We show by detailed analysis that the mechanism of the saddle asymmetry in the sub-Pb region is indeed the one predicted half a century ago.
nucl-thnucl-exPLB(2019)·34 citations
09
Magnetic field-dependence of the neutral pion mass in the linear sigma model coupled to quarks: The weak field case
Alejandro Ayala🇲🇽 · Ricardo L. S. Farias🇧🇷 · S. Hernandez-Ortiz🇲🇽 · Luis A. Hernandez🇲🇽 · D. Manreza Paret🇲🇽 · R. Zamora🇨🇱
We compute the neutral pion mass dependence on a magnetic field in the weak field approximation at one-loop order. The calculation is carried out within the linear sigma model coupled to quarks and using Schwinger's proper-time representation for the charged particle propagators. We find that the neutral pion mass decreases with the field strength provided the boson self-coupling magnetic field corrections are also included. The calculation should be regarded as the setting of the trend for the neutral pion mass as the magnetic field is turned on.
↳ hep-phhep-thnucl-thPRD(2018)·67 citations
10
Charged-current scattering off $^{16}$ O nucleus as a detection channel for supernova neutrinos
Ken'ichiro Nakazato🇯🇵 · Toshio Suzuki🇯🇵 · Makoto Sakuda🇯🇵
Event spectra of the neutrino- $^{16}$ O charged-current reactions in Super-Kamiokande are evaluated for a future supernova neutrino burst. Since these channels are expected to be useful for diagnosing a neutrino spectrum with high average energy, the evaluations are performed not only for an ordinary supernova neutrino model but also for a model of neutrino emission from a black-hole-forming collapse. Using shell model results, whose excitation energies are consistent with the experimental data, the cross sections of the $^{16}$ O( $ν_{e}, e^{-}$ )X and $^{16}$ O( $ν ˉ_{e}, e^{+}$ )X reactions for each nuclear state with a different excitation energy are employed in this study. It is found that, owing to the components of the reaction with higher excitation energy, the event spectrum becomes 4-7 MeV softer than that in the case without considering the excitation energies. In addition, a simplified approach to evaluate the event spectra is proposed for convenience and its validity is examined.
↳ astro-ph.HEhep-phnucl-thPTEP(2018)·24 citations
11
Effect of limited statistics on higher order cumulants measurement in heavy-ion collision experiments
Ashish Pandav🇮🇳 · Debasish Mallick🇮🇳 · Bedangadas Mohanty🇮🇳
We have studied the effect of limited statistics of data on measurement of the different order of cumulants of net-proton distribution assuming that the proton and antiproton distributions follow Possionian and Binomial distributions with initial parameters determined from experimental results for two top center of mass energies ( $s_{NN} = 200$ and $62.4$ GeV) in most central ( $0 - 5$ %) Au $+$ Au collisions at Relativistic Heavy Ion Collider (RHIC). In this simulation, we observe that the central values for higher order cumulants have a strong dependence on event sample size and due to statistical randomness the central values of higher order cumulants could become negative. We also present a study on the determination of the statistical error on cumulants using delta theorem, bootstrap and sub-group methods and verified their suitability by employing a Monte Carlo procedure. Based on our study we find that the bootstrap method provides a robust way for statistical error estimation on high order cumulants. We also present the exclusion limits on the minimum event statistics needed for determination of cumulants if the signal strength (phase transition or critical point) is at a level of $5$ % and $10$ % above the statistical level. This study will help the experiments to arrive at the minimum required event statistics and choice of proper method for statistical error estimation for high order cumulant measurements.
↳ nucl-exhep-exnucl-thNPA(2019)·28 citations
12
Strange Nuclear Physics from QCD on Lattice
Takashi Inoue (for HAL QCD Collaboration)🇯🇵
We study single-particle potential of Lambda, Sigma, and Xi hyperons in nucleonic matter starting from the fundamental theory of the strong interaction, QCD. First we carry out a lattice QCD numerical simulation, and extract baryon-baryon interactions from QCD by means of the HAL QCD method. We employ a full QCD gauge configuration ensemble at almost physical point so that we can study the physical world, hence mass of hadrons are nearly physical, for example, pion mass is 146 MeV, kaon mass is 525 MeV, and nucleon mass is 958 MeV. Then, we apply the obtained hyperon interactions to the Brueckner-Hartree-Fock many-nucleon theory, and calculate single-particle potential of hyperons in nucleonic matter U_{Y}(k). We obtain for hyperons stopping in the symmetric nuclear matter at the normal nuclear matter density, U_{Lambda}(0)=-28 MeV, U_{Sigma}(0)=+15 MeV, and U_{Xi}(0)=-4 MeV with a statistical error about +/- 2 MeV associated with our Monte Carlo simulation. These results are qualitatively compatible with values suggested from hypernuclear experiments. This success is remarkable and very encouraging since this proves that our approach to strange nuclear physics starting from QCD is essentially correct.
↳ hep-lathep-phnucl-exnucl-thAIP Conf.Proc.(2019)·47 citations
13
Efimov states of three unequal bosons in non-integer dimensions
E.R. Christensen🇩🇰 · A.S. Jensen🇩🇰 · E. Garrido🇪🇸
The Efimov effect for three bosons in three dimensions requires two infinitely large $s$ -wave scattering lengths. We assume two identical particles with very large scattering lengths interacting with a third particle. We use a novel mathematical technique where the centrifugal barrier contains an effective dimension parameter, which allows efficient calculations precisely as in ordinary three spatial dimensions. We investigate properties and occurrence conditions of Efimov states for such systems as functions of the third scattering length, the non-integer dimension parameter, mass ratio between unequal particles, and total angular momentum. We focus on the practical interest of the existence, number of Efimov states and their scaling properties. Decreasing the dimension parameter from $3$ towards $2$ the Efimov effect and states disappear for critical values of mass ratio, angular momentum and scattering length parameter. We investigate the relations between the four variables and extract details of where and how the states disappear. Finally, we supply a qualitative relation between the dimension parameter and an external field used to squeeze a genuine three dimensional system.
↳ physics.atm-clusnucl-thFew Body Syst.(2018)·11 citations
14
Deciphering the coalescence behavior of Coulomb-Schrödinger atomic wave functions from an operator product expansion
Yingsheng Huang🇨🇳 · Yu Jia🇨🇳 · Rui Yu🇨🇳
We revisit the coalescence behavior of the atomic Schrödinger wave functions from the angle of an operator product expansion (OPE) within the nonrelativistic Coulomb-Schrödinger effective field theory. We take the electron-nucleus coalescence as an explicit example to demonstrate our formalism, where the celebrated Kato's cusp condition can be easily reproduced. An exact OPE relation is rigorously proved to all orders in perturbation theory. Our approach can be readily extended to ascertain the multi-particle coalescence behaviors of atomic wave functions, as well as to take relativistic effects into account.
↳ hep-phnucl-thphysics.atom-phphysics.chem-phPRA(2025)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE