Nuclear Theory·nucl-th

Friday·January 10, 2020

11 papers—6 primary·5 cross-listed

01
[Submitted on 8 Jan 2020]
Partonic transport model application to heavy flavor
Weiyao Ke🇺🇸
Heavy-flavor particles are excellent probes of the properties of the hot and dense nuclear medium created in the relativistic heavy-ion collisions. Heavy-flavor transport coefficients in the quark-gluon plasma (QGP) stage of the collisions are particularly interesting, as they contain important information on the strong interaction at finite temperatures. Studying the heavy-flavor evolution in a dynamically evolving medium requires a comprehensive multi-stage modeling approach of both the medium and the probes, with an accurate implementation of the physical ingredients to be tested. For this purpose, I have developed a new partonic transport model (Linear-Boltzmann-plus-Diffusion-Transport-Model) LIDO and applied it to heavy quark propagation inside a QGP. The model has an improved implementation of parton in-medium bremsstrahlung and a flexible treatment of the probe-medium interactions, combining both large angle scatterings and diffusion processes. The model is then coupled to a high-energy event-generator, a hydrodynamic medium evolution and a hadronic transport model. Finally, applying a Bayesian analysis, I extract the heavy quark transport coefficients from a model-to-data comparison. The results, with uncertainty quantification, are found to be consistent with earlier extraction of the light-quark transport coefficients at high momentum and with first-principle calculations of the heavy flavor diffusion constant at low momentum.
Comments:
Ph.D. dissertation; 203 pages, 61 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2001.02766 [pdf]
4 citations
02
[Submitted on 9 Jan 2020]
An {\it ab-initio} Gamow shell model approach with a core
B. S. Hu · Q. Wu · J. G. Li · Y. Z. Ma · Z. H. Sun · N. Michel · F. R. Xu
Gamow shell model (GSM) is usually performed within the Woods-Saxon (WS) basis in which the WS parameters need to be determined by fitting experimental single-particle energies including their resonance widths. In the multi-shell case, such a fit is difficult due to the lack of experimental data of cross-shell single-particle energies and widths. In this paper, we develop an {\it ab-initio} GSM by introducing the Gamow Hartree-Fock (GHF) basis that is obtained using the same interaction as the one used in the construction of the shell-model Hamiltonian. GSM makes use of the complex-momentum Berggren representation, then including resonance and continuum components. Hence, GSM gives a good description of weakly bound and unbound nuclei. Starting from chiral effective field theory and employing many-body perturbation theory (MBPT) (called nondegenerate $Q^$ -box folded-diagram renormalization) in the GHF basis, a multi-shell Hamiltonian ({\it sd-pf} shells in this work) can be constructed. The single-particle energies and their resonance widths can also been obtained using MBPT. We investigated $^{23 - 28}$ O and $^{23 - 31}$ F isotopes, for which multi-shell calculations are necessary. Calculations show that continuum effects and the inclusion of the {\it pf} shell are important elements to understand the structure of nuclei close to and beyond driplines.
Comments:
Accept by Physics Letters B
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2001.02832 [pdf]
PLB(2020)·40 citations
03
[Submitted on 9 Jan 2020]
Dynamics of the linear-chain alpha cluster in microscopic time-dependent relativistic density functional theory
Z. X. Ren · P. W. Zhao · J. Meng
The time-dependent covariant density functional theory in 3D lattice space has been developed and applied to investigate the microscopic dynamics of the linear-chain cluster states for carbon isotopes in the reactions $^{4}$ He $+^{8}$ Be and $^{4}$ He $+^{10}$ Be without any symmetry assumptions. By examining the density distribution and its time evolutions, the structure and dynamics of the linear-chain states are analyzed, and the quasiperiodic oscillations of the clusters are revealed. For $^{4}$ He $+^{8}$ Be, the linear-chain states evolve to a triangular configuration and then to a more compact shape. In contrast, for $^{4}$ He $+^{10}$ Be, the lifetime of the linear-chain states is much more prolonged due to the dynamical isospin effects by the valence neutrons which slow down the longitudinal oscillations of the clusters and persist the linear-chain states. The dependence of the linear chain survival time and dynamical isospin effects on impact parameters have been illustrated as well.
Comments:
14 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2001.02834 [pdf]
PLB(2020)·35 citations
04
[Submitted on 9 Jan 2020]
Temperature effects on the neutron matter equation of state obtained from chiral effective field theory
F. Sammarruca🇺🇸 · R. Machleidt🇺🇸 · R. Millerson🇺🇸
Temperature effects on the neutron matter equation of state are investigated in the framework of chiral effective field theory. Latest, state-of-the-art chiral two-nucleon forces are applied from third to fifth order in the chiral expansion together with chiral three-nucleon forces, allowing for a determination of the truncation error of the theoretical predictions. The thermodynamic quantities considered include the chemical potential, the internal energy, the entropy, and the free energy. In general, good order-by-order convergence of all predictions is observed. As to be expected, temperature effects are largest at low density. The temperature dependence of the chiral three-nucleon force turns out to be weak.
Comments:
9 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2001.02845 [pdf]
Mod.Phys.Lett.A(2020)·7 citations
05
[Submitted on 9 Jan 2020]
Theoretical Analysis of Double Differential Cross Section of Proton, Deuteron and Triton for $p +^{7}$ Li Reaction at 14 MeV
Jiaqi Hu · Xiaojun Sun · Jingshang Zhang · Sheng Wang · Sheng Wang · Yinlu Han
Based on the statistical theory of light nucleus reactions (STLN), the description of the complicated emission processes of proton and light composite charged particles are further improved through considering the effects of Coulomb barriers both in incident and different outgoing reaction channels. And the analysis of the reaction channels including the sequential and simultaneous emission processes for $p +^{7}$ Li reaction is performed in detail. So the partial spectra of all of outgoing particles are also obtained for different reaction processes. The calculated double differential cross sections of total outgoing proton, deuteron and triton at $E_{p} = 14$ MeV agree well with the available experimental data for different outgoing angles. The ENDF-6 formatted data, which includes all of the reaction cross sections, elastic angular distributions, double differential cross sections of nucleon and light composite charged particles for $p +^{7}$ Li reaction, are also obtained by PUNF code.
Comments:
34 pages, 16 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2001.02891 [pdf]
PRC(2020)·6 citations
06
[Submitted on 9 Jan 2020]
Breakdown of the tensor component in the Skyrme energy density functional
J. M. Dong · X. L. Shang
The tensor force, as an important component of strong nuclear force, generates a variety of intriguing effects ranging from few-body systems to neutron stars. It is responsible for the nucleon-nucleon correlation beyond mean-field approximation, and is accordingly proved to play no role in the standard Skyrme energy density functionals in the present work. Therefore, the Skyrme's original tensor interaction that is extensively-employed presently is invalid. As an alternative strategy, we introduced a central interaction, i.e., the $σ_{1} \cdot σ_{2}$ term, to improve the description of experimental single-particle structure, and to address its effect, we established two Skyrme interactions IMP1 and IMP2 complemented by the calibrated charge-violating interactions. The central $σ_{1} \cdot σ_{2}$ interaction turns out to substantially improve the description of shell evolution in Sn isotopes and $N = 82$ isotones.
Comments:
6 pages, 1 figure, Phys. Rev. C 101, 014305 (2020)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2001.02937 [pdf]
PRC(2020)·10 citations
07
[Submitted on 8 Jan 2020] (cross-list from hep-lat)
Quantum delocalization of strings with boundary action in Yang-Mills theory
A. S. Bakry🇨🇳 · M. A. Deliyergiyev🇨🇳 · A. A. Galal🇪🇬 · A. M. Khalaf🇪🇬 · M. Khalil William
The width of the quantum delocalization of the QCD strings is investigated in effective string models beyond free Nambu-Goto approximation. We consider two Lorentzian-invariant boundary-terms in the Lüscher-Weisz string action in addition to self-interaction term equivalent to two loop order in the (NG) string action. The geometrical terms which realize the possible rigidity of the QCD string is scrutinized as well. We perform the numerical analysis on the 4-dim pure $S U (3)$ Yang-Mills lattice gauge theory at two temperature scales near deconfinement point. The comparative study with this QCD string model targets the width of the energy profile of a static quark-antiquark system for color sources separation $0.5 \leq R \leq 1.2$ fm. We find the inclusion of rigidity properties and symmetry effects of the boundary action into the string paradigm to reproduce a good match with the profile of the Mont-Carlo data of QCD flux-tube on this distance scale.
Comments:
23 pages, 12 Figures, 13 Tables
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2001.02392 [pdf]
7 citations
08
[Submitted on 8 Jan 2020] (cross-list from nucl-ex)
Systematics of direct- $α$ production with weakly and strongly bound projectiles
V. V. Parkar · V. Jha · S. Kailas
The production of $α$ -particles in reactions using both the strongly and weakly bound projectiles at energies around the Coulomb barrier show several interesting features. To understand these, the role of various reaction mechanisms responsible for $α$ -production, such as non-capture breakup, capture of only one of the fragments subsequent to projectile breakup and their contribution to reaction cross sections have been investigated. A systematic study of the $α$ -particle production based on available data for various projectile target systems have been performed and a classification based on projectile type is obtained.
Comments:
7 pages, 5 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2001.02448 [pdf]
2 citations
09
[Submitted on 8 Jan 2020] (cross-list from hep-ph)
Lack of Debye and Meissner screening in strongly magnetized quark matter at intermediate densities
Bo Feng🇨🇳 · Efrain J. Ferrer🇺🇸 · Israel Portillo🇺🇸
We study the static responses of cold quark matter in the intermediate baryonic density region (characterized by a chemical potential $μ$ ) in the presence of a strong magnetic field. We consider in particular, the so-called Magnetic Dual Chiral Density Wave (MDCDW) phase, which is materialized by an inhomogeneous condensate formed by a particle-hole pair. It is shown, that the MDCDW phase is more stable in the weak-coupling regime than the one considered in the magnetic catalysis of chiral symmetry braking phenomenon (MC $χ$ SB) and even than the chiral symmetric phase that was expected to be realized at sufficiently high baryonic chemical potential. The different components of the photon polarization operator of the MDCDW phase in the one-loop approximation are calculated. We found that in the MDCDW phase there is no Debye screening neither Meissner effect in the lowest-Landau-level approximation. The obtained Debye length depends on the amplitude $m$ and modulation $b$ of the inhomogeneous condensate and it is only different from zero if the relation $∣ μ - b ∣ > m$ holds. But, we found that in the region of interest this inequality is not satisfied. Thus, no Debye screening takes place under those conditions. On the other hand, since the particle-hole condensate is electrically neutral, the U(1) electromagnetic group is not broken by the ground state and consequently there is no Meissner effect. These results can be of interest for the astrophysics of neutron stars.
Comments:
18 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2001.02617 [pdf]
PRD(2020)·14 citations
10
[Submitted on 9 Jan 2020] (cross-list from nucl-ex)
Non-monotonic energy dependence of net-proton number fluctuations
STAR Collaboration: J. Adam · L. Adamczyk · J. R. Adams · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · I. Alekseev · D. M. Anderson · A. Aparin · E. C. Aschenauer · M. U. Ashraf and 346 other authors
Non-monotonic variation with collision energy ( $s_{NN}$ ) of the moments of the net-baryon number distribution in heavy-ion collisions, related to the correlation length and the susceptibilities of the system, is suggested as a signature for the Quantum Chromodynamics (QCD) critical point. We report the first evidence of a non-monotonic variation in kurtosis times variance of the net-proton number (proxy for net-baryon number) distribution as a function of \rootsnn with 3.1 $σ$ significance, for head-on (central) gold-on-gold (Au+Au) collisions measured using the STAR detector at RHIC. Data in non-central Au+Au collisions and models of heavy-ion collisions without a critical point show a monotonic variation as a function of $s_{NN}$ .
Comments:
12 Pages, 9 Figures and 5 Tables (published version)
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2001.02852 [pdf]
PRL(2021)·377 citations
11
[Submitted on 9 Jan 2020] (cross-list from hep-ph)
Observed $Ω_{b}$ spectrum and meson-baryon molecular states
Wei-Hong Liang🇨🇳 · E. Oset🇨🇳
We observe that four peaks seen in the high energy part of the $Ω_{b}$ spectrum of the recent LHCb experiment are in remarkable agreement with predictions made for molecular $Ω_{b}$ states stemming from the meson-baryon interaction, with an approach that applied to the $Ω_{c}$ states gave rise to three states in good agreement with experiment in masses and widths. While the statistical significance of the peaks prevents us from claims of states at the present time, the agreement found should be an incentive to look at this experiment with increased statistics to give an answer to this suggestive idea.
Comments:
8 pages, 2 tables; V2: New section and discussion added, references added, version to appear in Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2001.02929 [pdf]
PRD(2020)·23 citations

Affiliations

first authorsco-authorsvia INSPIRE