Nuclear Theory·nucl-th

Wednesday·September 12, 2018

12 papers—6 primary·6 cross-listed

01
[Submitted on 11 Sept 2018]
Microscopic description of structural evolution in Pd, Xe, Ba, Nd, Sm, Gd and Dy isotopes
Tabassum Naz · G. H. Bhat · S. Jehangir · Shakeb Ahmad · J. A. Sheikh
Aiming to understand the role of triaxiality and the evolution of the ground state nuclear shapes, we have carried out a microscopic study for a series of chains of Pd, Xe, Ba, Nd, Sm, Gd, and Dy isotopes. This is done within the self-consistent Relativistic-Hartree-Bogoliubov (RHB) formalism, and supported by the Triaxial Projected Shell Model (TPSM) approach. Pairing interaction separable in the momentum space with DD-ME2 force parameter is used to generate the potential energy surfaces(PESs) under the axial and triaxial symmetry. Shape evolution manifest themself in very clear manner in almost all the isotopic chains. Properties of the global mimima have been found to be in good agreement with the available experimental data. Relatively flat PESs, and $γ$ -soft nature, have been suggested $^{108, 110}$ Pd, $^{132, 134}$ Xe and $^{134}$ Ba as good candidates for E(5) symmetry, while $^{102}$ Pd is not found suitable for E(5) symmetry. The PESs with a bump, and rigidity against triaxial variable( $γ$ ) suggested $^{150}$ Nd, $^{152}$ Sm and $^{154}$ Gd to be good candidates while $^{150}$ Sm and $^{156}$ Dy are poor candidates of X(5) critical-point symmetry. The findings of the present RHB calculations supported by TPSM are qualitatively in good agreement with the experimental and other theoretical calculations.
Comments:
accepted in Nucl. Phys. A
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.03686 [pdf]
NPA(2018)·24 citations
02
[Submitted on 11 Sept 2018]
Strangeness production via resonances in heavy-ion collisions at SIS energies
V. Steinberg🇩🇪 · J. Staudenmaier🇩🇪 · D. Oliinychenko🇩🇪 · F. Li🇩🇪 · Ö. Erkiner🇩🇪 · H. Elfner🇩🇪
Production of strange hadrons in elementary and heavy-ion reactions is studied with the hadronic transport approach SMASH (Simulating Many Accelerated Strongly-interacting Hadrons). The poorly known branching ratios of the relevant hadronic resonances are constrained from the known elementary hadronic cross sections and from invariant mass spectra of dileptons. The constrained model is employed as a baseline to compare to heavy-ion-collision experiments at low energies ( $E_{kin} = 1 - 2 A GeV$ ) and to predict some of the upcoming pion-beam results by HADES, which are expected to be sensitive to the resonance properties. The employed vacuum-resonance approach proves to be viable for small systems at these energies, but for large systems additional in-medium effects might be required.
Comments:
20 pages, 34 figures, 4 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.03828 [pdf]
PRC(2019)·32 citations
03
[Submitted on 11 Sept 2018]
Correlated structure of nuclear symmetry energy from covariant nucleon self-energy
Zhi Wei Liu🇨🇳 · Qian Zhao🇨🇳 · Bao Yuan Sun🇨🇳
Based on the Hugenholtz-Van Hove theorem, the symmetry energy $J$ and its density slope parameter $L$ are decomposed in terms of the nucleon self-energies within the covariant density functional (CDF) theory. It is found that two structural connections between the different ingredients of $J$ and $L$ construct the fundamental correlation between $L$ and $J$ in the relativistic covariant framework, while the additional contribution from the isovector scalar channel of nucleon-nucleon interaction and those from the second-order symmetry self-energies lead to a deviation, especially the latter limits severely its correlation coefficient and confidence level. In addition, the relationship between the Landau mass $M_{L}^{*}$ and the Dirac mass $M_{D}^{*}$ is approximated to a reliable linear correlation, which is demonstrate to be sensitive to the momentum dependence of the nucleon self-energies.
Comments:
10 pages, 5 figures, corresponding to the talk given in NuSYM2018
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.03837 [pdf]
4 citations
04
[Submitted on 8 Sept 2018]
Solution of the Specific Model of Five-Body Problem to Investigate the Effective Alpha-Nucleon Interaction in a Partial-wave Analysis
E. Ahmadi Pouya · A. A. Rajabi
In this paper, we have solved a simple specific model of the five-body problem in the framework of the Yakubovsky equations, restricted to the configurations of the alpha-nucleon types only, to investigate the effective interaction between an inert alpha-particle and a neutron. In general case, the Yakubovsky scheme for the solution of the five-body system leads to a set of four coupled equations related to four independent configurations, which can be restricted to two coupled ones, to describe the effective alpha-nucleon structure model, namely an inert four-body alpha-core and a nucleon. Hence, in such a model, the other configurations will not be taken into account. To calculate the binding energies of the five-body system in the model of alpha- nucleon structure, the two coupled equations are represented in the momentum space on the basis of the Jacobi momenta. After an explicit evaluation of the two coupled integral equations in a partial-wave analysis, the obtained equations are the starting point for a numerical calculation as an eigenvalue equation form, using typical iteration method. In the first step to the calculations, i.e. applying some spin-independent potential models, some obtained binding energy differences between the four-body as an alpha-particle and the five-body as an alpha-nucleon systems suggest that a simple effective interaction between an inert alpha-particle and a nucleon is attractive and of about 13 MeV. In addition, the represented binding energy results with respect to the regarded spin-independent potentials are in fair agreement with the obtained results from other methods.
Comments:
PACS. No: 21.45.+v, 21.30.Fe, 21.30.-x, 21.10.Dr http://www.actaphys.uj.edu.pl/findarticle?series=Reg&vol=48&page=1279. arXiv admin note: text overlap with arXiv:nucl-th/0605063, arXiv:1009.2319, arXiv:0704.2056 by other authors
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.03846 [pdf]
Acta Phys.Polon.B(2017)·1 citation
05
[Submitted on 11 Sept 2018]
Production of Light Nuclei at Thermal Freezeout in Heavy-Ion Collisions
Xinyuan Xu🇺🇸 · Ralf Rapp🇺🇸
We revisit the problem of the production of light atomic nuclei in ultrarelativistic heavy-ion collisions. While their production systematics is well produced by hadro-chemical freezeout at temperatures near the QCD pseudo-critical temperature, their small binding energies of a few MeV per nucleon suggest that they cannot survive as bound states under these conditions. Here, we adopt the concept of effective chemical potentials in the hadronic evolution from chemical to thermal freezeout (at typically $T_{fo}$ $≃$ 100\,MeV), which, despite frequent elastic rescatterings in hadronic matter, conserves the effective numbers of particles which are stable under strong interactions, most notably pions, kaons and nucleons. It turns out that the large chemical potentials that build up for antibaryons result in thermal abundances of light nuclei and antinuclei, formed at thermal freezeout, which essentially agree with the ones evaluated at chemical freezeout. Together with their transverse-momentum spectra, which also indicate a kinetic freezeout near $T_{fo}$ , this provides a natural explanation for their production systematics without postulating their survival at high temperatures.
Comments:
5 pages, 7 figures, v2: "Note added" corrected
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1809.04024 [pdf]
EPJA(2019)·34 citations
06
[Submitted on 11 Sept 2018]
Longitudinal Dynamics of High Baryon Density Matter in High Energy Heavy-Ion Collisions
Ming Li🇺🇸 · Chun Shen🇺🇸
In high energy heavy-ion collisions, the two colliding nuclei pass through each other leaving behind an almost baryon free central rapidity region. Most of the baryons are carried away by the nuclear remnants and are located in the so-called fragmentation regions. In previous papers \cite{Li:2016wzh,Li:2018ini}, it has been argued that very high baryon densities, more than ten times larger than the normal nuclear density, can be achieved in these fragmentation regions. In this paper, we assume the high baryon density matter is thermalized at the same time as the baryon-free quark-gluon plasma in the central rapidity region. We perform a 1+1D (temporal + longitudinal) hydrodynamic simulation covering both the fragmentation regions and the central rapidity region with the baryon diffusion equation included. Baryons are found to diffuse from the fragmentation regions to the central rapidity region driven by fugacity gradients. The baryon chemical potential at freezeout monotonically increases from the central rapidity region to the fragmentation regions, suggesting a rapidity scan in high energy heavy-ion collisions might be helpful in searching for the critical point of the QCD phase diagram.
Comments:
14 pages, 17 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1809.04034 [pdf]
PRC(2018)·33 citations
07
[Submitted on 8 Sept 2018] (cross-list from hep-ph)
Effect of an absorbing medium on particle oscillations
Valeriy Nazaruk🇷🇺
Particle oscillations in absorbing matter are considered. The approach based on the optical potential is shown to be inapplicable in the strong absorption region. Models with Hermitian Hamiltonian are analyzed. They give an increase of the process width in comparison with the model based on the optical potential.
Comments:
9 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1809.02841 [pdf]
PRC(2019)·1 citation
08
[Submitted on 10 Sept 2018] (cross-list from hep-ph)
Weak Neutral Current Axial Form Factor Using $(ν ˉ) ν$ -Nucleon Scattering and Lattice QCD Inputs
Raza Sabbir Sufian🇺🇸 · Keh-Fei Liu🇺🇸 · David G. Richards🇺🇸
We present a determination of the neutral current weak axial charge $G_{A}^{Z} (0) = - 0.654 (3)_{stat} (5)_{sys}$ using the strange quark axial charge $G_{A}^{s} (0)$ calculated with lattice QCD. We then perform a phenomenological analysis, where we combine the strange quark electromagnetic form factor from lattice QCD with (anti)neutrino-nucleon scattering differential cross section from MiniBooNE experiments in a momentum transfer region $0.24 ≲ Q^{2} ≲ 0.71$ GeV $^{2}$ to determine the neutral current weak axial form factor $G_{A}^{Z} (Q^{2})$ in the range of $0 ≲ Q^{2} \leq 1$ GeV $^{2}$ . This yields a phenomenological value of $G_{A}^{Z} (0) = - 0.687 (89)_{stat} (40)_{sys}$ . The value of $G_{A}^{Z} (0)$ constrained by the lattice QCD calculation of $G_{A}^{s} (0)$ , when compared to its phenomenological determination, provides a significant improvement in precision and accuracy and can be used to provide a constraint on the fit to $G_{A}^{Z} (Q^{2})$ for $Q^{2} > 0$ . This constrained fit leads to an unambiguous determination of (anti)neutrino-nucleon neutral current elastic scattering differential cross section near $Q^{2} = 0$ and can play an important role in numerically isolating nuclear effects in this region. We show a consistent description of $G_{A}^{Z} (Q^{2})$ obtained from the (anti)neutrino-nucleon scattering cross section data requires a nonzero contribution of the strange quark electromagnetic form factor. We demonstrate the robustness of our analysis by providing a post-diction of the BNL E734 experimental data.
Comments:
Published Version (20 pages, 4 figures)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1809.03509 [pdf]
JHEP(2020)·17 citations
09
[Submitted on 10 Sept 2018] (cross-list from hep-ph)
$J / ψ$ polarization in the CGC+NRQCD approach
Yan-Qing Ma🇨🇳 · Tomasz Stebel🇵🇱 · Raju Venugopalan🇺🇸
We compute the $J / ψ$ polarization observables $λ_{θ}$ , $λ_{ϕ}$ , $λ_{θ ϕ}$ in a Color Glass Condensate (CGC) + nonrelativistic QCQ (NRQCD) formalism that includes contributions from both color singlet and color octet intermediate states. Our results are compared to low $p_{T}$ data on $J / ψ$ polarization from the LHCb and ALICE experiments on proton-proton collisions at center-of-mass energies of $s = 7$ TeV and 8 TeV. Our CGC+NRQCD computation provides a better description of data for $p_{T} \leq 15$ GeV relative to extant next-to-leading (NLO) calculations within the collinear factorization framework. These results suggest that higher order computations in the CGC+NRQCD framework have the potential to greatly improve the accuracy of extracted values of the NRQCD universal long distance matrix elements.
Comments:
26 pages, 8 figures, accepted for publication in JHEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1809.03573 [pdf]
JHEP(2018)·47 citations
10
[Submitted on 11 Sept 2018] (cross-list from hep-ph)
Effect of Hagedorn States on Isothermal Compressibility of Hadronic Matter formed in Heavy-Ion Collisions: From NICA to LHC Energies
Arvind Khuntia🇮🇳 · Swatantra Kumar Tiwari🇮🇳 · Pramod Sharma🇮🇳 · Raghunath Sahoo🇮🇳 · Tapan Kumar Nayak🇮🇳
In this work, we have studied the isothermal compressibility ( $κ_{T}$ ) as a function of temperature, baryon chemical potential and centre-of-mass energy ( $s_{N N}$ ) using hadron resonance gas (HRG) and excluded-volume hadron resonance gas (EV-HRG) models. A mass cut-off dependence of isothermal compressibility has been studied for a physical resonance gas. Further, we study the effect of heavier resonances ( $>$ 2 GeV) on the isothermal compressibility by considering the Hagedorn mass spectrum, $ρ (m) \sim exp (bm) / (m^{2} + m_{0}^{2})^{5/4}$ . Here, the parameters, $b$ and $m_{0}$ are extracted after comparing the results of recent lattice QCD simulations at finite baryonic chemical potential. We find a significant difference between the results obtained in EV-HRG and HRG models at a higher temperatures and higher baryochemical potentials. The inclusion of the Hagedorn mass spectrum in the partition function for hadron gas has a large effect at a higher temperature. A higher mass cut-off in the Hagedorn mass spectrum takes the isothermal compressibility to a minimum value, which occurs near the Hagedorn temperature ( $T_{H}$ ). We show explicitly that at the future low energy accelerator facilities like FAIR (CBM), Darmstadt and NICA, Dubna the created matter would be incompressible compared to the high energy facilities like RHIC and LHC.
Comments:
Same as published paper
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1809.03780 [pdf]
PRC(2019)·20 citations
11
[Submitted on 11 Sept 2018] (cross-list from hep-ph)
Energy dependent kinetic freeze-out temperature and transverse flow velocity in high energy collisions
Li-Li Li🇨🇳 · Fu-Hu Liu🇨🇳
Transverse momentum spectra of negative and positive pions produced at mid-(pseudo)rapidity in inelastic or non-single-diffractive proton-proton collisions and in central nucleus-nucleus collisions over an energy range from a few GeV to above 10 TeV are analyzed by a (two-component) blast-wave model with Boltzmann-Gibbs statistics and with Tsallis statistics respectively. The model results are in similarly well agreement with the experimental data measured by a few productive collaborations who work at the Heavy Ion Synchrotron (SIS), Super Proton Synchrotron (SPS), Relativistic Heavy Ion Collider (RHIC), and Large Hadron Collider (LHC), respectively. The energy dependent kinetic freeze-out temperature and transverse flow velocity are obtained and analyzed. Both the quantities have quick increase from the SIS to SPS, and slight increase or approximate invariability from the top RHIC to LHC. Around the energy bridge from the SPS to RHIC, the considered quantities in proton-proton collisions obtained by the blast-wave model with Boltzmann-Gibbs statistics show more complex energy dependent behavior comparing with the results in other three cases.
Comments:
Updated version, 16 pages, 4 figures. Only the first component is used to extract $T_{0}$ and $β_{T}$ . Conclusions unchanged. arXiv admin note: text overlap with arXiv:1805.03342
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1809.03881 [pdf]
EPJA(2018)·27 citations
12
[Submitted on 11 Sept 2018] (cross-list from hep-ph)
Rho Meson spectral function in hot asymmetric nuclear matter
P.C. Raje Bhageerathi🇮🇳
The rho meson spectral function in hot and dense asymmetric nuclear matter (number densities of proton and neutron different) is evaluated in an effective chiral SU(3) model within the mean field approximation (MFA). The dependence of the vector meson masses on density and temperature, their variation with the asymmetry parameter, the form of the spectral function when the p <-> n symmetry is broken are studied. One can observe clear splitting of the longitudinal and the transverse modes among the rho isospin multiplets. The role of a running tensor coupling on the spectral function is also studied.
Comments:
25 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1809.04021 [pdf]
EPJA(2019)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE