Nuclear Theory·nucl-th

Monday·November 7, 2016

9 papers—5 primary·4 cross-listed

01
The rapidity and thermal motion induced transverse momentum distributions of identified charged particles produced in Au-Au collisions at RHIC energies
Zhi-Jin Jiang🇨🇳 · Jia-Qi Hui🇨🇳 · Yu Zhang🇨🇳
It is widely believed that the quark-gluon plasma (QGP) might be formed in the current heavy ion collisions. It is also widely recognized that the relativistic hydrodynamics is one of the best tools for describing the process of expansion and particlization of QGP. In this paper, by taking into account the effects of thermal motion, a hydrodynamic model including phase transition from QGP state to hadronic state is used to analyze the rapidity and transverse momentum distributions of identified charged particles produced in heavy ion collisions. A comparison is made between the theoretical results and experimental data. The theoretical model gives a good description to the corresponding measurements made in Au-Au collisions at RHIC energies.
nucl-thAdv.High Energy Phys.(2017)·2 citations
02
Radiative capture reaction for $^{17}$ Ne formation within a full three-body model
J. Casal · E. Garrido · R. de Diego · J. M. Arias · M. Rodríguez-Gallardo
Background: The breakout from the hot Carbon-Nitrogen-Oxigen (CNO) cycles can trigger the rp-process in type I x-ray bursts. In this environment, a competition between $^{15} O (α, γ)^{19} Ne$ and the two-proton capture reaction $^{15} O (2 p, γ)^{17} Ne$ is expected. Purpose: Determine the three-body radiative capture reaction rate for $^{17} Ne$ formation including sequential and direct, resonant and non-resonant contributions on an equal footing. Method: Two different discretization methods have been applied to generate $^{17}$ Ne states in a full three-body model: the analytical transformed harmonic oscillator method and the hyperspherical adiabatic expansion method. The binary $p$ -- $^{15}$ O interaction has been adjusted to reproduce the known spectrum of the unbound $^{16}$ F nucleus. The dominant $E 1$ contributions to the $^{15} O (2 p, γ)^{17} Ne$ reaction rate have been calculated from the inverse photodissociation process. Results: Three-body calculations provide a reliable description of $^{17}$ Ne states. The agreement with the available experimental data on $^{17}$ Ne is discussed. It is shown that the $^{15} O (2 p, γ)^{17} Ne$ reaction rates computed within the two methods agree in a broad range of temperatures. The present calculations are compared with a previous theoretical estimation of the reaction rate. Conclusions: It is found that the full three-body model provides a reaction rate several orders of magnitude larger than the only previous estimation. The implications for the rp-process in type I x-ray bursts should be investigated.
nucl-thPRC(2016)·19 citations
03
Symmetry-unrestricted Skyrme mean-field study of heavy nuclei
W. Ryssens · P.-H. Heenen · M. Bender
In the light of recent experimental developments, increasing attention is devoted to nuclear phenomena related to rotational excitations of exotic intrinsic nuclear configurations that often lack symmetries present in the majority of nuclei. Examples include configurations with a non-vanishing octupole moment. In order to describe this kind of states, we have developed a new computer code to solve the self-consistent mean-field equations, able to use most of today's effective Skyrme interactions and working in coordinate-space. We report on the development of MOCCa, a code based on the same principles as EV8, but offering the user individual control on many symmetry assumptions. In addition, the HF+BCS pairing treatment of EV8 has been generalised to the full machinery of Hartree-Fock-Bogoliubov transformations. We discuss as example the static fission barrier of $^{226}$ Ra, prefacing extended studies in the region, using the recent series of Skyrme parameterizations SLy5s1 through SLy5s8.
nucl-thPoS(2016)·1 citation
04
Hadron yields, the chemical freeze-out and the QCD phase diagram
A. Andronic🇩🇪 · P. Braun-Munzinger🇩🇪 · K. Redlich🇵🇱 · J. Stachel🇩🇪
We present the status of the chemical freeze-out, determined from fits of hadron yields with the statistical hadronization (thermal) model, with focus on the data at the LHC. A description of the yields of hadrons containing light quarks as well as the application of the model for the production of the J/ $ψ$ meson is presented. The implications for the QCD phase diagram are discussed.
nucl-thnucl-exJ.Phys.Conf.Ser.(2017)·68 citations
05
Mirror and triplet displacement energies within nuclear DFT: numerical stability
Pawel Baczyk · Jacek Dobaczewski · Maciej Konieczka · Takashi Nakatsukasa · Koichi Sato · Wojciech Satula
Isospin-symmetry-violating class II and III contact terms are introduced into the Skyrme energy density functional to account for charge dependence of the strong nuclear interaction. The two new coupling constants are adjusted to available experimental data on triplet and mirror displacement energies, respectively. We present preliminary results of the fit, focusing on its numerical stability with respect to the basis size.
nucl-thActa Phys.Polon.B(2017)·1 citation
06
Heavy meson spectroscopy under strong magnetic field
Tetsuya Yoshida🇯🇵 · Kei Suzuki🇰🇷
Spectra of the neutral heavy mesons, $η_{c} (1 S, 2 S)$ , $J / ψ$ , $ψ (2 S)$ , $η_{b} (1 S, 2 S, 3 S)$ , $Υ (1 S, 2 S, 3 S)$ , $D$ , $D^{*}$ , $B$ , $B^{*}$ , $B_{s}$ and $B_{s}^{*}$ , in a homogeneous magnetic field are analyzed in a potential model of constituent quarks. To obtain anisotropic wave functions and the corresponding eigenvalues, the cylindrical Gaussian expansion method is applied, where the wave functions for transverse and longitudinal directions in the cylindrical coordinate are expanded by the Gaussian bases separately. Energy level structures in the wide range of magnetic fields are obtained and the deformation of the wave functions is shown, which reflects effects of the spin mixing, the Zeeman splitting and quark Landau levels. The contribution from the magnetic catalysis in heavy-light mesons is discussed as a change of the light constituent quark mass.
↳ hep-phhep-latnucl-thPRD(2016)·67 citations
07
Role of $σ$ exchange in the $γ p \to ϕp$ process and scaling with the $f_{1}$ axial vector meson from a Reggeized model
Byung-Geel Yu🇰🇷 · Hungchong Kim🇰🇷 · Kook-Jin Kong🇰🇷
We investigate the role driven by the scalar meson $σ$ exchange in the photoproduction of the vector meson $ϕ$ (1020) off a proton by using a Reggeized model. Based on the $π^{0} (135) + σ (500) + f_{2} (1270)$ +Pomeron exchanges, we demonstrate that the $σ$ exchange plays the role to reproduce the bump structure at the forward angle in the differential cross section as well as the peaking behavior in the total cross section observed in the CLAS Collaboration. We also discuss the possible observation of the scaled cross section $s^{7} d σ / d t$ at the production angle $θ = 9 0^{\circ}$ from the CLAS data. It is found that the axial vector meson $f_{1} (1285)$ exchange with the trajectory $α_{f_{1}} (t) = 0.028 t + 0.9 \pm 0.2$ arising from the axial anomaly of the QCD vacuum plays the role to clarify the scaling up to 5 GeV.
↳ hep-phnucl-thPRD(2017)·14 citations
08
Neutron star properties and the equation of state for its core
J. L. Zdunik · M. Fortin · P. Haensel
Few unified equations of state for neutron star matter where core and crust are described using the same nuclear model are available. However the use of non-unified equations of state with a simplified matching between the crust and the core has been shown to introduce uncertainties in the radius determination which can be larger than the expected precision of the next generation of X-ray satellites. We aim at eliminating the dependence of the radius and mass of neutron staron the detailed model for the crust and on the crust-core matching procedure. We solve the approximate equations of the hydrostatic equilibrium for the crust of neutron stars obtaining a precise formula for the radius which depends only on the core mass and radius, and on the baryon chemical potential at the core-crust interface and on the crust surface. For a fully accreted crust one needs additionally the value of the total deep crustal heating per one accreted nucleon. For typical neutron star masses the approximate approach allows to determine the neutron star radius with an error ~0.1% (~ 10 m, equivalent to a 1% inaccuracy in the crust thickness). The formalism applies to neutron stars with a catalyzed or a fully accreted crust. The difference in the neutron star radius between the two models is proportional to the total energy release due to deep crustal heating. For a given model of dense matter describing the neutron star core, the radius of a neutron star can be accurately determined independently of the crust model with a precision much better than the ~5% one expected from the next generation of X-ray satellites. This allows to circumvent the problem of the radius uncertainty which may arise when non-unified equations of state for the crust and the core are used.
↳ astro-ph.HEastro-ph.SRnucl-thAstron.Astrophys.(2017)·50 citations
09
Quark mass effects in quark number susceptibilities
Thorben Graf🇫🇷 · Peter Petreczky🇺🇸
The quark degrees of freedom of the QGP with special focus on mass effects are investigated. A next-to-leading-order perturbation theory approach with quark mass dependence is applied and compared to lattice QCD results.
↳ hep-phhep-latnucl-thJ.Phys.Conf.Ser.(2017)·3 citations

Affiliations

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