Nuclear Theory·nucl-th

Monday·December 19, 2016

19 papers—13 primary·6 cross-listed

01
[Submitted on 15 Dec 2016]
Event-By-Event Initial Conditions for Heavy Ion Collisions
Steven Rose🇺🇸 · Rainer J. Fries🇺🇸
The early time dynamics of heavy ion collisions can be described by classical fields in an approximation of Quantum ChromoDynamics (QCD) called Color Glass Condensate (CGC). Monte-Carlo sampling of the color charge for the incoming nuclei are used to calculate their classical gluon fields. Following the recent work by Chen et al. we calculate the energy momentum tensor of those fields at early times in the collision event-by-event. This can then be used for subsequent hydrodynamic evolution of the single events.
Comments:
Proceedings for Hot Quarks 2016; 4 pages; 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1612.05271 [pdf]
J.Phys.Conf.Ser.(2017)·1 citation
02
[Submitted on 16 Dec 2016]
Solution of the Skyrme-Hartree-Fock-Bogolyubov equations in the Cartesian deformed harmonic-oscillator basis. (VIII) hfodd (v2.73y): a new version of the program
N. Schunck🇺🇸 · J. Dobaczewski🇬🇧 · W. Satuła🇵🇱 · P. Bączyk🇵🇱 · J. Dudek🇫🇷 · Y. Gao🇫🇮 · M. Konieczka🇵🇱 · K. Sato🇯🇵 · Y. Shi🇫🇮 · X.B. Wang🇫🇮 · T.R. Werner🇵🇱
We describe the new version (v2.73y) of the code HFODD which solves the nuclear Skyrme Hartree-Fock or Skyrme Hartree-Fock-Bogolyubov problem by using the Cartesian deformed harmonic-oscillator basis. In the new version, we have implemented the following new features: (i) full proton-neutron mixing in the particle-hole channel for Skyrme functionals, (ii) the Gogny force in both particle-hole and particle-particle channels, (iii) linear multi-constraint method at finite temperature, (iv) fission toolkit including the constraint on the number of particles in the neck between two fragments, calculation of the interaction energy between fragments, and calculation of the nuclear and Coulomb energy of each fragment, (v) the new version 200d of the code HFBTHO, together with an enhanced interface between HFBTHO and HFODD, (vi) parallel capabilities, significantly extended by adding several restart options for large-scale jobs, (vii) the Lipkin translational energy correction method with pairing, (viii) higher-order Lipkin particle-number corrections, (ix) interface to a program plotting single-particle energies or Routhians, (x) strong-force isospin-symmetry-breaking terms, and (xi) the Augmented Lagrangian Method for calculations with 3D constraints on angular momentum and isospin. Finally, an important bug related to the calculation of the entropy at finite temperature and several other little significant errors of the previous published version were corrected.
Comments:
52 pages; 6 figures, 3 tables; submitted for publication in Computer Physics Communications
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1612.05314 [pdf]
Comput.Phys.Commun.(2017)·77 citations
03
[Submitted on 16 Dec 2016]
From local correlations to regional systematics
Z. Z. Q · M. Bao · Y. Lei
Local correlations of $2_{1}^{+}$ excitation energies and B(E2, $2_{1}^{+} \to g.s.$ ) values require linear $N_{p} N_{n}$ systematics in a logarithmic scale, as confirmed by an experiment survey. Based on local correlations of $α$ -decay energies, neutron separation energies, and proton separation energies, one can decouple them into their proton and neutron contributions separately. These contributions exhibit smooth regional systematics beyond the $N_{p} N_{n}$ scheme.
Comments:
6 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1612.05333 [pdf]
PRC(2017)·1 citation
04
[Submitted on 16 Dec 2016]
Simultaneous microscopic description of nuclear level density and radiative strength function
N. Quang Hung · N. Dinh Dang · L. T. Quynh Huong
Nuclear level density (NLD) and radiative strength function (RSF) are described simultaneously within a microscopic approach, which takes into account the thermal effects of the exact pairing as well as the giant resonances within the phonon-damping model. The good agreement between the results of calculations and experimental data extracted by the Oslo group for $^{170, 171, 172}$ Yb isotopes shows the importance of exact thermal pairing in the description of NLD at low and intermediate excitation energies and invalidates the assumption based on the Brink-Axel hypothesis in the description of the RSF.
Comments:
5 pages, 2 figures, some typos are corrected, accepted for publication in Phys. Rev. Lett
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1612.05391 [pdf]
PRL(2017)·56 citations
05
[Submitted on 16 Dec 2016]
First estimation of the fission dynamics of the spectator created in heavy-ion collisions
K. Mazurek🇵🇱 · A. Szczurek🇵🇱 · P.N. Nadtochy🇷🇺
In peripheral high-energy heavy-ion collisions only parts of colliding nuclei interact leading to the production of a fireball. The remnants of such nuclei are called spectators. We estimated the excitation energy as a function of impact parameter. Their excitation energy is of the order of 100 MeV. The dynamical evolution of hot nuclei is described by solving a set of Langevin equations in four-dimensional collective coordinate space. The range of nuclear masses and excitation energies suits very well to ability of our model. Thus for the first time we investigate dynamically the fission and evaporation channels in de-excitation of the spectators produced in heavy-ions collision.
Comments:
8 pages,3 figures, Presented at the XXIII Nuclear Physics Workshop "Marie and Pierre Curie" Kazimierz Dolny, 27th September - 2nd October 2016, Poland
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1612.05397 [pdf]
Acta Phys.Polon.Supp.(2017)·1 citation
06
[Submitted on 16 Dec 2016]
Determination of S-factors with the LIT method
Winfried Leidemann · Sergio Deflorian · Victor D. Efros
The precise determination of astrophysical S-factors is essential for a detailed understanding of the nucleosynthesis in its various facets. It is discussed how the Lorentz integral transform (LIT) method can be applied for such a determination. The astrophysical S-factor for the proton-deuteron radiative capture is considered as test case. The importance of a specific many-body basis used for the LIT equation solution is pointed out. The excellent results of the test are discussed.
Comments:
7 pages, 2 figures, conference EFB23
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1612.05401 [pdf]
Few Body Syst.(2017)·1 citation
07
[Submitted on 16 Dec 2016]
Nuclear matter properties with nucleon-nucleon forces up to fifth order in the chiral expansion
Jinniu Hu🇨🇳 · Ying Zhang🇨🇳 · Evgeny Epelbaum🇩🇪 · Ulf-G. Meißner🇩🇪 · Jie Meng🇨🇳
The properties of nuclear matter are studied using state-of-the-art nucleon-nucleon forces up to fifth order in chiral effective field theory. The equations of state of symmetric nuclear matter and pure neutron matter are calculated in the framework of the Brueckner-Hartree-Fock theory. We discuss in detail the convergence pattern of the chiral expansion and the regulator dependence of the calculated equations of state and provide an estimation of the truncation uncertainty. For all employed values of the regulator, the fifth-order chiral two-nucleon potential is found to generate nuclear saturation properties similar to the available phenomenological high precision potentials. We also extract the symmetry energy of nuclear matter, which is shown to be quite robust with respect to the chiral order and the value of the regulator.
Comments:
10 pages, 3 figures, 3 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1612.05433 [pdf]
PRC(2017)·48 citations
08
[Submitted on 16 Dec 2016]
Effect of the Coulomb interaction on the liquid-gas phase transition of nuclear matter
Rana Nandi · Stefan Schramm
We investigate the role of the Coulomb interaction on the liquid-gas phase transition of nuclear matter with three different values of proton fraction ( $Y_{p}$ =0.5,0.3 and 0.1), relevant for heavy-ion physics as well as various astrophysical scenarios, within the framework of quantum molecular dynamics. We perform simulations for a wide range of density and temperature with and without the Coulomb interaction and calculate the two-point correlation functions of nucleon density fluctuations for all the configurations to determine the phase transition region. We also determine the critical end point of the liquid-gas phase transition for all three values of proton fraction considered. We observe that the Coulomb interaction reduces the transition temperature by about 2 MeV for nuclear matter with $Y_{p}$ =0.5 and 0.3 and by about 1 MeV for nuclear matter with $Y_{p}$ =0.1. However, the critical density is found to be more or less insensitive to the Coulomb interaction.
Comments:
17 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1612.05448 [pdf]
PRC(2017)·8 citations
09
[Submitted on 16 Dec 2016]
Electromagnetic radiation and collectivity in small quark-gluon droplets
Chun Shen🇺🇸 · Jean-Francois Paquet🇺🇸 · Gabriel S. Denicol🇧🇷 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
We study the multiplicity and rapidity dependence of thermal and prompt photon production in p+Pb collisions at 5.02 TeV, using a (3+1)D viscous hydrodynamic framework. Direct photon anisotropic flow coefficients $v_{2, 3}^{γ}$ and nuclear modification factor $R_{pPb}^{γ} (p_{T})$ are presented in both the p-going (backward) and the Pb-going (forward) directions. The interplay between initial state cold nuclear effect and final state thermal enhancement at different rapidity regions is discussed. The proposed rapidity dependent thermal photon enhancement and direct photon anisotropic flow observables can elucidate non-trivial longitudinal dynamics of hot quark-gluon plasma droplets created in small collision systems.
Comments:
4 pages, 3 figures, proceeding for Hard Probes 2016, parallel talk presented by C. Shen
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1612.05464 [pdf]
Nucl.Part.Phys.Proc.(2017)·5 citations
10
[Submitted on 15 Dec 2016]
Electroweak single-pion production off the nucleon: from threshold to high invariant masses
R. González-Jiménez🇧🇪 · N. Jachowicz🇧🇪 · K. Niewczas🇧🇪 · J. Nys🇧🇪 · V. Pandey🇺🇸 · T. Van Cuyck🇧🇪 · N. Van Dessel🇧🇪
[Background] Neutrino-induced single-pion production (SPP) provides an important contribution to neutrino-nucleus interactions, ranging from intermediate to high energies. There exists a good number of low-energy models in the literature to describe the neutrinoproduction of pions in the region around the Delta resonance. Those models consider only lowest-order interaction terms and, therefore, fail in the high-energy region (pion-nucleon invariant masses, $W$ >2 GeV). [Purpose] Our goal is to develop a model for electroweak SPP off the nucleon, which is applicable to the entire energy range of interest for present and future neutrino-oscillation experiments. [Method] We start with the low-energy model of [Phys.Rev.D76,033005(2007)], which includes resonant contributions and background terms derived from the pion-nucleon Lagrangian of chiral-perturbation theory. Then, from the background contributions, we build a high-energy model using a Regge approach. The low- and high-energy models are combined, in a phenomenological way, into a hybrid model. [Results] The Hybrid model is identical to the low-energy model in the low-W region, but, for W>2 GeV, it implements the desired high-energy behavior dictated by Regge theory. We have tested the high-energy model by comparing with one-pion production data from electron and neutrino reactions. The Hybrid model is compared with electron-proton scattering data, with neutrino SPP data and with the predictions of the NuWro Monte Carlo event generator. [Conclusions] Our model is able to provide satisfactory predictions of the electroweak one-pion production cross section from pion threshold to high $W$ . Further investigation and more data are needed to better understand the mechanisms playing a role in the electroweak SPP process in the high-W region, in particular, those involving the axial current contributions.
Comments:
30 pages, 21 figures. Includes comparison with NuWro predictions. New references added
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1612.05511 [pdf]
PRD(2017)·52 citations
11
[Submitted on 15 Dec 2016]
Bulk viscous corrections to photon production in the quark-gluon plasma
Sigtryggur Hauksson🇨🇦 · Chun Shen🇺🇸 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
Photons radiated in heavy-ion collisions are a penetrating probe, and as such can play an important role in the determination of the quark-gluon plasma (QGP) transport coefficients. In this work we calculate the bulk viscous correction to photon production in two-to-two scattering reactions. Phase-space integrals describing the bulk viscous correction are evaluated explicitly in order to avoid the forward scattering approximation which is shown to be poor for photons at lower energies. We furthermore present hydrodynamical simulations of AA collisions focusing on the effect of this calculation on photonic observables. Bulk corrections are shown to reduce the elliptic flow of photons at higher $p_{T}$ .
Comments:
5 pages, 7 figures, based on talk at Hard Probes 2016
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1612.05517 [pdf]
Nucl.Part.Phys.Proc.(2017)·7 citations
12
[Submitted on 16 Dec 2016]
Collective excitations of a quantized vortex in $^{3} P_{2}$ superfluids in neutron stars
Chandrasekhar Chatterjee · Mareike Haberichter · Muneto Nitta
We discuss collective excitations (both fundamental and solitonic excitations) of quantized superfluid vortices in neutron $^{3} P_{2}$ superfluids, which likely exist in high density neutron matter such as neutron stars. Besides the well-known Kelvin modes (translational zero modes), we find a gapfull mode whose low-energy description takes the simple form of a double sine-Gordon model. The associated kink solution and its effects on spontaneous magnetization inside the vortex core are analyzed in detail.
Comments:
12 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1612.05588 [pdf]
PRC(2017)·20 citations
13
[Submitted on 16 Dec 2016]
A Blast Wave Model With Viscous Corrections
Zhidong Yang🇺🇸 · Rainer J. Fries🇺🇸
Hadronic observables in the final stage of heavy ion collision can be described well by fluid dynamics or blast wave parameterizations. We improve existing blast wave models by adding shear viscous corrections to the particle distributions in the Navier-Stokes approximation. The specific shear viscosity $η / s$ of a hadron gas at the freeze-out temperature is a new parameter in this model. We extract the blast wave parameters with viscous corrections from experimental data which leads to constraints on the specific shear viscosity at kinetic freeze-out. Preliminary results show $η / s$ is rather small.
Comments:
Proceedings for HQ 2016,4 pages,3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1612.05629 [pdf]
J.Phys.Conf.Ser.(2017)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE