Nuclear Theory·nucl-th

Tuesday·July 17, 2018

25 papers—18 primary·7 cross-listed

01
[Submitted on 12 Jul 2018]
Probing the transverse size of initial inhomogeneities with flow observables
Fernando G. Gardim🇧🇷 · Frédérique Grassi🇧🇷 · Pedro Ishida🇧🇷 · Matthew Luzum🇧🇷 · Pablo S. Magalhães🇧🇷 · Jacquelyn Noronha-Hostler🇺🇸
Disentangling the effect of initial conditions and medium properties is an open question in the field of relativistic heavy ion collisions. We argue that, while one can study the impact of initial inhomogeneities by varying their size, it is important to maintain the global properties fixed. We present a method to do this. We show that many observables are insensitive to the the hot spot sizes, including integrated vn, scaled distributions of vn, symmetric cumulants, eventplane correlations, and differential vn(pT ). We find however that the factorization breaking ratio rn and sub-leading component in a Principal Component Analysis are more sensitive to the initial granularity and can be used to probe short-scale features of the initial density.
Comments:
v2 significant text revision
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.05213 [pdf]
NPA(2019)·2 citations
02
[Submitted on 13 Jul 2018]
Microscopic collectivity: The ridge and strangeness enhancement from string-string interactions
Christian Bierlich🇸🇪
We present the microscopic model for collective effects, built on string-string interactions (string shoving and rope hadronization), recently implemented in the PYTHIA 8 and DIPSY event generators. Rope hadronization is shown to give a good description of strangeness enhancement across pp, pA and AA collisions systems, while string shoving qualitatively describes the ridge observed in pp collisions.
Comments:
4 pages, 2 figures. Proceedings for Quark Matter 2018. Version 2 updated with comments from referee
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1807.05271 [pdf]
NPA(2019)·27 citations
03
[Submitted on 14 Jul 2018]
Generalized Seniority Schmidt Model and the g-factors in Semi-magic Nuclei
Bhoomika Maheshwari🇲🇾 · Ashok Kumar Jain🇮🇳
We have recently applied the generalized seniority approach successfully to explain the B(E1)/B(E2)/B(E3) properties of the semi-magic nuclei. In the present paper, we extend this approach to the Schmidt model as Generalized Seniority Schmidt Model and calculate the g-factors of the various seniority states in the semi-magic nuclei. We find that the magnetic moments and the g-factors do show a particle number independent behavior in multi-j configurations, as expected in the seniority scheme. The calculated results explain the experimental trends quite well. We find that the g-factors of all the seniority states arising from a given multi-j configuration for identical nucleons is equal to the g-factor of the seniority $v = 1$ state from that configuration. Also, the g-factors are found to be a sensitive probe for fixing the multi-j configuration, which are fully consistent with the configurations assigned to explain the B(EL) properties in our previous works. We are also able to make definite predictions for many cases.
Comments:
Accepted in Nuclear Physics A. Key words: Sn-isotopes, Pb-isotopes, N = 82 isotones, Generalized Seniority, g-factor, Schmidt model, First excited $2^{+}$ states, Seniority isomers, Generalized Seniority Schmidt Model
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.05339 [pdf]
NPA(2019)·7 citations
04
[Submitted on 14 Jul 2018]
Estimating transport coefficients of interacting pion gas with K-matrix cross sections
Guruprasad Kadam🇮🇳 · Swapnali Pawar🇮🇳 · Hiranmaya Mishra🇮🇳
We estimate the transport coefficients, $v i z .$ , shear and bulk viscosities as well as thermal and electrical conductivities, of hot pionic matter using relativistic Boltzmann equation in relaxation time approximation. We use K-matrix parametrization of pion-pion cross sections to estimate the transport coefficients which incorporate multiple heavy resonances while simultaneously preserving the unitarity of S-matrix. We compare transport coefficients estimated using K-matrix parametrization with existing literature on pionic transport coefficients. We find that the K-matrix scheme estimations are in reasonable agreement with previous results.
Comments:
Revised version, Accepted for publication in Journal Of Physics G
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.05370 [pdf]
J.Phys.G(2019)·11 citations
05
[Submitted on 14 Jul 2018]
New measures of longitudinal decorrelation of harmonic flow
Piotr Bozek🇵🇱 · Wojciech Broniowski🇵🇱
Harmonic flow in relativistic heavy-ion collisions is observed in a broad range of rapidities, and the flow at different rapidities is correlated. However, fluctuations lead to a small decorrelation of the harmonic flow magnitudes and flow angles at different rapidities. Using a hydrodynamic model with Glauber Monte Carlo initial conditions we show that the flow angle decorrelation strongly depends on the flow magnitude in the event. We propose observables to measure this effect in experiment.
Comments:
talk given at XXVIIth International Conference on Ultrarelativistic Nucleus-Nucleus Collision Quark Matter 2018
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.05391 [pdf]
NPA(2019)·1 citation
06
[Submitted on 14 Jul 2018]
IP-Glasma Phenomenology Beyond 2D
Scott McDonald🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
We present a novel formulation of the IP-Glasma initial state model in 3+1D in which the 2+1D boost invariant IP-Glasma is generalized through JIMWLK rapidity evolution of the pre-collision Wilson lines \cite{Schenke:2016ksl}. In order to consistently accommodate a non-boost-invariant system, the initial conditions are generalized to 3+1D. By breaking boost invariance, the 3+1D model no longer trivially satisfies Gauss' law at the initial time, and we now enforce it locally. We compare the time evolution of the chromo-electric and chromo-magnetic fields as well as the transverse and longitudinal pressures in the 3+1D case with the boost invariant result.
Comments:
To be submitted to the conference proceedings for the XXVIIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2018), held May 13-19, 2018 in Venice, Italy
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.05409 [pdf]
NPA(2019)·16 citations
07
[Submitted on 14 Jul 2018]
Hydrodynamic Fluctuations in Relativistic Heavy-Ion Collisions
Mayank Singh🇨🇦 · Chun Shen🇺🇸 · Scott McDonald🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
We present a novel approach to the treatment of thermal fluctuations in the (3+1)-D viscous hydrodynamic simulation MUSIC. The phenomenological impact of thermal fluctuations on hadronic observables is investigated using the IP-Glasma + hydrodynamics + hadronic cascade hybrid approach. The anisotropic flow observed in heavy-ion collision experiments is mostly attributed to the hydrodynamic response to the event-by-event collision geometry and to the sub-nucleon quantum fluctuations. However, hydrodynamic fluctuations are present during the dynamical evolution of the Quark Gluon Plasma (QGP) and are quantified by the fluctuation-dissipation theorem. They can leave their imprint on final-state observables. By analyzing the thermal noise mode-by-mode, we provide a consistent scheme of treating these fluctuations as the source terms for hydrodynamic fields. These source terms are then evolved together with hydrodynamic equations of motion. Such a treatment captures the non-perturbative nature of the evolution for these thermal fluctuations.
Comments:
Proceedings for Quark Matter 2018
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.05451 [pdf]
NPA(2019)·59 citations
08
[Submitted on 14 Jul 2018]
Thermalization & hydrodynamics in Bjorken & Gubser flows
Chandrodoy Chattopadhyay🇮🇳 · Ulrich Heinz🇺🇸 · Subrata Pal🇮🇳 · Gojko Vujanovic🇺🇸
The dynamical scaling behavior of hydrodynamic and non-hydrodynamic moments of the distribution function is studied using third-order Chapman-Enskog hydrodynamics and anisotropic hydrodynamics for systems undergoing Bjorken and Gubser expansions, where exact solutions of the Boltzmann equation in Relaxation Time Approximation (RTA) are available for comparison. While dimensionless quantities like normalized shear, pressure anisotropy and normalized entropy show at late times universal scaling relations with small (large) Knudsen number for Bjorken (Gubser) flows, dimensionful quantities like the entropy per unit rapidity do not. Although the two hydrodynamic approximation schemes describe the exact attractors for normalized shear with high accuracy, their description for the normalized entropy is less precise. We attribute this to non-negligible couplings to non-hydrodynamic modes in the entropy evolution.
Comments:
4 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.05462 [pdf]
NPA(2019)·4 citations
09
[Submitted on 15 Jul 2018]
High precision nuclear mass predictions towards a hundred kilo-electron-volt accuracy
Zhongming Niu🇨🇳 · Haozhao Liang🇯🇵 · Baohua Sun🇨🇳 · Yifei Niu🇷🇴 · Jianyou Guo🇨🇳 · Jie Meng🇨🇳
Mass is a fundamental property and an important fingerprint of atomic nucleus. It provides an extremely useful test ground for nuclear models and is crucial to understand energy generation in stars as well as the heavy elements synthesized in stellar explosions. Nuclear physicists have been attempting at developing a precise, reliable, and predictive nuclear model that is suitable for the whole nuclear chart, while this still remains a great challenge even in recent days. Here we employ the Fourier spectral analysis to examine the deviations of nuclear mass predictions to the experimental data and to present a novel way for accurate nuclear mass predictions. In this analysis, we map the mass deviations from the space of nucleon number to its conjugate space of frequency, and are able to pin down the main contributions to the model deficiencies. By using the radial basis function approach we can further isolate and quantify the sources. Taking a pedagogical mass model as an example, we examine explicitly the correlation between nuclear effective interactions and the distributions of mass deviations in the frequency domain. The method presented in this work, therefore, opens up a new way for improving the nuclear mass predictions towards a hundred kilo-electron-volt accuracy, which is argued to be the chaos-related limit for the nuclear mass predictions.
Comments:
8 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1807.05535 [pdf]
Sci.Bull.(2018)·45 citations
10
[Submitted on 15 Jul 2018]
Analytical solutions of causal relativistic hydrodynamic equations for Bjorken and Gubser flows
Chandrodoy Chattopadhyay🇮🇳 · Amaresh Jaiswal🇮🇳 · Sunil Jaiswal🇮🇳 · Subrata Pal🇮🇳
We obtain general analytical solutions of third-order viscous hydrodynamic equations for Bjorken and Gubser flows in systems with vanishing bulk viscosity and chemical potential, and having a constant shear relaxation time. We also analytically characterize and determine the hydrodynamic attractors for such systems by studying the universal behavior of these solutions at both early and late times. Finally we study the properties of these hydrodynamic attractors for transport coefficients obtained from relativistic kinetic theory in the relaxation-time approximation.
Comments:
4 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.05544 [pdf]
NPA(2019)·7 citations
11
[Submitted on 15 Jul 2018]
Confronting hydrodynamic predictions with Xe-Xe data
Giuliano Giacalone🇫🇷 · Jacquelyn Noronha-Hostler🇺🇸 · Matthew Luzum🇧🇷 · Jean-Yves Ollitrault🇫🇷
Comparing collision systems of different size, at near the same collision energy, offers us the opportunity to probe the scaling behavior and therefore the nature of the system itself. Recently, we made predictions for Xe-Xe collisions at 5.44 TeV using viscous hydrodynamic simulations, noting that the scaling from the larger Pb-Pb system is rather generic, and arguing that robust predictions can be made that do not depend on details of the model. Here we confront our predictions with measurements that were subsequently made in a short Xe-Xe run at the LHC by the ALICE, ATLAS, and CMS collaborations. We find that the predictions are largely confirmed. Of particular interest is a strong indication of a non-spherical shape for the $^{129}$ Xe nucleus.
Comments:
Proceedings for Quark Matter 2018, 4 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1807.05557 [pdf]
NPA(2019)·8 citations
12
[Submitted on 15 Jul 2018]
Initial conditions for nuclear collisions: theory overview
Aleksas Mazeliauskas🇩🇪
We overview the current status and recent developments on initial conditions in ultra-relativistic nucleus-nucleus collisions. Specifically, we look at the progress in understanding the role of sub-nucleonic fluctuations in large and small collision systems. Next, we review the current ideas of going beyond boost invariant initial conditions and introducing physically motivated rapidity fluctuations at RHIC and LHC energies. Finally, we discuss the time evolution of initial stages and the matching between different descriptions of the QGP.
Comments:
8 pages, 4 figures, Proceedings of the XXVIIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2018); version 2: updated references and Fig 2(a)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1807.05586 [pdf]
NPA(2019)·6 citations
13
[Submitted on 15 Jul 2018]
Hadronic observables in p+p and d+Au collisions at RHIC using CGC+PYTHIA
Björn Schenke🇺🇸 · Sören Schlichting🇺🇸 · Prithwish Tribedy🇺🇸 · Raju Venugopalan🇺🇸
The IP-Glasma model of CGC combined with the Lund model of PYTHIA provides a very successful description of hadron production from gluon dominated non-equilibrium matter in various small collision systems. This new CGC+PYTHIA framework, naturally reproduces several characteristic features of the hadronic observables such as the mass ordering of $v_{2} (p_{T})$ and $⟨ p_{T} ⟩$ , often ascribed to collectivity driven by hydrodynamics at the LHC. In this contribution we extend our work to provide a systematic comparison of particle spectra and multiplicity distributions in p+p and d+Au collisions at the RHIC.
Comments:
4 pages, 3 figures, proceedings of Quark Matter 2018
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.05632 [pdf]
NPA(2019)·3 citations
14
[Submitted on 16 Jul 2018]
Nucleus-nucleus potential from identical-particle interference
Ning Wang🇨🇳 · Yongxu Yang🇨🇳 · Min Liu🇨🇳 · Chengjian Lin🇨🇳
Based on the quantum interference between two-identical-nucleus scattering at energies around the Coulomb barrier, the barrier positions for $^{58}$ Ni+ $^{58}$ Ni and $^{16}$ O+ $^{16}$ O are extracted from Mott oscillations in the angular distributions around 90 $^{\circ}$ for the first time. The angle separation of pairs of Mott scattering valleys around 90 $^{\circ}$ has a direct relationship with the closest distance between two nuclei in elastic scattering. Together with the barrier height from fusion excitation function, the extracted barrier position provides a sensitive probe to constrain the model predictions for the nucleus-nucleus potential barrier.
Comments:
4 figures, accepted for publication in Phys. Lett. B
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex); Quantum Physics (quant-ph)
arXiv:
1807.05646 [pdf]
PLB(2018)·1 citation
15
[Submitted on 16 Jul 2018]
One-body Langevin dynamics in heavy-ion collisions at intermediate energies
Hao Lin🇺🇸 · Pawel Danielewicz🇺🇸
We present a new framework to treat the dissipation and fluctuation dynamics associated with nucleon-nucleon scattering in heavy-ion collisions. The two-body collision processes are effectively described in terms of the diffusion of nucleons in viscous nuclear media, governed by a set of Langevin equations in momentum space. The new framework combined with the usual mean field dynamics can be used to simulate heavy-ion collisions at intermediate energies. As a proof of principle, we simulate Au + Au reactions and obtain results consistent with other existing codes under the same constrained conditions. We also study the formation of fragments in Sn + Sn reactions at 50 MeV/nucleon, and results are discussed and compared with two other models commonly employed for collisions.
Comments:
11 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.05673 [pdf]
PRC(2019)·20 citations
16
[Submitted on 16 Jul 2018]
Applications of deep learning to relativistic hydrodynamics
Hengfeng Huang🇨🇳 · Bowen Xiao🇨🇳 · Huixin Xiong🇨🇳 · Zeming Wu🇨🇳 · Yadong Mu🇨🇳 · Huichao Song (Peking U)🇨🇳
In this proceeding, we will briefly review our recent progress on implementing deep learning to relativistic hydrodynamics. We will demonstrate that a successfully designed and trained deep neural network, called {\tt stacked U-net}, can capture the main features of the non-linear evolution of hydrodynamics, which could also rapidly predict the final profiles for various testing initial conditions.
Comments:
QM2018 proceeding, 4 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); cond-mat.dis-nn (cond-mat.dis-nn); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1807.05728 [pdf]
NPA(2019)·5 citations
17
[Submitted on 16 Jul 2018]
Astrophysical S-factor for the deep sub-barrier fusion reactions of light nuclei
Vinay Singh🇮🇳 · Debasis Atta🇮🇳 · Md. A. Khan🇮🇳 · D. N. Basu🇮🇳
The cross sections for the deep sub-barrier fusion reaction of light nuclei are calculated within the theoretical framework of the selective resonant tunneling model. In this model, assumption of a complex square-well nuclear potential is invoked to describe the absorption inside the nuclear well. The theoretical estimates for these cross sections agree well with the experimentally measured values. The features of the astrophysical S-factor are derived in terms of this model. Present formalism appears to be particularly useful for the low energy resonant reactions between two charged nuclei.
Comments:
5 pages including 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.05815 [pdf]
NPA(2019)·10 citations
18
[Submitted on 13 Jul 2018]
Beam energy dependence of the relativistic retardation effects of electrical fields on the $π^{-} / π^{+}$ ratio in heavy-ion collisions
Gao-Feng Wei · Gao-Chan Yong · Li Ou · Qi-Jun Zhi · Zheng-Wen Long
In this article we investigate the beam energy dependence of relativistic retardation effects of electrical fields on the single and double $π^{-} / π^{+}$ ratios in three heavy-ion reactions with an isospin- and momentum-dependent transport model IBUU11. With the beam energy increasing from 200 to 400 MeV/nucleon, effects of the relativistically retarded electrical fields on the $π^{-} / π^{+}$ ratio are found to increase gradually from negligibly to considerably significant as expectedly; it is however, the interesting observation is the relativistic retardation effects of electrical fields on the $π^{-} / π^{+}$ ratio are becoming gradually insignificant as the beam energy further increasing from 400 to 800 MeV/nucleon. Moreover, we also investigate the isospin dependence of relativistic retardation effects of electrical fields on the $π^{-} / π^{+}$ ratio in two isobar reaction systems of $^{96}$ Ru+ $^{96}$ Ru and $^{96}$ Zr+ $^{96}$ Zr at the beam energies from 200 to 800 MeV/nucleon. It is shown that the relativistic retardation effects of electrical fields on the $π^{-} / π^{+}$ ratio are independent of the isospin of reaction. Furthermore, we also examine the double $π^{-} / π^{+}$ ratio in reactions of $^{96}$ Zr+ $^{96}$ Zr over $^{96}$ Ru+ $^{96}$ Ru at the beam energies from 200 to 800 MeV/nucleon with the static field and retarded field, respectively. It is shown the double $π^{-} / π^{+}$ ratio from two reactions is still an effective observable of symmetry energy without the interference of electrical field due to using the relativistic calculation compared to the nonrelativistic calculation.
Comments:
8 pages, 7 figures. Abbreviated abstract to meet the criterion of arXiv platform. Accepted for publication in Physical Review C. An extended but necessary complementary study to arXiv:1709.09127
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1807.05878 [pdf]
PRC(2018)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE