Nuclear Theory·nucl-th

Tuesday·July 10, 2018

17 papers—9 primary·8 cross-listed

01
Mean field and beyond description of nuclear structure with the Gogny force: A review
L. M. Robledo🇪🇸 · T. R. Rodríguez🇪🇸 · R. R. Rodríguez-Guzmán🇰🇼
Nowadays, the Gogny force is a referent in the theoretical description of nuclear structure phenomena. Its phenomenological character manifests in a simple analytical form that allows for implementations of techniques both at the mean field and beyond all over the nuclide chart. Over the years, multiple applications of the standard many-body techniques in an assorted set of nuclear structure applications have produced results which are in a rather good agreement with experimental data. The agreement allows for a simple interpretation of those intriguing phenomena in simple terms and gives confidence on the predictability of the interaction. The present status on the implementation of different many body techniques with the Gogny force is reviewed with a special emphasis on symmetry restoration and large amplitude collective motion.
nucl-thnucl-exJ.Phys.G(2019)·217 citations
02
The Elasticity of Nuclear Pasta
M. E. Caplan · A. S. Schneider · C. J. Horowitz
The elastic properties of neutron star crusts are relevant for a variety of currently observable or near-future electromagnetic and gravitational wave phenomena. These phenomena may depend on the elastic properties of nuclear pasta found in the inner crust. We present large scale classical molecular dynamics simulations where we deform nuclear pasta. We simulate idealized samples of nuclear pasta and describe their breaking mechanism. We also deform nuclear pasta that is arranged into many domains, similar to what is known for the ions in neutron star crusts. Our results show that nuclear pasta may be the strongest known material, perhaps with a shear modulus of $1 0^{30} ergs/cm^{3}$ and breaking strain greater than 0.1.
nucl-thPRL(2018)·82 citations
03
Density Functional Theory (DFT) for atomic nuclei: a simple introduction
G. Colò🇮🇹
The present contribution does not aim at replacing the huge and often excellent literature on DFT for atomic nuclei, but tries to provide an updated introduction to this topic. The goal would be, ideally, to help a fresh M.Sc. or Ph.D. student (or a researcher from other fields) to become acquainted with some basic concepts, and then move to the specialized textbooks or papers with some ability for orienteering. We first introduce the basics of DFT, and show the difference with the "naive" mean-field theory, that is doomed to fail as a model even in the simple case of uniform nuclear matter. We introduce the Energy Density Functionals (EDFs) that are used in nuclear structure, with few examples of their applications. The concepts of symmetry breaking and restoration are briefly discussed. We also include an introduction to the time-dependent extension of DFT that, so far, has been implemented essentially only in the adiabatic approximation and has been applied mainly to the study of nuclear vibrations. With this material, we hope that any reader is able to deal with the texts that go deeper into each of the topics, having understood that DFT is probably the best compromise in nuclear structure theory between simplicity, accuracy, and broad range of applicability.
nucl-thcond-mat.othernucl-ex1 citation
04
Going from Asymmetric Nuclei to Neutron Stars to Tidal Polarizability in Gravitational Waves
Mannque Rho🇫🇷 · Yong-Liang Ma🇨🇳
Among the five-year government-funded World Class University Projects in Korea, the category-3 program approved at Hanyang University in Seoul led to an exploratory effort to go from neutron-rich nuclei to dense matter in neutron stars. The principal results in what transpired in the effort -- and what followed afterwards -- are described with the focus on the possibly important, hitherto unexplored, role played in nuclear dynamics of topology and hidden symmetries of QCD. The potential link to the proton mass problem is pointed out.
nucl-thastro-ph.SRhep-phIJMPE(2018)·3 citations
05
The role of angle dependent phase rotations of reaction amplitudes in $η$ photoproduction on protons
A. Švarc · H. Osmanović · M. Hadžimehmedović · R. Omerović · J. Stahov · V. Kashevarov · K. Nikonov · M. Ostrick · L. Tiator
It has recently been proven that the invariance of observables with respect to angle dependent phase rotations of reaction amplitudes mixes multipoles changing also their relative strength [1]. All contemporary partial wave analyses (PWA) in $η$ photoproduction on protons, either energy dependent (ED) [2-5] or single energy (SE) [6] do not take this effect into consideration. It is commonly accepted that there exist quite some similarity in the $E 0 +$ multipole for all PWA, but notable differences in this, but also in remaining partial waves still remain. In this paper we demonstrate that once this phase rotations are properly taken into account, all contemporary ED and SE partial wave analysis become almost identical for the dominant $E 0 +$ multipole, and the agreement among all other multipoles becomes much better. We also show that the the measured observables are almost equally well reproduced for all PWA, and the remaining differences among multipoles can be attributed solely to the difference of predictions for unmeasured observables. So, new measurements are needed.
nucl-thnucl-exPRC(2018)·4 citations
06
Spectra and flow of light nuclei in relativistic heavy ion collisions at RHIC and the LHC
Wenbin Zhao🇨🇳 · Lilin Zhu🇨🇳 · Hua Zheng🇨🇳 · Che Ming Ko🇺🇸 · Huichao Song🇨🇳
Within the framework of the coalescence model based on the phase-space distributions of protons and neutrons generated from the {{\tt iEBE-VISHNU}} hybrid model with {{\tt AMPT}} initial conditions, we study the spectra and elliptic flow of deuterons and helium-3 in relativistic heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Larger Hadron Collider (LHC). Results from our model calculations for Au + Au collisions at $s_{N N} = 200$ GeV at RHIC and Pb+Pb collisions at $s_{N N} = 2.76$ TeV at the LHC are compared with available experimental data. Good agreements are generally seen between theoretical results and experimental data, except that the calculated yield of helium-3 in Pb + Pb collisions at $s_{N N} = 2.76$ TeV underestimates the data by about a factor of two. Possible reasons for these discrepancies are discussed. We also make predictions on the spectra and elliptic flow of deuterons and helium-3 in Pb + Pb collisions at $s_{N N} = 5.02$ TeV that are being studied at LHC.
nucl-thPRC(2018)·78 citations
07
Few- and many-nucleon systems with semilocal coordinate-space regularized chiral two- and three-body forces
E. Epelbaum🇩🇪 · J. Golak🇵🇱 · K. Hebeler🇩🇪 · T. Hüther🇩🇪 · H. Kamada🇯🇵 · H. Krebs🇩🇪 · P. Maris🇺🇸 · U.-G. Meißner🇩🇪 · A. Nogga🇩🇪 · R. Roth🇩🇪 · R. Skibiński🇵🇱 · K. Topolnicki🇵🇱 and 3 other authors
We present a complete calculation of nucleon-deuteron scattering as well as ground and low-lying excited states of light nuclei in the mass range A=3-16 up through next-to-next-to-leading order in chiral effective field theory using semilocal coordinate-space regularized two- and three-nucleon forces. It is shown that both of the low-energy constants entering the three-nucleon force at this order can be reliably determined from the triton binding energy and the differential cross section minimum in elastic nucleon-deuteron scattering. The inclusion of the three-nucleon force is found to improve the agreement with the data for most of the considered observables.
nucl-thnucl-exPRC(2019)·113 citations
08
Incorporating Brueckner-Hartree-Fock correlations in the Density Matrix Expansion approach
Y.N. Zhang🇺🇸 · S.K. Bogner🇺🇸 · R.J. Furnstahl🇺🇸
Recently, a microscopically motivated nuclear energy density functional was derived by applying the density matrix expansion to the Hartree-Fock (HF) energy obtained from long-range chiral effective field theory two- and three-nucleon interactions. However, the HF approach cannot account for all many-body correlations. One class of correlations is included by Brueckner-Hartree-Fock (BHF) theory, which gives an improved definition of the one-body HF potential by replacing the interaction by a reaction matrix $G$ . In this paper, we find that the difference between the $G$ -matrix and the nucleon-nucleon potential $V_{NN}$ can be well accounted for by a truncated series of contact terms. This is consistent with renormalization group decoupling generating a series of counterterms as short-distance physics is integrated out. The coefficients $C_{n}$ of the power series expansion $\sum C_{n} q^{n}$ for the counterterms are examined for two potentials at different renormalization group resolutions and at a range of densities. The success of this expansion for $G - V_{NN}$ means we can apply the density matrix expansion at the HF level with low-momentum interactions and density-dependent zero-range interactions to model BHF correlations.
nucl-thPRC(2018)·13 citations
09
A mixing interpolation method to mimic pasta phases in compact star matter
David Blaschke🇷🇺 · David Alvarez-Castillo🇷🇺
We present a new method to interpolate between two matter phases that allows for a description of mixed phases and can be used, e.g., for mimicking transitions between pasta structures occuring in the crust as well as in the inner core of compact stars. This interpolation method is based on assuming switch functions that are used to define a mixture of subphases while fulfilling constraints of thermodynamic stability. The width of the transition depends on a free parameter, the pressure increment relative to the critical pressure of a Maxwell construction. As an example we present a trigonometric function ansatz for the switch function together with a pressure increment during the transition. We note that the resulting mixed phase equation of state bears similarities with the appearance of substitutional compounds in neutron star crusts and with the sequence of transitions between different pasta phases in the hadron-to-quark matter transition. We apply this method to the case of a hadron-to-quark matter transition and test the robustness of the compact star mass twin phenomenon against the appearance of pasta phases modeled in this way.
nucl-thastro-ph.HEhep-phEPJA(2020)·15 citations
10
Model-Independent Bounds on $R (J / ψ)$
Thomas D. Cohen🇺🇸 · Henry Lamm🇺🇸 · Richard F. Lebed🇺🇸
We present a model-independent bound on $R (J / ψ) \equiv B R (B_{c}^{+} \to J / ψ τ^{+} ν_{τ}) / B R (B_{c}^{+} \to J / ψ μ^{+} ν_{μ})$ . This bound is constructed by constraining the form factors through a combination of dispersive relations, heavy-quark relations at zero-recoil, and the limited existing determinations from lattice QCD. The resulting 95\% confidence-level bound, $0.20 \leq R (J / ψ) \leq 0.39$ , agrees with the recent LHCb result at $1.3 σ$ , and rules out some previously suggested model form factors.
↳ hep-phhep-exhep-latnucl-thJHEP(2018)·48 citations
11
Causality and dissipation in relativistic polarizeable fluids
David Montenegro🇧🇷 · Giorgio Torrieri🇧🇷
We analyze the breakdown of causality for the perfect fluid limit in a medium with polarizeability. We show that to restore causality a relaxation term linking vorticity and polarization, analogous to the Israel-Stewart term linking viscous forces and gradients,is required. This term provides a minimum amount of dissipation a locally thermalized relativistic medium with polarizeability must have, independently of its underlying degrees of freedom. For ferromagnetic materials an infrared acausal mode remains, which we interpret as a Banks-Casher mode signaling spontaneous magnetization. With these ingredients, we propose a candidate for a fully causal Lagrangian of a relativistic polarizeable system near the perfect fluid limit.
↳ hep-thhep-phnucl-thPRD(2019)·102 citations
12
Asymptotic behavior of Nambu-Bethe-Salpeter wave functions for scalar systems with a bound state
Shinya Gongyo🇯🇵 · Sinya Aoki🇯🇵
We study the asymptotic behaviors of the Nambu-Bethe-Salpeter (NBS) wave functions, which are important for the HAL QCD potential method to extract hadron interactions, in the case that a bound state exists in the system. We consider the complex scalar particles, two of which lead to the formation of a bound state. In the case of the two-body system, we show that the NBS wave functions for the bound state as well as scattering states in the asymptotic region behave like the wave functions in quantum mechanics, which carry the information of the binding energy as well as the scattering phase shift. This analysis theoretically establishes under some conditions that the HAL QCD potential can correctly reproduce not only the scattering phase shift but also the binding energy. As an extension of the analysis, we also study the asymptotic behaviors of all possible NBS wave functions in the case of the three-body systems, two of which can form a bound states.
↳ hep-lathep-phnucl-thPTEP(2018)·7 citations
13
Heavy-flavor flow-harmonics in high-energy nuclear collisions: time-development and eccentricity fluctuations
A. Beraudo🇮🇹 · A. De Pace🇮🇹 · M. Monteno🇮🇹 · M. Nardi🇮🇹 · F. Prino🇮🇹
We study the development of heavy-flavor flow harmonics in high-energy nuclear collisions. The elliptic and triangular flow of heavy-flavor hadrons, arising from the finite impact parameter of the two nuclei and from event-by-event fluctuations of the initial geometry, is analyzed in detail, considering the contribution from particles decoupling from the fireball at various times. We also study the dependence of the flow harmonics on the event-shape fluctuations, considering events belonging to the same centrality class but characterized by very different eccentricities (or vice-versa).
↳ hep-phnucl-exnucl-thNPA(2019)·5 citations
14
On strangeness in NA61/SHINE
Maciej P. Lewicki (for the NA61/SHINE Collaboration)🇵🇱
NA61/SHINE is a fixed target experiment at the CERN Super-Proton- Synchrotron. The main goals of the experiment are to discover the critical point of strongly interacting matter and to study the properties of the onset of deconfinement. In order to reach these goals, a study of hadron production properties is performed in nucleus-nucleus, proton-proton and proton-nucleus interactions as a function of collision energy and size of the colliding nuclei. In this paper, I will review recent results on strangeness production in p+p, Be+Be and Ar+Sc collisions in the SPS energy range. Kinematic spectra and mean multiplicities of kaons obtained with various analysis methods will be shown. An overview of strangeness production and its dependence on system size in the vicinity of the phase transition will be presented as well.
↳ hep-exhep-phnucl-exnucl-thActa Phys.Polon.Supp.(2018)·1 citation
15
Phenomenological bound on the viscosity of the hadron resonance gas
Snigdha Ghosh🇮🇳 · Sabyasachi Ghosh🇮🇳 · Sumana Bhattacharyya🇮🇳
We have explored some phenomenological issues during calculations of transport coefficients for hadronic matter, produced in the experiments of heavy ion collisions. Here, we have used an ideal hadron resonance gas model to demonstrate the issues. On the basis of dissipation mechanism, the hadronic zoo is classified into resonance and non-resonance members, who participate in dissipation via strong decay and scattering channels respectively. Imposing our phenomenological restriction, we are able to provide a rough upper and lower bound estimations of transport coefficients. Interestingly, we find that our proposed lower limit estimation for shear viscosity to entropy density ratio is little larger than its quantum lower bound. By taking a simple example, we have demonstrated how our proposed restriction help to tune any estimation of transport coefficients within its numerical band, proposed by us.
↳ hep-phnucl-thPRC(2018)·17 citations
16
Hidden strange pentaquark in constituent quark models
Xuejie Liu🇨🇳 · Hongxia Huang🇨🇳 · Jialun Ping🇨🇳
In the framework of the chiral quark model, we investigate the hidden strange pentaquark system of the $N ϕ$ state with the quantum numbers of IJ= $\frac{1}{2}$ $\frac{3}{2}$ . The results show that the $N ϕ$ state can be bound through the interaction of the $σ$ meson exchange plus the effect of the channel coupling, which means that the effect of the channel coupling has an influence on the existence of this bound state.
↳ hep-phnucl-thPRC(2018)·11 citations
17
Super-Knee Cosmic Rays from Galactic Neutron Star Merger Remnants
Shigeo S. Kimura🇺🇸 · Kohta Murase🇺🇸 · Peter Mészáros🇺🇸
The detection of gravitational waves and electromagnetic counterparts from a binary neutron star (BNS) merger confirmed that it is accompanied by the launch of fast merger ejecta. Analogous to supernova remnants, forward shocks formed by the interaction of the ejecta with interstellar material will produce high-energy cosmic rays. We investigate the possibility that Galactic neutron star merger remnants (NSMRs) significantly contribute to the observed cosmic rays in the energy range between the knee and the ankle. Using typical parameters obtained by modeling of GW170817, we find that NSMRs can accelerate iron nuclei up to $\sim 500$ PeV. We calculate the cosmic-ray spectrum and composition observed on Earth, and show that the Galactic NSMR scenario can account for the experimental cosmic-ray data in the 20 -- 1000 PeV range. Our model can naturally explain the hardening feature around 20 PeV for total cosmic-ray spectrum, which has been observed by the Telescope Array Low Energy extension and the IceTop air shower array.
↳ astro-ph.HEhep-phnucl-thApJ(2018)·34 citations

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first authorsco-authorsvia INSPIRE