Nuclear Theory·nucl-th

Tuesday·July 21, 2020

22 papers—12 primary·10 cross-listed

01
Entanglement Rearrangement in Self-Consistent Nuclear Structure Calculations
Caroline Robin🇺🇸 · Martin J. Savage🇺🇸 · Nathalie Pillet🇫🇷
Entanglement properties of $^{4}$ He and $^{6}$ He are investigated using nuclear many-body calculations, specifically the single-nucleon entanglement entropy, and the two-nucleon mutual information and negativity. Nuclear wavefunctions are obtained by performing active-space no-core configuration-interaction calculations using a two-body nucleon-nucleon interaction derived from chiral effective field theory. Entanglement measures within single-particle bases, the harmonic oscillator (HO), Hartree-Fock (HF), natural (NAT) and variational natural (VNAT) bases, are found to exhibit different degrees of complexity. Entanglement in both nuclei is found to be more localized within NAT and VNAT bases than within a HO basis for the optimal HO parameters, and, as anticipated, a core-valence (tensor product) structure emerges from the full six-body calculation of $^{6}$ He. The two-nucleon mutual information shows that the VNAT basis, which typically exhibits good convergence properties, effectively decouples the active and inactive spaces. We conclude that measures of one- and two-nucleon entanglement are useful in analyzing the structure of nuclear wave functions, in particular the efficacy of basis states, and may provide useful metrics toward developing more efficient schemes for ab initio computations of the structure and reactions of nuclei, and quantum many-body systems more generally.
nucl-thquant-phPRC(2021)·119 citations
02
Probing in-medium nucleon-nucleon inelastic scattering cross section by using energetic n/p ratio
Zong-Zhen Zhang🇨🇳 · Ya-Fei Guo🇨🇳 · Gao-Chan Yong🇨🇳
Based on the Isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, the in-medium nucleon-nucleon inelastic scattering ( which is dominated by pion production at low and intermediate energies) is explored. It is found that the in-medium modification of nucleon-nucleon inelastic scatterings appears to reduce the neutron to proton ratio n/p at higher kinetic energies. Although the in-medium modification of nucleon-nucleon inelastic scatterings, as expected, affects the value of $π^{-} / π^{+}$ ratio, considering a series of undetermined properties of delta resonance and $π$ in medium, the energetic neutron to proton ratio n/p is more suitable to be used to probe the in-medium correction of nucleon-nucleon inelastic scatterings.
nucl-thnucl-exPRC(2021)·4 citations
03
An efficient solution for Dirac equation in 3D lattice space with the conjugate gradient method
B. Li · Z. X. Ren · P. W. Zhao
An efficient method, preconditioned conjugate gradient method with a filtering function (PCG-F), is proposed for solving iteratively the Dirac equation in 3D lattice space for nuclear systems. The filtering function is adopted to avoid the variational collapsed problem and a momentum-dependent preconditioner is introduced to promote the efficiency of the iteration. The PCG-F method is demonstrated in solving the Dirac equation with given spherical and deformed Woods-Saxon potentials. The solutions given by the inverse Hamiltonian method in 3D lattice space and the shooting method in radial coordinate space are reproduced with a high accuracy. In comparison with the existing inverse Hamiltonian method, the present PCG-F method is much faster in the convergence of the iteration, in particular for deformed potentials. It may also provide a promising way to solve the relativistic Hartree-Bogoliubov equation iteratively in the future.
nucl-thnucl-exPRC(2020)·23 citations
04
Thermal photons as a sensitive probe of $α$ -cluster in C+Au collisions at the BNL Relativistic Heavy Ion Collider
Pingal Dasgupta🇨🇳 · Guo-Liang Ma🇨🇳 · Rupa Chatterjee🇮🇳 · Li Yan🇨🇳 · Song Zhang🇨🇳 · Yu-Gang Ma🇨🇳
Different orientations of $α$ -clustered carbon nuclei colliding with heavy ions can result in a large variation in the value of anisotropic flow. Thus, photon flow observables from clustered $^{12} C$ and $^{197} Au$ collisions could be a potential probe to study the `direct photon puzzle'. We calculate the transverse momentum spectra and anisotropic flow coefficients ( $v_{n}$ ) of thermal photons from collisions of triangular $α$ -clustered carbon and gold at $s_{NN} = 200$ GeV at RHIC using a hydrodynamic model framework and compare the results with those obtained from unclustered carbon and gold collisions. The slope of the thermal photon spectra is found to vary moderately for different orientations of collisions. However, we find that the elliptic ( $v_{2}$ ) and triangular flow ( $v_{3}$ ) coefficients of direct photons for specific configurations are significantly larger and predominantly formed by the QGP radiation. A strong anti-correlation between initial spatial ellipticity and triangularity is observed in an event-by-event framework of $α$ -clustered $C + Au$ collisions. These special features provide us an opportunity to detect the exotic nature of cluster structure inside carbon nucleus using the photon probe in the future experiments.
nucl-thhep-phnucl-exEPJA(2021)·20 citations
05
Probing high-density symmetry energy using heavy-ion collisions at intermediate energies
Gao-Chan Yong🇨🇳 · Ya-Fei Guo🇨🇳
The nuclear symmetry energy, which describes the energy difference of per proton and neutron in nuclear matter, has been extensively studied within the last two decades. Around saturation density, both the value and the slope of the nuclear symmetry energy have been roughly constrained, its high-density behavior is now still in argument. Probing high-density symmetry energy at terrestrial laboratories is being carried out at facilities that offer radioactive beams worldwide. While relevant experiments are being conducted, we theoretically developed more advanced isospin-dependent transport model including new physics such as nucleon-nucleon short-range correlations and in-medium isospin-dependence of baryon-baryon scattering cross section. New sensitive probes of high-density symmetry energy are provided, such as squeezed-out neutron to proton ratio, photon and light cluster as well as the production of mesons with strangeness or hidden strangeness. The blind spots of probing the high-density symmetry energy by sensitive observable are demonstrated. Model dependence of frequently used sensitive probes of the symmetry energy has been studied thoroughly based on different transport models. A qualitative observable of neutron to proton ratio at high emitting energy is proposed to probe the high-density symmetry energy qualitatively. The probed density regions of the symmetry energy are carefully studied. Effects of nucleon-nucleon short-range correlations on the some sensitive observables of the symmetry energy in heavy-ion collisions are explored carefully. Probing the curvature of the symmetry energy by involving the slope information of the symmetry energy at saturation point in the transport model is proposed.
nucl-thnucl-exNucl.Phys.Rev.(2020)·11 citations
06
Towards the continuum coupling in nuclear lattice effective field theory I: A three-particle model
J.-J. Wu🇨🇳 · Ulf-G. Meißner🇩🇪
Weakly bound states often occur in nuclear physics. To precisely understand their properties, the coupling to the continuum should be worked out explicitely. In a first step, we use a simple nuclear model in the continuum and on a lattice to investigate the influence of a third particle on a loosely bound state of a particle and a heavy core.
nucl-thhep-lathep-phCPC(2020)·1 citation
07
Lifetime of the hypertriton
F. Hildenbrand🇩🇪 · H.-W. Hammer🇩🇪
We calculate the lifetime of the hypertriton as function of the $Λ$ separation energy $B_{Λ}$ in an effective field theory with $Λ$ and deuteron degrees of freedom. We also consider the impact of new measurements of the weak decay parameter of the $Λ$ . While the sensitivity of the total width to $B_{Λ}$ is small, the partial widths for decays into individual final states and the experimentally measured ratio $R = Γ_{^{3} He} / (Γ_{^{3} He} + Γ_{p d})$ show a strong dependence. For the standard value $B_{Λ} = (0.13 \pm 0.05)$ MeV, we find $R = 0.37 \pm 0.05$ , which is in good agreement with past experimental studies and theoretical calculations. For the recent STAR value $B_{Λ} = (0.41 \pm 0.12 \pm 0.11)$ MeV, we obtain $R = 0.57 \pm 0.11$ .
nucl-thhep-phPRC(2020)·35 citations
08
Coulomb Corrections for Bose-Einstein Correlations from One- And Three-Dimensional Lévy-Type Source Functions
Bálint Kurgyis🇭🇺 · Dániel Kincses🇭🇺 · Márton Nagy🇭🇺 · Máté Csanád🇭🇺
In the study of femtoscopic correlations in high-energy physics, besides Bose--Einstein correlations, one has to take final-state interactions into account. Amongst them, Coulomb interactions play a prominent role in the case of charged particles. Recent measurements have shown that in heavy-ion collisions, Bose--Einstein correlations can be best described by Lévy-type sources instead of the more common Gaussian assumption. Furthermore, three-dimensional measurements have indicated that, depending on the choice of frame, a deviation from spherical symmetry observed under the assumption of Gaussian source functions persists in the case of Lévy-type sources. To clarify such three-dimensional Lévy-type correlation measurements, it is thus important to study the effect of Coulomb interactions in the case of non-spherical Lévy sources. We calculated the Coulomb correction factor numerically in the case of such a source function for assorted kinematic domains and parameter values using the Metropolis--Hastings algorithm and compared our results with previous methods to treat Coulomb interactions in the presence of Lévy sources.
nucl-thhep-phUniverse(2023)·22 citations
09
Near-threshold $K^{*} (892)^{+}$ meson production in the interaction of $π^{-}$ mesons with nuclei
E. Ya. Paryev🇷🇺
We study the inclusive strange vector meson $K^{*} (892)^{+}$ production in $π^{-} A$ reactions at near-threshold laboratory incident pion momenta of 1.4--2.0 GeV/c within a nuclear spectral function approach. The approach accounts for incoherent primary $π^{-}$ meson--proton $π^{-} p \to K^{*} (892)^{+} Σ^{-}$ production processes as well as the influence of the scalar $K^{*} (892)^{+}$ --nucleus potential (or the $K^{*} (892)^{+}$ in-medium mass shift) on these processes. We calculate the absolute differential and total cross sections for the production of $K^{*} (892)^{+}$ mesons off carbon and tungsten nuclei at laboratory angles of 0 $^{\circ}$ --45 $^{\circ}$ and at these momenta within five scenarios for the above shift. We show that the $K^{*} (892)^{+}$ momentum distributions and their excitation functions (absolute and relative) possess a high sensitivity to changes in the in-medium $K^{*} (892)^{+}$ mass shift in the low-momentum region of 0.1--0.6 GeV/c. Therefore, the measurement of such observables in a dedicated experiment at the GSI pion beam facility in the near-threshold momentum domain will allow to get valuable information on the $K^{*} (892)^{+}$ in-medium properties.
nucl-thhep-phnucl-exCPC(2020)·6 citations
10
Structure of Quark Star: A Comparative Analysis of Bayesian Inference and Neural Network Based Modeling
Silvia Traversi🇮🇹 · Prasanta Char🇮🇹
In this work, we compare two powerful parameter estimation methods namely Bayesian inference and Neural Network based learning to study the quark matter equation of state with constant speed of sound parametrization and the structure of the quark stars within the two-family scenario. We use the mass and radius estimations from several X-ray sources and also the mass and tidal deformability measurements from gravitational wave events to constrain the parameters of our model. The results found from the two methods are consistent. The predicted speed of sound is compatible with the conformal limit.
nucl-thastro-ph.HEApJ(2020)·27 citations
11
Comment on "Comparison of optical potential for nucleons and $Δ$ resonances" by Arie Bodek and Tejin Cai
U. Mosel🇩🇪
In \cite{Bodek:2020wbk} Bodek and Cai have tried to extract the potentials for nucleons and $Δ$ resonances from electron-nucleus inclusive scattering data. They find that the $Δ$ potential is considerably more attractive than that of the nucleons. This result is at variance with the results of a multitude of analyses of (e,A) and ( $γ A$ ) interactions, performed about 35 years ago.
nucl-thhep-exnucl-ex4 citations
12
Nature of the $Λ nn$ $(J^{π} = 1/ 2^{+}, I = 1)$ and $_{Λ}^{3} H^{*} (J^{π} = 3/ 2^{+}, I = 0)$ states
M. Schäfer🇨🇿 · B. Bazak🇮🇱 · N. Barnea🇮🇱 · J. Mareš🇨🇿
The nature of the $Λ nn$ and $_{Λ}^{3} H^{*} (J^{π} = 3/ 2^{+}, I = 0)$ states is investigated within a pionless effective field theory at leading order, constrained by the low energy $Λ N$ scattering data and hypernuclear 3- and 4-body data. Bound state solutions are obtained using the stochastic variational method, the continuum region is studied by employing two independent methods - the inverse analytic continuation in the coupling constant method and the complex scaling method. Our calculations yield both the $Λ nn$ and $_{Λ}^{3} H^{*}$ states unbound. We conclude that the excited state $_{Λ}^{3} H^{*}$ is a virtual state and the $Λ nn$ pole located close to the three-body threshold in a complex energy plane could convert to a true resonance with Re $(E) > 0$ for some considered $Λ N$ interactions. Finally, the stability of resonance solutions is discussed and limits of the accuracy of performed calculations are assessed.
nucl-thnucl-exPRC(2021)·18 citations
13
Fluctuating Relativistic hydrodynamics from Crooks theorem
Giorgio Torrieri🇧🇷
We use the Crooks fluctuation theorem together with Zubarev hydrodynamics to develop a bottom-up theory of hydrodynamic fluctuations. We also use thermodynamic uncertainity relations to estimate bottom-up limits to dissipative transport coefficients.
↳ hep-thhep-lathep-phnucl-th+1JHEP(2021)·22 citations
14
Confronting GW190814 with hyperonization in dense matter and hypernuclear compact stars
Armen Sedrakian🇩🇪 · Fridolin Weber🇺🇸 · Jia-Jie Li🇩🇪
We examine the possibility that the light companion in the highly asymmetric binary compact object coalescence event GW190814 is a hypernuclear star. We use density functional theory with functionals that have been tuned to the properties of $Λ$ hypernuclei as well as astrophysical constraints placed by the masses of the most massive millisecond pulsars, the mass-radius range inferred from the NICER experiment, and the binary neutron star merger event GW170817. We compute general-relativistic static and maximally rotating Keplerian configurations of purely nucleonic and hypernuclear stars. We find that while nucleonic stars are broadly consistent with a neutron star being involved in GW190814, this would imply no new degrees of freedom in the dense matter up to 6.5 times the nuclear saturation density. Allowing for hyperonization of dense matter, we find that the maximal masses of hypernuclear stars, even for maximal rapidly rotating configurations, are inconsistent with a stellar nature interpretation of the light companion in GW190814, implying that this event involved two black holes rather than a neutron star and a black hole.
↳ astro-ph.HEnucl-thPRD(2020)·79 citations
15
Updated analysis of jet quenching at RHIC and LHC within the light cone path integral approach
B.G. Zakharov🇷🇺
We present results of a detailed analysis of experimental data on the nuclear modification factor $R_{AA}$ and the flow coefficient $v_{2}$ for light hadrons from RHIC for $0.2$ TeV Au+Au collisions and from LHC for $2.76$ and $5.02$ TeV Pb+Pb, and $5.44$ TeV Xe+Xe collisions. We perform calculations within the light-cone path integral approach to induced gluon emission. We use running $α_{s}$ which is frozen at low momenta at some value $α_{s}^{f r}$ . We find that the RHIC data support somewhat larger value of $α_{s}^{f r}$ . For the $χ^{2}$ optimized values of $α_{s}^{f r}$ , the theoretical predictions are in reasonable agreement with data on $R_{AA}$ and $v_{2}$ . Calculations made for different formation times and life-times of the QGP show that jet quenching at the RHIC and LHC energies is only weakly sensitive to the initial and final stages of the QCD matter evolution.
↳ hep-phnucl-thJ.Phys.G(2021)·11 citations
16
Complexified quasinormal modes and the pole-skipping in a holographic system at finite chemical potential
Navid Abbasi🇨🇳 · Sara Tahery🇨🇳
We develop a method to study coupled dynamics of gauge-invariant variables, constructed out of metric and gauge field fluctuations on the background of a AdS $_{5}$ Reissner-Nordström black brane. Using this method, we compute the numerical spectrum of quasinormal modes associated with fluctuations of spin 0, 1 and 2, non-perturbatively in $μ / T$ . We also analytically compute the spectrum of hydrodynamic excitations in the small chemical potential limit. Then, by studying the spectral curve at complex momenta in every spin channel, we numerically find points at which hydrodynamic and non-hydrodynamic poles collide. We discuss the relation between such collision points and the convergence radius of the hydrodynamic derivative expansion. Specifically in the spin 0 channel, we find that within the range $1.1 ≲ μ / T ≲ 2$ , the radius of convergence of the hydrodynamic sound mode is set by the absolute value of the complex momentum corresponding to the point at which the sound pole collides with the hydrodynamic diffusion pole. It shows that in holographic systems at finite chemical potential, the convergence of the hydrodynamic derivative expansion in the mentioned range is fully controlled by hydrodynamic information. As the last result, we explicitly show that the relevant information about quantum chaos in our system can be extracted from the pole-skipping points of energy density response function. We find a threshold value for $μ / T$ , lower than which the pole-skipping points can be computed perturbatively in a derivative expansion.
↳ hep-thnucl-thJHEP(2020)·82 citations
17
Prompt-delayed $γ$ -ray spectroscopy of neutron-rich $^{119, 121}$ In isotopes
S. Biswas🇫🇷 · A. Lemasson🇫🇷 · M. Rejmund🇫🇷 · A. Navin🇫🇷 · Y.H. Kim🇫🇷 · C. Michelagnoli🇫🇷 · I. Stefan🇫🇷 · R. Banik🇮🇳 · P. Bednarczyk🇵🇱 · Soumik Bhattacharya🇮🇳 · S. Bhattacharyya🇮🇳 · E. Clément🇫🇷 and 14 other authors
The fusion and transfer induced fission reaction $^{9}$ Be( $^{238}$ U,~f) with 6.2 MeV/u beam energy, using a unique setup consisting of AGATA, VAMOS++ and EXOGAM detectors, was used to populate through the fission process and study the neutron-rich $^{119, 121}$ In isotopes. This setup enabled the prompt-delayed $γ$ -ray spectroscopy of isotopes in the time range of $100 ns - 200 μ s$ . In the odd- $A$ $^{119, 121}$ In isotopes, indications of a short half-life $19/ 2^{-}$ isomeric state, in addition to the previously known $25/ 2^{+}$ isomeric state, were observed from the present data. Further, new prompt transitions above the $25/ 2^{+}$ isomer in $^{121}$ In were identified along with reevaluation of its half-life. The experimental data were compared with the theoretical results obtained in the framework of large-scale shell-model calculations in a restricted model space. The $⟨ π g_{9/2} ν h_{11/2}; I \arrowvert H^\arrowvert π g_{9/2} ν h_{11/2}; I ⟩$ two-body matrix elements of residual interaction were modified to explain the excitation energies and the $B (E 2)$ transition probabilities in the neutron-rich In isotopes. The (i) decreasing trend of $E (29/ 2^{+}) - E (25/ 2^{+})$ in odd-In (with dominant configuration $π g_{9/2}^{- 1} ν h_{11/2}^{- 2}$ and maximum aligned spin of $29/ 2^{+}$ ) and (ii) increasing trend of $E (27/ 2^{+}) - E (23/ 2^{+})$ in odd-Sb (with dominant configuration $π g_{7/2}^{+ 1} ν h_{11/2}^{- 2}$ and maximum aligned spin of $27/ 2^{+}$ ) with increasing neutron number could be understood as a consequence of hole-hole and particle-hole interactions, respectively.
↳ nucl-exnucl-thPRC(2020)·4 citations
18
Misconceptions on Effective Field Theories and spontaneous symmetry breaking: Response to Ellis' article
Thomas Luu🇩🇪 · Ulf-G. Meißner🇩🇪
In an earlier paper~\cite{Luu:2019jmb} we discussed emergence from the context of effective field theories, particularly as related to the fields of particle and nuclear physics. We argued on the side of reductionism and weak emergence. George Ellis has critiqued our exposition in~\cite{Ellis:2020vij}, and here we provide our response to his critiques. Many of his critiques are based on incorrect assumptions related to the formalism of effective field theories and we attempt to correct these issues here. We also comment on other statements made in his paper. Important to note is that our response is to his critiques made in archive versions arXiv:2004.13591v1-5 [physics.hist-ph]. That is, versions 1-5 of this archive post. Version 6 has similar content as versions 1-5, but versions 7-9 are seemingly a different paper altogether (even with a different title).
↳ physics.hist-phhep-phnucl-thFound.Phys.(2020)·0 citations
19
Anisotropy fluctuation and correlation in central $α$ -clustered $^{12}$ C+ $^{197}$ Au collisions
L. Ma. Y. G. Ma · S. Zhang
In the framework of a multi-phase transport model, fluctuation and correlation of the azimuthal anisotropies in $^{12}$ C+ $^{197}$ Au collisions at $S_{N N}$ = 200 GeV are explored. Properties of the initial eccentricity and final harmonic flow fluctuation resulted from $^{12}$ C+ $^{197}$ Au collisions with Woods-Saxon configuration and triangular $α$ -clustering configurations of $^{12}$ C are investigated via scaled variance, skewness and kurtosis. Comparisons are made between results from $α$ -clustered configurations and Woods-Saxon configuration. The triangular flow fluctuation is found to have particular sensitivity in distinguishing triangular $α$ -clustering structure of $^{12}$ C. Furthermore, correlations between initial eccentricities and final flow harmonics are studied with strong multiplicity dependence observed for the correlation functions.
↳ hep-phnucl-exnucl-thPRC(2020)·22 citations
20
Constraining dense matter physics using f-mode oscillations in neutron stars
Sukrit Jaiswal · Debarati Chatterjee
In this undergraduate project, f-mode oscillations in neutron stars are used to constrain the equation of state of dense matter. For the first time, a systematic investigation of the role of nuclear saturation parameters on the mode oscillations is performed. It is found that the uncertainty in the determination of effective nucleon mass plays the most significant role in controlling the f-mode frequencies. Correlations of the frequencies with astrophysical observables relevant for asteroseismology are also investigated. Future detection of f-mode frequencies could then provide a unique way of constraining nuclear empirical parameters and therefore the behaviour of dense matter.
↳ astro-ph.HEnucl-thMDPI Physics(2021)·15 citations
21
Lattice QCD constraints on the heavy quark diffusion coefficient
Nora Brambilla🇩🇪 · Viljami Leino🇩🇪 · Peter Petreczky🇺🇸 · Antonio Vairo🇩🇪
We report progress towards computing the heavy quark momentum diffusion coefficient from the correlator of two chromo-electric fields attached to a Polyakov loop in pure SU(3) gauge theory. Using a multilevel algorithm and tree-level improvement, we study the behavior of the diffusion coefficient as a function of temperature in the wide range $1.1 < T / T_{c} < 1 0^{4}$ in order to compare it to perturbative expansions at high temperature. We find that within errors the lattice results are remarkably compatible with the next-to-leading order perturbative result.
↳ hep-lathep-phnucl-thPRD(2020)·120 citations
22
Bottomonium suppression and elliptic flow from real-time quantum evolution
Ajaharul Islam🇺🇸 · Michael Strickland🇺🇸
We compute the suppression and elliptic flow of bottomonium using real-time solutions to the Schrödinger equation with a realistic in-medium complex-valued potential. To model the initial production, we assume that, in the limit of heavy quark masses, the wave-function can be described by a lattice-smeared (Gaussian) Dirac delta wave-function. The resulting final-state quantum-mechanical overlaps provide the survival probability of all bottomonium eigenstates. Our results are in good agreement with available data for $R_{AA}$ as a function of $N_{part}$ and $p_{T}$ collected at $s_{NN} =$ 5.02 TeV. In the case of $v_{2}$ for the various states, we find that the path-length dependence of $Υ (1 s)$ suppression results in quite small $v_{2}$ for $Υ (1 s)$ . Our prediction for the integrated elliptic flow for $Υ (1 s)$ in the $10 - 90$ % centrality class is $v_{2} [Υ (1 s)] = 0.0026 \pm 0.0007$ . We additionally find that, due to their increased suppression, excited bottomonium states have a larger elliptic flow and we make predictions for $v_{2} [Υ (2 s)]$ and $v_{2} [Υ (3 s)]$ as a function of centrality and transverse momentum. Similar to prior studies, we find that it is possible for bottomonium states to have negative $v_{2}$ at low transverse momentum.
↳ hep-phnucl-thPLB(2020)·42 citations

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