Nuclear Theory·nucl-th

Wednesday·January 18, 2023

15 papers—5 primary·10 cross-listed

01
QED corrections to elastic electron-nucleus scattering beyond the first-order Born approximation
D.H.Jakubassa-Amundsen🇩🇪
A potential for the vertex and self-energy correction is derived from the first-order Born theory. The inclusion of this potential in the Dirac equation, together with the Uehling potential for vacuum polarization, allows for a nonperturbative treatment of these QED effects within the phase-shift analysis. Investigating the 12C and 208Pb targets, a considerable deviation of the respective cross-section change from the Born results is found, which becomes larger with increasing momentum transfer. Estimates for the correction to the beam-normal spin asymmetry are also provided. For the 12C nucleus, dispersion effects are considered as well.
nucl-th1 citation
02
Spin-Flavor SU(6) Symmetry for Baryon-Baryon Interactions
Makoto Oka🇯🇵
Short-range parts of the baryon-baryon ( $B B$ ) interactions are analyzed from the spin-flavor $S U (6)_{s f} \supset S U (3)_{f} \times S U (2)_{s}$ symmetry viewpoint. Due to the Pauli principle of quarks, the symmetry structure of the wave functions is restricted at short distances. Consequently, the $B B$ states with the same spin-flavor quantum numbers may be reduced into one or a few spin-flavor states. Such reduction causes repulsion and/or suppression of transitions at short distances. We show that the observed suppression of the $Ξ N \to ΛΛ$ conversion can be explained following the above argument. It is also applied to the suppression of the $Σ N$ to $Λ N$ conversion in the spin 1 and isospin 1/2 channel. Furthermore, the effects of the color-magnetic interaction (CMI), which prefers flavor antisymmetric states, to the Pauli-allowed states are discussed.
nucl-thhep-lathep-ph3 citations
03
Machine learning in nuclear physics at low and intermediate energies
Wanbing He · Qingfeng Li · Yugang Ma · Zhongming Niu · Junchen Pei · Yingxun Zhang
Machine learning is becoming a new paradigm for scientific research in various research fields due to its exciting and powerful capability of modeling tools used for big-data processing task. In this mini-review, we first briefly introduce different methodologies of the machine learning algorithms and techniques. As a snapshot of many applications by machine learning, some selected applications are presented especially for low and intermediate energy nuclear physics, which include topics on theoretical applications in nuclear structure, nuclear reactions, properties of nuclear matter as well as experimental applications in event identification/reconstruction, complex system control and firmware performance. Finally, we also give a brief summary and outlook on the possible directions of using machine learning in low-intermediate energy nuclear physics and possible improvements in ML algorithms.
nucl-thnucl-exSCPMA(2023)·109 citations
04
Effective field theory analysis of the Coulomb breakup of the one-neutron halo nucleus 19C
Pierre Capel🇩🇪 · Daniel R. Phillips🇺🇸 · Andrew Andis🇺🇸 · Mirko Bagnarol🇮🇱 · Behnaz Behzadmoghaddam🇮🇷 · Francesca Bonaiti🇩🇪 · Rishabh Bubna🇩🇪 · Ylenia Capitani🇮🇹 · Pierre-Yves Duerinck🇧🇪 · Victoria Durant🇩🇪 · Niklas Döpper🇩🇪 · Aya El Boustani🇪🇸 and 20 other authors
We analyse the Coulomb breakup of 19C measured at 67A MeV at RIKEN. We use the Coulomb-Corrected Eikonal (CCE) approximation to model the reaction and describe the one-neutron halo nucleus 19C within Halo Effective Field Theory (EFT). At leading order we obtain a fair reproduction of the measured cross section as a function of energy and angle. The description is insensitive to the choice of optical potential, as long as it accurately represents the size of 18C. It is also insensitive to the interior of the 19C wave function. Comparison between theory and experiment thus enables us to infer asymptotic properties of the ground state of 19C: these data put constraints on the one-neutron separation energy of this nucleus and, for a given binding energy, can be used to extract an asymptotic normalisation coefficient (ANC). These results are confirmed by CCE calculations employing next-to-leading order Halo EFT descriptions of 19C: at this order the results for the Coulomb breakup cross section are completely insensitive to the choice of the regulator. Accordingly, this reaction can be used to constrain the one-neutron separation energy and ANC of 19C.
nucl-thnucl-exEPJA(2023)·5 citations
05
Strangeness thermodynamic instabilities in hot and dense nuclear matter
A. Lavagno🇮🇹 · D. Pigato🇮🇹
We explore the presence of thermodynamic instabilities and, con\-se\-quen\-tly, the realization of a pure hadronic phase transition in the hot and finite baryon density nuclear matter. The analysis is performed by means of an effective relativistic mean-field model with the inclusion of hyperons, $Δ$ -isobars, and the lightest pseudoscalar and vector meson degrees of freedom. The Gibbs conditions on the global conservation of baryon number and zero net strangeness in symmetric nuclear matter are required. Similarly to the liquid-gas phase transition, we show that a phase transition, characterized by mechanical instabilities (due to fluctuations on the baryon number) and chemical-diffusive instabilities (due to fluctuations on the strangeness number), can take place for a finite range of $Δ$ -meson coupling constants, compatible with different experimental constraints. The hadronic phase transition, which presents similar features to the quark-hadron phase transition, is characterized by different strangeness content during the mixed phase and, consequently, by a sensible variation of the strange anti-particle to particle ratios.
nucl-thEPJA(2022)·6 citations
06
Classical Entanglement and Entropy
Haowu Duan🇺🇸 · Alex Kovner🇺🇸 · Vladimir V. Skokov🇺🇸
Motivated by recent discussions of entanglement in the context of high energy scattering, we consider the relation between the entanglement entropy of a highly excited state of a quantum system and the classical entanglement entropy of the corresponding classical system. We show on the example of two weakly coupled harmonic oscillators, that the two entropies are equal. Quantum mechanically, the reduced density matrix which yields this entropy is close to the maximally entangled state. We thus observe that the nature of entanglement in this type of state is purely classical.
↳ quant-phnucl-thInt.J.Mod.Phys.A(2024)·6 citations
07
Quantum Simulations in Effective Model Spaces (I): Hamiltonian Learning-VQE using Digital Quantum Computers and Application to the Lipkin-Meshkov-Glick Model
Caroline E. P. Robin🇩🇪 · Martin J. Savage🇺🇸
The utility of effective model spaces in quantum simulations of non-relativistic quantum many-body systems is explored in the context of the Lipkin-Meshkov-Glick model of interacting fermions. We introduce an iterative hybrid-classical-quantum algorithm, Hamiltonian learning variational quantum eigensolver (HL-VQE), that simultaneously optimizes an effective Hamiltonian, thereby rearranging entanglement into the effective model space, and the associated ground-state wavefunction. HL-VQE is found to provide an exponential improvement in Lipkin-Meshkov-Glick model calculations, compared to a naive truncation without Hamiltonian learning, throughout a significant fraction of the Hilbert space. Quantum simulations are performed to demonstrate the HL-VQE algorithm, using an efficient mapping where the number of qubits scales with the $lo g$ of the size of the effective model space, rather than the particle number, allowing for the description of large systems with small quantum circuits. Implementations on IBM's QExperience quantum computers and simulators for 1- and 2-qubit effective model spaces are shown to provide accurate and precise results, reproducing classical predictions. This work constitutes a step in the development of entanglement-driven quantum algorithms for the description of nuclear systems, that leverages the potential of noisy intermediate-scale quantum (NISQ) devices.
↳ quant-phnucl-thPRC(2023)·51 citations
08
The Nambu-Goto string in QCD: Dipole interactions, scattering and entanglement
Yizhuang Liu🇵🇱 · Maciej A. Nowak🇵🇱 · Ismail Zahed🇺🇸
We revisit some aspects of the stringy approach to dipole-dipole interactions, scattering and entanglement in QCD, using the Nambu-Goto (NG) string, without recourse to holography. We first show that the potential between two static dipoles exchanging closed NG strings is attractive at all separations. Underlining the exchange there is an emergent entropy, that is dominated by the tachyon at large separation, and vanishes at short separation, a measure of the confinement-deconfinement transition. The same tachyon is dominant in the scattering amplitude, as a correlator of two Wilson loops for two fixed dipole-like hadrons separated at large rapidity gap, where the contribution of the worldsheet fermions is included. While the tachyon causes the mean string bit density to grow exponentially with the rapidity, the total scattering cross section still satisfies the Froissart bound by quantum shadowing. The stringy scattering exchange also carries an entanglement entropy, that saturates when the bound is reached. For hadrons with varying dipole sizes, the tachyon exchange takes place in hyperbolic space in the conformal limit. The result for the full S-matrix is reminiscent of the one from Mueller $^{'}$ s evolved dipole wavefunction, for the total dipole-dipole cross section in perturbative QCD.
↳ hep-phhep-latnucl-thPRD(2023)·9 citations
09
Production of $X_{cs c ˉ s ˉ}$ in heavy ion collisions
Yuanyuan Hu🇨🇳 · Hui Zhang🇨🇳
The yields of $X_{cs c ˉ s ˉ}$ with its two possible configurations, i.e., the hadronic molecular state and tetraquark state, for Pb-Pb collisions at $s_{N N} = 5.02 TeV$ is studied. A volume effect is found from the centrality distribution of $X_{cs c ˉ s ˉ}$ , which could help to distinguish the inner structure of $X_{cs c ˉ s ˉ}$ . We also show the rapidity and the transverse momentum distributions of $X_{cs c ˉ s ˉ}$ production as well as its elliptic flow coefficient as a function of the transverse momentum.
↳ hep-phnucl-thCPC(2023)·2 citations
10
Gravitational Waves from a Core g-Mode in Supernovae as Probes of the High-Density Equation of State
Pia Jakobus🇦🇺 · Bernhard Müller🇦🇺 · Alexander Heger🇦🇺 · Shuai Zha🇨🇳 · Jade Powell🇦🇺 · Anton Motornenko🇩🇪 · Jan Steinheimer🇩🇪 · Horst Stoecker🇩🇪
Using relativistic supernova simulations of massive progenitor stars with a quark-hadron equation of state (EoS) and a purely hadronic EoS, we identify a distinctive feature in the gravitational-wave signal that originates from a buoyancy-driven mode (g-mode) below the proto-neutron star convection zone. The mode frequency lies in the range $200 ≲ f ≲ 800 Hz$ and decreases with time. As the mode lives in the core of the proto-neutron star, its frequency and power are highly sensitive to the EoS, in particular the sound speed around twice saturation density.
↳ astro-ph.HEastro-ph.SRnucl-thPRL(2023)·48 citations
11
Bounds on transport from hydrodynamic stability
L. Gavassino🇺🇸
It was recently shown that the dispersion relations describing singularities of retarded two-point functions in causal quantum field theories always satisfy the fundamental inequality $Im ω \leq ∣ Im k ∣$ , and that several rigorous bounds on transport coefficients follow directly from such inequality. Here, we prove that the same inequality, $Im ω \leq ∣ Im k ∣$ , is a necessary condition for a fluid theory to be covariantly stable (i.e. stable in all frames of reference). Hence, the same bounds on transport that follow from causality in quantum field theory also emerge as stability conditions within relativistic hydrodynamics. This intimate connection between bounds from causality and bounds from stability stems from the fact that covariant stability is possible only in the presence of causality. As a quick application, we show that fluids with luminal speed of sound have vanishing viscosities.
↳ hep-thgr-qcmath-phmath.MP+1PLB(2023)·62 citations
12
Non-Gaussianity from Schwinger-Keldysh Effective Field Theory
Shu Lin🇨🇳 · Yanyan Bu🇨🇳 · Chang Lei🇨🇳
We present a systematic treatment of non-Gaussianity in stochastic systems using the Schwinger-Keldysh effective field theory framework, in which the non-Gaussianity is realized as nonlinear terms in the fluctuation field. We establish two stochastic formulations of the Schwinger-Keldysh effective field theory, with those nonlinear terms manifested as multiple non-Gaussian noises in the Langevin equation and as higher order diffusive terms in the Fokker-Planck equation. The equivalence of the stochastic formulations with the original Schwinger-Keldysh effective field theory is demonstrated with non-trivial examples for arbitrary non-Gaussian parameters. The stochastic formulations will be more flexible and effective in studying non-equilibrium dynamics. We also reveal an ambiguity when coarse-graining time scale and non-Gaussian parameters vanish simultaneously, which may be responsible for the unphysical divergence found in perturbative analysis.
↳ hep-thcond-mat.stat-mechnucl-thPRD(2024)·4 citations
13
Measurement of the $^{236}$ U fission cross section and angular distributions of fragments from fission of $^{235}$ U and $^{236}$ U in the neutron energy range of 0.3-500 MeV
A. S. Vorobyev · A. M. Gagarski · O. A. Shcherbakov · L. A. Vaishnene · A. L. Barabanov · T. E. Kuz'mina
The $^{236}$ U fission cross section and the angular distributions of fragments from fission of $^{235}$ U and $^{236}$ U were measured for incident neutron energies from 0.3 MeV to 500 MeV on the time-of-flight spectrometer of the neutron complex GNEIS at the NRC "Kurchatov Institute" -- PNPI. Fission fragments were registered using position-sensitive low-pressure multiwire counters. In the neutron energy range above 20 MeV, the angular distributions of $^{236}$ U fission fragments were measured for the first time. The fission cross section of $^{236}$ U $(n, f)$ was measured relative to the fission cross section of $^{235}$ U $(n, f)$ , which is an accepted international standard. The obtained data are compared with the results of other experimental works. Theoretical calculations of the fission cross section and the anisotropy of angular distribution of fission fragments for the $^{236}$ U $(n, f)$ reaction performed within the framework of our approach are presented and discussed.
↳ nucl-exnucl-thPRC(2023)·6 citations
14
Accessing Compton Form Factors at the Electron Ion Collider in China: An Impact study on $Im E$
Xu Cao🇨🇳 · Jinlong Zhang🇨🇳
We estimate the impact of asymmetry measurements of Deeply Virtual Compton Scattering (DVCS) with transversely polarized proton beam taken at a future Electron Ion Collider in China (EicC) on the extraction of Compton Form Factors (CFFs). The CFFs extracted from an analysis based on artificial neural-network approach are reweighted by means of pseudo-data generated in the expected kinematic region of EicC. We find a remarkable improvement in the extraction of CFF $Im E$ , especially at the range of parton momentum fraction $x \sim$ 0.01, thus hinting for a future experimental probe of the parton orbital angular momentum. This work casts a glance at a practical implementation of Bayesian reweighting method on CFFs' impact study.
↳ hep-phnucl-thEPJC(2023)·8 citations
15
Many-body neutrino flavor entanglement in a simple dynamic model
Joshua D. Martin🇺🇸 · A. Roggero🇮🇹 · Huaiyu Duan🇺🇸 · J. Carlson🇺🇸
Dense neutrino gases form in extreme astrophysical sites, and the flavor content of the neutrinos likely has an important impact on the subsequent dynamical evolution of their environment. Through coherent forward scattering among neutrinos, the flavor content of the gas evolves under a time-dependent potential which can be modeled in a quantum many-body formalism as an all-to-all coupled spin-spin interaction. This two-body potential generically introduces entanglement and greatly complicates the study of these systems. In this work we study the evolution of the quantum many-body problem as well as the typically employed mean-field approximation to it for a small number of neutrinos ( $N = 16$ ). We consider randomly chosen one- and two-body couplings in the Hamiltonian, and the resulting evolution of several initial product states. We subsequently compare many-body and mean-field predictions for one-body observables, and we consider one- and two-body entanglement to assess under what conditions the many-body and mean-field predictions are likely to disagree. Except for a special category of prototypical initial conditions, we find that the typically employed mean-field approximation is insufficient to capture the evolution of one-body operators in the systems we consider. We also observe a loss of coherence in one- and two-body trace-reduced subsystems which suggests that the evolution may be well approximated as a classical mixture of separable states.
↳ hep-phastro-ph.HEnucl-th30 citations

Affiliations

first authorsco-authorsvia INSPIRE