Nuclear Theory·nucl-th

Wednesday·January 18, 2023

15 papers—5 primary·10 cross-listed

06
[Submitted on 13 Jan 2023] (cross-list from quant-ph)
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.
Comments:
19 pages
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
arXiv:
2301.05735 [pdf]
Int.J.Mod.Phys.A(2024)·6 citations
07
[Submitted on 14 Jan 2023] (cross-list from quant-ph)
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.
Comments:
30 pages, 17 figures, v3/v4: minor modifications
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
arXiv:
2301.05976 [pdf]
PRC(2023)·51 citations
08
[Submitted on 15 Jan 2023] (cross-list from hep-ph)
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.
Comments:
version published in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2301.06154 [pdf]
PRD(2023)·9 citations
09
[Submitted on 16 Jan 2023] (cross-list from hep-ph)
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.
Comments:
6 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2301.06441 [pdf]
CPC(2023)·2 citations
10
[Submitted on 16 Jan 2023] (cross-list from astro-ph.HE)
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.
Comments:
Accepted Phys. Rev. Lett. (29 September 2023)
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2301.06515 [pdf]
PRL(2023)·48 citations
11
[Submitted on 17 Jan 2023] (cross-list from hep-th)
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.
Comments:
6 pages, 2 figures
Subjects:
High Energy Physics — Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
arXiv:
2301.06651 [pdf]
PLB(2023)·62 citations
12
[Submitted on 17 Jan 2023] (cross-list from hep-th)
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.
Comments:
9 pages, 8 figures, published version
Subjects:
High Energy Physics — Theory (hep-th); Statistical Mechanics (cond-mat.stat-mech); Nuclear Theory (nucl-th)
arXiv:
2301.06703 [pdf]
PRD(2024)·4 citations
13
[Submitted on 17 Jan 2023] (cross-list from nucl-ex)
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.
Comments:
21 pages, 22 figures, revised version accepted for publication in Phys. Rev. C
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2301.06835 [pdf]
PRC(2023)·6 citations
14
[Submitted on 17 Jan 2023] (cross-list from hep-ph)
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.
Comments:
22 pages, 6 figures, published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2301.06940 [pdf]
EPJC(2023)·8 citations
15
[Submitted on 17 Jan 2023] (cross-list from hep-ph)
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.
Comments:
6 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2301.07049 [pdf]
30 citations

Affiliations

first authorsco-authorsvia INSPIRE