Nuclear Theory·nucl-th

Wednesday·June 5, 2024

10 papers—3 primary·7 cross-listed

01
[Submitted on 3 Jun 2024]
A universal reduced basis for the calibration of covariant energy density functionals
Amy L. Anderson · J. Piekarewicz
The reduced basis method is used to construct a "universal" basis of Dirac orbitals that may be applicable throughout the nuclear chart to calibrate covariant energy density functionals. Relative to our earlier work using the non-relativistic Schrödinger equation, the Dirac equation adds an extra layer of complexity due to the existence of negative energy states. However, once this problem is mitigated, the resulting reduced basis is able to accurately and efficiently reproduce the high-fidelity model at a fraction of the computational cost. We are confident that the resulting reduced basis will serve as a foundational element in developing rapid and accurate emulators. In turn, these emulators will play a critical role in the Bayesian optimization of covariant energy density functionals.
Comments:
9 pages, 7 figures, to be submitted to Physical Review C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2406.01747 [pdf]
PRC(2024)·2 citations
02
[Submitted on 4 Jun 2024]
Towards accurate nuclear mass tables in covariant density functional theory
A. Taninah · B. Osei · A.V.Afanasjev · U.Perera · S.Teeti
The current investigation focuses on detailed analysis of the anchor based optimization approach (ABOA), its comparison with alternative global fitting protocols and on the global analysis of the truncation of basis effects in the calculation of binding energies. It is shown that ABOA provides a solution which is close to that obtained in alternative approaches but at small portion of their computational time. The application of softer correction function after few initial iterations of ABOA stabilizes and speeds up its convergence. For the first time, the numerical errors in the calculation of binding energies related to the truncation of bosonic and fermionic bases have been globally investigated with respect of asymptotic values corresponding to the infinite basis in the framework of covariant density functional theory (CDFT). These errors typically grow up with the increase of the mass and deformation of the nuclei. To reduce such errors in bosonic sector below 10 keV for almost all nuclei with proton number $Z < 120$ one should truncate the bosonic basis at $N_{B} = 28$ instead of presently used $N_{B} = 20$ . The reduction of the errors in binding energies due to the truncation of the fermionic basis in CDFT is significantly more numerically costly. For the first time it is shown that the pattern and the speed of the convergence of binding energies as a function of the size of fermionic basis given by $N_{F}$ depend on the type of covariant energy density functional. The use of explicit density dependence of the meson-nucleon coupling constants or point couplings slows down substantially the speed of convergence of binding energies as a function of $N_{F}$ . A new procedure for finding the asymptotic values of binding energies is suggested in the present paper: it allows better control of numerical errors.
Comments:
26 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2406.01896 [pdf]
PRC(2024)·10 citations
03
[Submitted on 4 Jun 2024]
Eikonal calculation of (p,3p) cross sections for neutron-rich nuclei
M. Gómez-Ramos
In this work, we present the first, to our knowledge, theoretical description of two-proton removal reactions with proton target $(p, 3 p)$ for medium-mass nuclei at intermediate energies and present cross sections for the different bound states of the residual nucleus with two fewer protons. The description of the reaction assumes two sequential ``quasifree'' collisions between the target and removed protons and considers eikonal propagation in between. The formalism is applied to the reactions $^{12} C (p, 3 p)^{10} Be$ , $^{28} Mg (p, 3 p)^{26} Ne$ and $^{54} Ca (p, 3 p)^{52} Ar$ , finding reasonable agreement to experimental data for the $^{12}$ C target and an overestimation of a factor $\sim 3$ for the more neutron-rich and $^{54}$ Ca, which is similar to the results found in two-proton knockout experiments with $^{9}$ Be and $^{12}$ C targets.
Comments:
10 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2406.02138 [pdf]
PRC(2024)·1 citation
04
[Submitted on 3 Jun 2024] (cross-list from hep-ph)
Color Glass Condensate meets High Twist Expansion
Yu Fu🇺🇸 · Zhong-Bo Kang🇺🇸 · Farid Salazar🇺🇸 · Xin-Nian Wang🇨🇳 · Hongxi Xing🇨🇳
We establish the correspondence between two well-known frameworks for QCD multiple scattering in nuclear media: the Color Glass Condensate (CGC) and the High-Twist (HT) expansion formalism. We argue that a consistent matching between both frameworks, in their common domain of validity, is achieved by incorporating the sub-eikonal longitudinal momentum phase in the CGC formalism, which mediates the transition between coherent and incoherent scattering. We perform a detailed calculation and analysis of direct photon production in proton-nucleus scattering as a concrete example to establish the matching between HT and CGC up to twist-4, including initial- and final-state interactions, as well as their interferences. The techniques developed in this work can be adapted to other processes in electron-nucleus and proton-nucleus collisions, and they provide a potential avenue for a unified picture of dilute-dense dynamics in nuclear media.
Comments:
35 pages, 12 figures, 1 table. v2: matches the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2406.01684 [pdf]
PRD(2025)·13 citations
05
[Submitted on 3 Jun 2024] (cross-list from hep-ph)
Exploring doubly-heavy tetraquarks in constituent-quark-model based meson-meson coupled-channels approach
P. G. Ortega🇪🇸 · D. R. Entem🇪🇸 · F. Fernandez🇪🇸 · J. Segovia🇪🇸
The LHCb Collaboration announced in 2021 the discovery of a new tetraquark-like state, named $T_{cc}^{+}$ , with minimum quark content $cc u ˉ d ˉ$ , close to the $D^{0} D^{*+}$ threshold. This has motivated countless theoretical works trying to identify the dynamics which is responsible of the formation of such state; in particular, the one performed by us in Ref. \cite{Ortega:2022efc}, where a $D^{0} D^{*+}$ molecular candidate whose mass, width, scattering length and effective ranges are in reasonable agreement with experimental measurements. We explore herein the possibility of having $T_{cc}^{+}$ partners in all doubly-heavy tetraquark sectors, considering doubly represented light antiquarks $u$ , $d$ or $s$ , and taking into account all possible spin-parity quantum numbers. The computation is done using a constituent-quark-model based meson-meson coupled-channels framework which has been tested many times in the last fifteen years describing conventional heavy mesons and baryons, their coupling with hadron-hadron thresholds but also in exploring its application to compact multiquark structures. The advantage of using an approach with such a relatively large history is that it allows us to make predictions because all the parameters have already been constrained from our previous works. Then, from this perspective, we present a parameter-free model-dependent prediction of doubly-heavy tetraquarks that may be partners of the discovered $T_{cc}^{+}$ state.
Comments:
8 pages, 1 figure, 6 tables. arXiv admin note: text overlap with arXiv:2211.06118
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2406.01697 [pdf]
PRD(2024)·5 citations
06
[Submitted on 3 Jun 2024] (cross-list from physics.plasm-ph)
Anomalous thermal relaxation in warm ion plasmas
David Barba-González · Conrado Albertus · M. Ángeles Pérez-García
We perform microscopic simulations of the thermal relaxation of warm neutral plasmas of astrophysical importance. Using Molecular Dynamics we study the thermal relaxation of a hot neutral fluid of finite-size neutron-rich ions kept in a fixed-wall cool box. We show how the interplay among particle size, Yukawa interaction range and density are key to understand the features of the time-dependent thermal relaxation curve $T (t)$ . We show that, under certain conditions, these systems exhibit faster cooling from increasingly larger initial temperature values. They also display non-Newtonian thermal behavior, including oscillations, that can be {\it effectively} interpreted as the consequence of the existence of a non-trivial system memory function. Finally, we consider the impact of multicomponent admixtures in the simulated system. We discuss these results and their possible extensions to astrophysical scenarios, where screened plasmas with Yukawa-like electrostatic potentials are usually involved.
Comments:
8 pages, 4 figures. Accepted in MNRAS
Subjects:
Plasma Physics (physics.plasm-ph); Nuclear Theory (nucl-th)
arXiv:
2406.01700 [pdf]
MNRAS(2025)·3 citations
07
[Submitted on 3 Jun 2024] (cross-list from physics.comp-ph)
Validating Automated Resonance Evaluation with Synthetic Data
Oleksii Zivenko · Noah A. W. Walton · William Fritsch · Jacob Forbes · Amanda M. Lewis · Aaron Clark · Jesse M. Brown · Vladimir Sobes
The integrity and precision of nuclear data are crucial for a broad spectrum of applications, from national security and nuclear reactor design to medical diagnostics, where the associated uncertainties can significantly impact outcomes. A substantial portion of uncertainty in nuclear data originates from the subjective biases in the evaluation process, a crucial phase in the nuclear data production pipeline. Recent advancements indicate that automation of certain routines can mitigate these biases, thereby standardizing the evaluation process, reducing uncertainty and enhancing reproducibility. This article contributes to developing a framework for automated evaluation techniques testing, emphasizing automated fitting methods that do not require the user to provide any prior information. This approach simplifies the process and reduces the manual effort needed in the initial evaluation stage. It highlights the capability of the framework to validate and optimize subroutines, targeting the performance analysis and optimization of the fitting procedure using high-fidelity synthetic data (labeled experimental data) and the concept of a fully controlled computational experiment. An error metric is introduced to provide a clear and intuitive measure of the fitting quality by quantifying the accuracy and performance across the specified energy. This metric sets a scale for comparison and optimization of routines or hyperparameter selection, improving the entire evaluation process methodology and increasing reproducibility and objectivity.
Comments:
39 pages, 12 figures; As a follow-up to arXiv:2303.09698 and arXiv:2402.14122
Subjects:
Computational Physics (physics.comp-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); physics.med-ph (physics.med-ph)
arXiv:
2406.01754 [pdf]
0 citations
08
[Submitted on 4 Jun 2024] (cross-list from hep-ph)
Quasifragmentation functions in the massive Schwinger model
Sebastian Grieninger🇺🇸 · Ismail Zahed🇺🇸
We introduce the concept of the quark quasifragmentation function (qFF) using an equal-time and spatially boosted form of the Collins-Soper fragmentation function where the out-meson fragment is replaced by the current asymptotic condition. We derive the qFF for a fermion in two-dimensional quantum electrodynamics (QED2) using the Kogut-Susskind Hamiltonian after a mapping onto spin qubits in a spatial lattice with open boundary conditions. This form is suitable for quantum computations. We compute the qFF by exact diagonalization of the spin Hamiltonian. The results are compared to the qFF following from the Drell-Levy-Yan result for QED2, both at strong and weak coupling, and to two-dimensional quantum chromodynamics in the lowest Fock approximation.
Comments:
10+3 pages; 7+2 figures; v2: matches version published in PRD; title change to conform with APS conventions
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2406.01891 [pdf]
PRD(2024)·21 citations
09
[Submitted on 4 Jun 2024] (cross-list from hep-th)
On the non-uniqueness of the energy-momentum and spin currents
Rajeev Singh🇷🇴
The macroscopic energy-momentum and spin densities of relativistic spin hydrodynamics are obtained from the ensemble average of their respective microscopic definitions (quantum operators). These microscopic definitions suffer from ambiguities, meaning that one may obtain different forms of symmetric energy-momentum tensor and spin tensor through pseudogauge transformations (or, in other words, Belinfante improvement procedure). However, this ambiguity may be fixed if we obtain these currents using Noether's second theorem instead of widely used Noether's first theorem. The second theorem fixes the super-potential determined by local symmetry, thereby selecting a unique physically consistent pseudogauge. In this article, we use Noether's second theorem to derive energy-momentum and spin currents without the need of pseudogauge transformations for free Dirac massive particles with spin one-half.
Comments:
Accepted version
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2406.02127 [pdf]
Int.J.Mod.Phys.A(2026)·9 citations
10
[Submitted on 4 Jun 2024] (cross-list from quant-ph)
Quantum states from normalizing flows
Scott Lawrence · Arlee Shelby · Yukari Yamauchi
We introduce an architecture for neural quantum states for many-body quantum-mechanical systems, based on normalizing flows. The use of normalizing flows enables efficient uncorrelated sampling of configurations from the probability distribution defined by the wavefunction, mitigating a major cost of using neural states in simulation. We demonstrate the use of this architecture for both ground-state preparation (for self-interacting particles in a harmonic trap) and real-time evolution (for one-dimensional tunneling). Finally, we detail a procedure for obtaining rigorous estimates of the systematic error when using neural states to approximate quantum evolution.
Comments:
7 pages, 3 figures
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
arXiv:
2406.02451 [pdf]
5 citations

Affiliations

first authorsco-authorsvia INSPIRE