Nuclear Theory·nucl-th

Wednesday·December 11, 2024

12 papers—3 primary·9 cross-listed

04
Efficacious qubit mappings for quantum simulations of the $^{12}$ C rotational band
Darin C. Mumma🇺🇸 · Zhonghao Sun🇺🇸 · Alexis Mercenne🇺🇸 · Kristina D. Launey🇺🇸 · Soorya Rethinasamy🇺🇸 · James A. Sauls🇺🇸
Solving atomic nuclei from first principles places enormous demands on computational resources, which grow exponentially with increasing number of particles and the size of the space they occupy. We present first quantum simulations based on the variational quantum eigensolver for the low-lying structure of the $^{12}$ C nucleus that provide acceptable bound-state energies even in the presence of noise. We achieve this by taking advantage of two critical developments. First, we utilize an almost perfect symmetry of atomic nuclei that, in a complete symmetry-adapted basis, drastically reduces the size of the model space. Second, we use the efficacious Gray encoding, for which it has been recently shown that it is resource efficient, especially when coupled with a near band-diagonal structure of the nuclear Hamiltonian.
↳ quant-phnucl-th2024 IEEE Computer Society Annual Symposi…·0 citations
05
Sim-to-real supervised domain adaptation for radioisotope identification
Peter Lalor · Henry Adams · Alex Hagen
Machine learning has the potential to improve the speed and reliability of radioisotope identification using gamma spectroscopy. However, meticulously labeling an experimental dataset for training is often prohibitively expensive, while training models purely on synthetic data is risky due to the domain gap between simulated and experimental measurements. In this research, we demonstrate that supervised domain adaptation can substantially improve the performance of radioisotope identification models by transferring knowledge between synthetic and experimental data domains. We consider two domain adaptation scenarios: (1) a simulation-to-simulation adaptation, where we perform multi-label proportion estimation using simulated high-purity germanium detectors, and (2) a simulation-to-experimental adaptation, where we perform multi-class, single-label classification using measured spectra from handheld lanthanum bromide (LaBr) and sodium iodide (NaI) detectors. We begin by pretraining a spectral classifier on synthetic data using a custom transformer-based neural network. After subsequent fine-tuning on just 64 labeled experimental spectra, we achieve a test accuracy of 96% in the sim-to-real scenario with a LaBr detector, far surpassing a synthetic-only baseline model (75%) and a model trained from scratch (80%) on the same 64 spectra. Furthermore, we demonstrate that domain-adapted models learn more human-interpretable features than experiment-only baseline models. Overall, our results highlight the potential for supervised domain adaptation techniques to bridge the sim-to-real gap in radioisotope identification, enabling the development of accurate and explainable classifiers even in real-world scenarios where access to experimental data is limited.
↳ cs.LGnucl-thNucl.Instrum.Meth.A(2026)·3 citations
06
Investigation of $π N$ contributions to nucleon matrix elements
Constantia Alexandrou🇨🇾 · Giannis Koutsou🇨🇾 · Yan Li🇨🇾 · Marcus Petschlies🇩🇪 · Ferenc Pittler🇨🇾
We investigate an improved method to extract nucleon matrix elements from lattice 3-point functions using a generalized eigenvalue problem (GEVP) with nucleon and pion-nucleon interpolating fields. Our method avoids the computation of the costly three-point functions that have pion-nucleon interpolators at both source and sink. We demonstrate that excited state contamination from $N π$ is minimized in nucleon matrix elements of the scalar, vector, pseudoscalar, axial, and tensor currents and discuss our results based on a physical-point ensemble with a pion mass value of 131 MeV. We find that the GEVP is most significant for the isovector pseudoscalar and axial currents.
↳ hep-lathep-phnucl-thPoS(2025)·2 citations
07
Toward a Direct Measurement of Partial Restoration of Chiral Symmetry at J-PARC E16 via Density-induced Chiral Mixing
Ren Ejima🇯🇵 · Philipp Gubler🇯🇵 · Chihiro Sasaki🇯🇵 · Kenta Shigaki🇯🇵
The degeneracy of chiral partners is an ideal signal for measuring the restoration of the spontaneously broken chiral symmetry in QCD. In this work, we investigate the observability of the $ϕ$ - $f_{1} (1420)$ degeneracy in the J-PARC E16 experiment, which measures di-electrons emitted from 30 GeV pA collisions. We for this purpose make use of an effective Lagrangian approach, which naturally incorporates the broken charge-conjugation symmetry in nuclear matter and the ensuing anomaly-induced mixing between vector and axial-vector mesons, to compute the spectral function relevant for the experimental measurement. The real-time dynamics of the pA collision is obtained from a transport simulation. Including experimental background and resolution effects on top of that, we find that a signal of the $ϕ$ - $f_{1} (1420)$ mixing can be observed around 2.5 $σ$ with the Run2 statistics planned for the J-PARC E16 experiment with an ideal mixing strength.
↳ hep-phnucl-thPRC(2025)·6 citations
08
Implementation and investigation of electron-nucleus scattering in the \textsc{NEUT} neutrino event generator
Seisho Abe🇯🇵
Understanding nuclear effects is essential for improving the sensitivity of neutrino oscillation measurements. Validating nuclear models solely through neutrino scattering data is challenging due to limited statistics and the broad energy spectrum of neutrinos. In contrast, electron scattering experiments provide abundant high-precision data with various monochromatic energies and angles. Since both neutrinos and electrons interact via electroweak interactions, the same nuclear models can be applied to simulate both interactions. Thus, high-precision electron scattering data is essential for validating the nuclear models used in neutrino experiments. To enable this, the author has introduced a new electron scattering framework in the \textsc{NEUT} neutrino event generator, covering two interaction modes: quasielastic (QE) and single pion production. \textsc{NEUT} predictions of QE agree well with numerical calculations, supporting the validity of this implementation. From comparisons with \textsc{NEUT} predictions and inclusive electron scattering data, the momentum-dependent removal energy correction is derived, addressing effects beyond the plane wave impulse approximation. This correction is applied to neutrino interactions, observing significant changes in charged lepton kinematics. Notably, the reconstructed neutrino energy distribution shows a peak shift of approximately 20--30\,MeV, which is crucial for accurately measuring neutrino oscillation parameters.
↳ hep-phhep-exnucl-thPRD(2025)·12 citations
09
Electromagnetic form factors of hyperons in the timelike region: A short review
Ling-Yun Dai🇨🇳 · Johann Haidenbauer🇩🇪 · Ulf-G. Meißner🇩🇪
We review recent experimental and theoretical results for the electromagnetic form factors of hyperons (Y) in the timelike region, accessible in the reactions $e^{+} e^{-} \to Y ˉ Y$ . Specifically, we focus on the final states $Λ ˉ Λ$ , $Λ ˉ Σ^{0}$ / $Σ ˉ^{0} Λ$ , $Σ ˉ Σ$ , $Ξ ˉ Ξ$ , and $Ω ˉ Ω$ . The $Λ ˉ_{c} Λ_{c}$ system is also discussed.
↳ hep-phhep-exnucl-thChin.Phys.Lett.(2025)·10 citations
10
Three-dimensional integral Faddeev equations without a certain symmetry
Mikhail Egorov
The approach of direct integration of the three-dimensional Faddeev equations with respect to the breakup T-matrix in momentum space for three bodies of different masses is presented. The Faddeev equations are written out explicitly without the requirement for symmetry or antisymmetry of two-body t matrices, taking into account the difference in the masses of three interacting particles. An algorithm for the algebraic search for non-relativistic wave functions of a system of three bodies of different masses is described. A significant change in the domain of logarithmic singularities of the integral kernels of the Faddeev equations from the choice of masses of interacting particles is demonstrated.
↳ quant-phnucl-thFew Body Syst.(2025)·2 citations
11
On the quantum numbers of the $X (1880)$
Qin-He Yang🇨🇳 · Ling-Yun Dai🇨🇳 · Ulf-G. Meißner🇩🇪
We study the properties of the $X (1880)$ , the structure around the $p ˉ p$ threshold that appears in the $3 (π^{+} π^{-})$ invariant mass spectrum in the decay process of $J / ψ \to γ 3 (π^{+} π^{-})$ . Nucleon-antinucleon rescattering is taken into account in our analysis, and the decay amplitude of $J / ψ \to γ 3 (π^{+} π^{-})$ can be obtained by the distorted wave Born approximation. With these amplitudes, we analyze the contributions to the $X (1880)$ from different partial waves. Our analysis suggests that the $X (1880)$ should be isoscalar $0^{-+}$ , and it is generated by the threshold behavior.
↳ hep-phnucl-thPRD(2026)·4 citations
12
Probing nonperturbative transverse momentum dependent PDFs with chiral perturbation theory: the $d ˉ - u ˉ$ asymmetry
Marston Copeland🇺🇸 · Thomas Mehen🇺🇸
We use chiral perturbation theory to study the long distance regime of transverse momentum dependent parton distribution functions (TMD PDFs). Chiral corrections to the TMD PDFs are computed from proton to pion/baryon splittings. For consistent power counting, we find that the fraction of the proton's momentum that a pion may carry must be kept small. We make predictions for a $d ˉ - u ˉ$ asymmetry in the proton's TMD PDFs and find that the effective theory gives a natural exponential suppression of the TMD PDF at long distances. We then explore the effects that additional nonperturbative physics may have on the TMD $d ˉ - u ˉ$ asymmetry.
↳ hep-phnucl-th4 citations

Affiliations

first authorsco-authorsvia INSPIRE