PaperPanorama

Nuclear Experiment·nucl-ex

Fri·Sep 18, 2026

7 papers—1 primary·6 cross-listed

All7Primary1Cross-lists6
  1. 01

    Measurements of Cross Sections with the CLAS12 Detector for from 2.4-8.0 GeV and from 1.4-2.1 GeV

    K. Neupane · R.W. Gothe · D.S. Carman · V.I. Mokeev · A.G. Acar · P. Achenbach · J.S. Alvarado · W.R. Armstrong · H. Avakian · N.A. Baltzell · L. Barion · M. Bashkanov and 136 other authors

    This paper reports exclusive cross sections for the reaction using the CLAS12 detector at Jefferson Laboratory. The extractions of fully integrated and nine single-differential cross sections are presented for the first time for photon virtualities from 2.4 to 8.0 GeV and center-of-mass energies from 1.4 to 2.1 GeV, which covers a large part of the nucleon resonance region. These data considerably extend the kinematic reach of previous measurements from CLAS that covered up to 5.0 GeV. Exclusive cross section measurements are of particular importance for the extraction of resonance electrocouplings across the spectrum, especially in the mass range above 1.6 GeV where several resonances decay preferentially to the final states. The electrocouplings with extended coverage expected from these new data will enable an improved understanding of the emergence of mass and structure in the transition from the strongly coupled toward the perturbative QCD regime.

    nucl-ex
  2. 02

    Internal structure of exotic hadron candidate (980) by using fragmentation functions

    S. Kumano🇨🇳

    High-energy hadron reactions could be appropriate to find exotic evidences in exotic hadron candidates instead of global observables such as masses, spins, parities, and decay widths, because quarks and gluons are explicit degrees of freedom. One of possible methods is to use fragmentation functions (FFs) by taking advantage of properties on favored and disfavored functions, which corresponds to valence-quark and sea-quark distributions in parton distribution functions. Looking at these FFs, we should be able to find the exotic nature as the valence-quark distributions reflect the nature of valence constituents as shown in the pion and the proton. Recent accurate measurements of the (980) FFs by the Belle collaboration made it possible to find its internal configuration by looking at their second moments and functional forms. Global analysis results of the (980) FFs indicate that its internal configuration looks like , which is different from a tetraquark or -molecule like configuration suggested from low-energy studies. This fact indicates that the internal configuration looks different depending on the energy. At low energies, it looks like a tetraquark ( molecule) hadron, but it looks like a hadron at high energies. In the similar way, some exotic hadron candidates could become ordinary or hadrons at high energies, although they are interpreted as exotic at low energies. This kind of new idea should be tested by future experiments especially by looking at energy or momentum dependencies in high energy hadron reactions.

    ↳ hep-ph0 citations
  3. 03

    Femtoscopic Correlation Functions in Density Operator Representation

    Hao-Nan Liu · Duo-Lun Ge · Zhi-Wei Liu · Jun-Xu Lu · Li-Sheng Geng

    Femtoscopic correlation functions (CFs) have been increasingly used to extract strong interactions between pairs of unstable particles, but their physical soundness has recently been questioned. To answer this, we formulate CFs at the operator level, with the observed subsystem described by a reduced density operator and subsequent dynamics absorbed into an effective measurement operator. The Koonin-Pratt form is recovered under four well-motivated reductions. The formulation makes explicit that the source-side and interaction-side representations must be consistently matched, and motivates an operational convention in which a measured reference correlation establishes a compatible source--interaction pairing that can be extended to other pairs for CF-to-CF predictions.

    ↳ quant-phhep-exhep-phnucl-ex+1
  4. 04

    Binning-Independent Bayesian Analysis of Time-Dependent Perturbed Angular Distribution data

    Franziskus von Spee

    We propose a new approach for analyzing Time-Dependent Perturbed Angular Distribution data. In this, a likelihood is constructed with the help of conditional probabilities of single events and binning of time data is avoided. This likelihood is used in a Bayesian framework to calculate the posterior probability density function for the factor of interest. This approach is compared to more traditional approaches that use binned data by analyzing simulated datasets. In many cases the resulting posterior probability densities are observed to be multimodal and the results can thus often not be summarized with a single Gaussian approximation. We find that results from the new approach are more reliable for low-statistics datasets.

    ↳ stat.MEnucl-exphysics.data-an
  5. 05

    Three-State Mixing as a Phenomenological Framework for Multiple Shape Coexistence

    Marco Siciliano

    Shape coexistence represents one of the most striking manifestations of competing collective and single-particle degrees of freedom in atomic nuclei. While the coexistence and mixing of two configurations can be described within the well-established Two-State Mixing framework, the observation of three or more competing structures requires a more general treatment. In this work, we introduce a Three-State Mixing (3SM) model in which three intrinsic configurations are related to the physical states through an rotation. The framework establishes a direct connection between experimental observables, configuration-mixing amplitudes, and intrinsic properties, while the experimentally known excitation energies allow the corresponding effective Hamiltonian and interaction strengths to be reconstructed. The model is applied to the low-lying structure of Sn using electromagnetic matrix elements recently determined through a comprehensive Coulomb-excitation measurement. The analysis identifies three intrinsic configurations characterized by spherical, weakly oblate, and strongly deformed triaxial shapes, together with substantial configuration mixing among the physical states. The present formulation provides a general phenomenological framework for investigating systems in which multiple configurations coexist and strongly interact.

    ↳ nucl-thnucl-ex
  6. 06

    Generalized parton distributions: Theory meets experiment

    Yuxun Guo · Xiangdong Ji · Yao Ji · Jialu Zhang

    Over the past three decades, generalized parton distributions (GPDs) have emerged as one of the most active and important areas of research in nucleon structure and quantum chromodynamics (QCD). Since the last comprehensive review two decades ago, substantial progress has been made in experimental measurements of hard exclusive processes, such as deeply virtual Compton scattering and near-threshold production, as well as in increasingly sophisticated phenomenological analyses of GPDs that enable three-dimensional nucleon tomography. Theoretical advances in perturbative coefficient functions, scale evolutions, and kinematic and power corrections have considerably improved the precision of GPD phenomenology, while new hard exclusive processes for probing GPDs have been explored. More interestingly, lattice QCD can now directly access GPDs at fixed parton momentum fractions and skewness through large-momentum expansions, in addition to the traditional calculations of their moments, or generalized form factors. Significant progress has also been made in exploring the QCD energy-momentum tensor that encodes fundamental information on the nucleon's mass distribution, complete spin structure, and spatial distributions of momentum current and color-Lorentz forces acting on quarks and gluons.

    ↳ hep-phhep-exhep-latnucl-ex+1
  7. 07

    Gaussian characterization of two-neutron halo nuclei

    A. Deltuva · M. Gattobigio · D. Jurčiukonis · A. Kievsky

    The halo nucleon-core system is, by definition, a shallow state nucleus. The nucleon, in most cases a neutron, is loosely bound to the other nucleons forming the core. Accordingly, the system is located inside the universal window; the halo nucleon most likely resides far from the rest of the nucleons, showing a remarkable insensitivity to details of the interaction with the core. The system can be described using a simple nucleon-core interaction, and this description can be extended to the nucleon-nucleon-core system. Specifically, treating the neutron-core and the neutron-neutron-core systems with a Gaussian interaction as a reference, we show trajectories inside the universal window governed by interaction parameters determined from low-energy observables, such as the neutron-core binding energy, scattering length, and effective range. In this way, we can relate properties of different halo nuclei that might seem uncorrelated. In particular, we determine the three-body parameter, the binding momentum at the unitary limit, and show that the two-neutron halo nuclei emerge from that limit following a linear trajectory depending on the neutron-core range.

    ↳ nucl-thnucl-exPhysical Review C 114, 034001 (2026)

Affiliations

first authorsco-authorsvia INSPIRE