Nuclear Experiment·nucl-ex

Fri·Sep 4, 2026Friday·September 4, 2026

9 papers—3 primary·6 cross-listed

01
First Measurement of Near-Threshold J/{\psi} Photoproduction on the Neutron
R. Tyson🇬🇧 · D.G. Ireland🇬🇧 · B. McKinnon🇬🇧 · P. Chatagnon🇫🇷 · V. Kubarovsky🇺🇸 · S. Stepanyan🇺🇸 · A.G. Acar🇬🇧 · P. Achenbach🇺🇸 · J.S. Alvarado🇫🇷 · M.J. Amaryan🇺🇸 · W.R. Armstrong🇺🇸 · H. Avakian🇺🇸 and 128 other authors
We report the first measurement of the total and t-differential cross sections for near-threshold J/ $ψ$ photoproduction on the neutron, obtained with the CLAS12 detector at the Thomas Jefferson National Accelerator Facility. The measurements, performed using a liquid-deuterium target, also provide the incoherent total and t-differential cross sections on the bound proton, enabling the first direct comparison of near-threshold J/ $ψ$ photoproduction on bound protons and neutrons. Interpreted within Vector Meson Dominance, holographic QCD, and GPD-based frameworks, the data allow for the investigation of the gluonic structure of bound nucleons. A comparison with free proton results reveals hints of modifications to the gluon structure of nucleons in the nuclear medium, within the assumptions of the extraction and on the underlying production mechanism. The comparison of bound neutron and bound proton cross sections provides new constraints on the near-threshold J/ $ψ$ production mechanism, which is crucial in order to establish J/ $ψ$ photoproduction as a probe of the nucleon's gluonic structure.
nucl-exhep-ex0 citations
02
Measurement of the forward angle $^{12}$ C+ $^{12}$ C fragmentation differential cross sections at 62 MeV/nucleon
G. Guo🇨🇳 · G. Casini🇮🇹 · B. H. Sun🇨🇳 · S. Barlini🇮🇹 · A. Camaiani🇮🇹 · C. Frosin🇮🇹 · I. Lombardo🇮🇹 · O. Lopez🇫🇷 · S. Piantelli🇮🇹 · I. Tanihata🇯🇵 · S. Terashima🇨🇳 · S. Valdré🇮🇹 and 22 other authors
The present work reports on high-precision measurements of forward-angle fragmentation differential cross sections for the [12]C +[12] C reaction at 62 MeV/nucleon using the FAZIA array. Angular distributions for fragments from Z = 1 to 6 were extracted in the range 2 <= theta_lab <= 8 degrees. Particle identification was achieved by combining the Delta E - E technique with Pulse Shape Analysis, and precise energy calibrations were performed. The results show that for heavier fragments, the angular distributions are better described by the Van Bibber formulation than by the Goldhaber model, consistent with the dominance of a wide component from dissipative processes in the measured angular range. Notably, alpha particles exhibit an anomalously narrow angular distribution, likely originating from the intrinsic cluster structure of [12]C. Comparisons with existing data at the same incident energy show very good agreement, with a more complete set of species reported here, while a kinematic scaling is proposed to compare our data with previous experimental data at 50 and 95 MeV/nucleon.
nucl-exPRC(2026)·0 citations
03
Neutron dynamics in the fusion of neutron-rich O ions with $^{12}$ C
A. Leon · H. Desilets🇺🇸 · Rohit Kumar🇺🇸 · J. Samol · Z. Berend · R.T. deSouza🇺🇸 · C. Ciampi🇫🇷 · D. Ackermann🇫🇷 · A. Chbihi🇫🇷 · M. Basson🇺🇸 · S. Brown🇺🇸 · K.W. Brown🇺🇸 and 9 other authors
The fusion excitation function for $^{21}$ O + $^{12}$ C was measured for the first time and compared to the fusion of less neutron-rich isotopes. The impact of valence neutrons in the d $_{5/2}$ shell on the fusion excitation function is examined. The experimental data manifest a clear dependence of the extracted barrier height, V $_{B}$ , and barrier position, R $_{B}$ on neutron excess. To assess the role of dynamics the experimental data are compared with both density constrained frozen Hartree Fock (DCFHF) and density constrained time-dependent Hartree Fock (DCTDHF) theories.
nucl-ex0 citations
04
Constraining tensor force terms with the charge radii difference of mirror-pair nuclei
Yan Ya · Na Tang · Rong An🇨🇳
Charge radii differences of mirror partner nuclei provide an alternative probe to pin down the interaction components in asymmetric nuclear matter. In this work, the differences in the charge radii of almost spherical mirror-paired nuclei $^{54}$ Ni- $^{54}$ Fe and $^{36}$ Ca- $^{36}$ S are used to constrain the magnitude of tensor terms in the Skyrme interactions. The calculated results suggest that a linear correlation can be found between the difference of charge radii of mirror partner nuclei and the adopted strengths of the triplet-odd and triplet-even tensor components. Besides, it suggests that charge radii differences of mirror-paired nuclei are more sensitive to the adopted strengths of the triplet-odd parameter $U$ rather than the triplet-even parameter $T$ . Combining the quantitative constraint strengths of the triplet-even tensor part obtained from the magnetic dipole (M1) excitations, the charge-exchange Gamow-Teller (GT) states, and the spin-dipole (SD) excitations, the triplet-odd strengths are further constrained for the SLy5 as well as SGII effective interactions. This provides an alternative approach to constrain the appropriate magnitude of tensor force.
↳ nucl-thnucl-exPRC(2026)·0 citations
05
Measurement of Differential Cross Sections and Integrated Luminosity using Proton-Proton Elastic Scattering with HADES at T = 4.53 GeV and T = 1.60 GeV
HADES Collaboration: R. Abou Yassine🇩🇪 · J. Adamczewski-Musch🇩🇪 · G. A. Appagere🇸🇪 · M. Becker🇩🇪 · A. Blanco🇧🇷 · C. Blume🇩🇪 · M. Bohman🇸🇪 · Y. Bondar🇵🇱 · L. Chlad🇨🇿 · I. Ciepał🇵🇱 · S. Deb🇫🇷 · M. D. Doncel Monasterio🇸🇪 and 115 other authors
This work presents an investigation of elastic proton-proton scattering based on data collected with the recently upgraded HADES detector using beams of protons with kinetic energies of $T = 4.53$ GeV and $T = 1.60$ GeV impinging on a liquid hydrogen target. This is the first measurement emerging from the upgraded detector setup, including a Forward Detector with straw-tube tracking planes designed for the PANDA experiment. The well-constrained two-body kinematic relations of elastic scattering have been exploited to study the detector alignment, the beam alignment, and to provide the final measurement of the beam energy. In addition, the recorded luminosity of the experiment has been determined by normalizing the HADES data in a range of the squared four-momentum transfer $t$ that overlaps with measurements by previous experiments worldwide. Furthermore, the differential cross sections have been determined over a large range of $t$ from which the slope parameter $B$ is extracted, yielding $B = 8.98 \pm 0.3$ (GeV/ $c$ ) $^{- 2}$ and $7.3 \pm 0.1$ (GeV/ $c$ ) $^{- 2}$ at $T = 4.53$ GeV and $1.60$ GeV, respectively. This contribution to the world database on elastic proton-proton scattering provides input to theoretical modeling and serves as a reference for luminosity determinations by future experiments in the same energy range.
↳ hep-exnucl-ex0 citations
06
Leading-Neutron Electroproduction at HERA and the EIC: Sullivan Process, Target Fragmentation, and Pion PDFs
Wen-Chen Chang🇹🇼 · Chia-Yu Hsieh🇹🇼 · Satyajit Puhan🇹🇼
Leading-neutron electroproduction measurements from the H1 and ZEUS experiments at HERA have been used to constrain pion parton distribution functions (PDFs) at small momentum fractions within the Sullivan one-pion-exchange (OPE) framework, complementing large- $x_{π}$ constraints from pion-induced Drell--Yan measurements. Previous analyses have focused primarily on the region of large neutron longitudinal momentum fraction, $x_{L}$ , where contributions from deep-inelastic scattering (DIS) target fragmentation are suppressed. In this work, we use the \textsc{Pythia} event generator to model the target-fragmentation contribution and show that its combination with the OPE contribution reproduces the main features of the HERA leading-neutron data over the full measured $x_{L}$ range without introducing additional ad hoc normalization factors. This result demonstrates the potential of incorporating a broader range of leading-neutron data into future global analyses, thereby extending sensitivity to smaller pion momentum fractions $x_{π}$ . We investigate the model dependence associated with the pion--nucleon vertex form factor and show that the HERA data are sensitive to different target-fragmentation treatments implemented in \textsc{Pythia}. Finally, we present projections for leading-neutron production at the future U.S. Electron-Ion Collider (EIC), identifying beam-energy configurations and kinematic regions that provide enhanced sensitivity to pion structure while suppressing DIS target-fragmentation contributions.
↳ hep-phhep-exnucl-ex0 citations
07
CGC-py: A Monte Carlo Event Generator for Gluon Saturation Physics
Haowu Duan🇨🇳 · Cong Yi🇨🇳 · Si-Wei Dai🇨🇳 · Shu-Yi Wei🇨🇳 · Wenbin Zhao🇨🇳 · Liang Zheng🇨🇳
We develop CGC-py, a Monte Carlo event generator for deep-inelastic scattering. It couples the full Color Glass Condensate (CGC) cross section for $γ^{*} p (A) \to q q ˉ + X$ to a Parton-Branching transverse-momentum-dependent backward initial-state shower, while \textsc{Pythia}~8 handles final-state radiation and hadronization. CGC-py retains the complete target-elastic and target-inelastic contributions without taking the back-to-back correlation limit, allowing single- and di-hadron observables to be generated consistently from the same event sample. We validate the generator through an analytic closure test of the single-inclusive quark spectrum and a comparison of charged-hadron spectra in $e p$ collisions with H1 data, finding excellent agreement. The predicted nuclear modification factor $R_{e Au}^{h}$ shows the expected saturation pattern: suppression at low $p_{T}^{*}$ followed by a rise toward unity at higher $p_{T}^{*}$ . A comparison with a \textsc{Pythia}~6 baseline, together with an $x_{g}$ -rescaling study, indicates that small- $x$ CGC evolution and collinear DGLAP dynamics contribute comparably to the growth of the dihadron away-side width with energy. Genuine saturation-driven broadening emerges only at the highest energies considered. Within CGC-py, $e Au$ collisions exhibit an enhanced away-side width and a suppressed back-to-back yield relative to $e p$ collisions. These nuclear effects remain modest over EIC kinematics, motivating measurements at the most forward accessible kinematics and the use of complementary observables to maximize sensitivity to gluon saturation.
↳ hep-phhep-exnucl-exnucl-th1 citation
08
Magnetic Dipole Hyperfine Constants of 15 Energy Levels in $^{169}$ Tm II Determined by Collinear Laser Fluorescence Spectroscopy
Hendrik Bodnar · Kristian König🇩🇪 · Wilfried Nörtershäuser🇩🇪
We present measurements of the hyperfine structure, transition frequencies and relative intensities in 14 lines of 169Tm+ ions starting from the $4 f^{13} (^{2} F_{7/2}^{o}) 6 s_{1/2} (7/2, 1/2)_{3, 4}^{o}$ levels. The magnetic dipole hyperfine ( $A$ ) constant of all 15 involved ionic levels are determined, 14 of which have sub-MHz accuracy. For five levels no previous measurements were reported, while all others are in excellent agreement with the literature and improve on the previous accuracy by typically 1 - 2 orders of magnitude. We compare transition strengths and include improved transition frequencies. These results are useful for the quantum computing community, modelling of Tm $^{+}$ abundances in stellar spectra, as well as for an ongoing measurement program on short-lived Tm isotopes at ISOLDE/CERN.
↳ physics.atom-phnucl-ex0 citations
09
TQ4Q2.0 Fragmentation Functions for Fully Heavy Tetraquark Production
Francesco Giovanni Celiberto🇪🇸
We investigate the fragmentation dynamics underlying the production of fully heavy tetraquarks by means of the TQ4Q2.0 collinear FF set, covering scalar ( $0^{++}$ ), axial-vector ( $1^{+-}$ ), and tensor ( $2^{++}$ ) configurations. The fragmentation inputs are determined within NRQCD factorization for the complete set of relevant partonic channels and are subsequently evolved across heavy-flavor thresholds through the HF-NRevo scheme. Perturbative uncertainties associated with fragmentation-scale variations are consistently propagated together with nonperturbative effects encoded in color-composite long-distance matrix elements. Attention is devoted to the axial-vector sector, whose fragmentation pattern makes it especially sensitive to intrinsic-charm contributions at LHC and FCC energies. TQ4Q2.0 therefore provides an uncertainty-aware framework for exploring fully heavy tetraquark production over a broad kinematic range and for connecting exotic-hadron spectroscopy with the partonic structure of the proton.
↳ hep-phhep-exnucl-exnucl-th0 citations

Affiliations

first authorsco-authorsvia INSPIRE