Nuclear Experiment·nucl-ex

Mon·Aug 31, 2026Monday·August 31, 2026

9 papers—4 primary·5 cross-listed

01
Direct Bayesian Inference of Helicity Amplitudes from Detector-Level Scattering Data
Bhawani Singh🇺🇸 · Harut Avakian🇺🇸 · Shohini Bhattacharya🇺🇸 · Volker D. Burkert🇺🇸 · Latifa Elouadrhiri🇺🇸 · Derek I. Glazier🇬🇧 · Valery Kubarovsky🇺🇸 · Dillon Leahy🇬🇧 · Yaohang Li🇺🇸 · Richard G. Milner🇺🇸 · Yijie Wang🇺🇸
Helicity amplitudes give the most complete description of a variety of scattering reactions used in studies of strong interactions, but they cannot be measured directly: experiments record bilinear combinations of them folded through a detector response, and conventional analyses recover them through multiple stages that introduce discrete ambiguities and require a separate extraction of the absolute cross sections. Here we replace that chain with a single Bayesian inference that determines the experimentally identifiable amplitude parameters directly from detector-level measurements. A score-based diffusion model, trained on a forward simulator, provides the full posterior in each kinematic bin, with the detector response carried by the forward model and positivity of the spin-density matrix guaranteed by the parameterization. The observable amplitude content in electroproduction of final particles grows with polarization of beams and targets, providing additional sensitivity to underlying phases. In simulation, the posterior achieves empirical coverage at or above the nominal level and delivers the angular observables and the separated contributions from longitudinal and transverse photons with their correlations retained. It transfers without retraining to a realistic detector response absent from training and remains reliable in the weakly constrained nucleon-helicity-flip sector, where per-bin likelihood maximization degrades. The result is a general framework for a broad class of inverse problems, phase retrieval, quantum-state tomography, and partial-wave analysis are further instances. Its core requires only a forward simulation of the complete measurement process, instrumental effects are handled within one statistically consistent posterior, applicable across exclusive vector-meson programs at Jefferson Lab, COMPASS, HERMES, and the future Electron-Ion Collider.
nucl-exhep-ph0 citations
02
Doppler-shift attenuation method (DSAM) lifetimes in $^{54}$ Cr - a re-evaluation
Andrew E. Stuchbery🇦🇺
Background: Contemporary stopping powers for fp-shell nuclei slowing in tantalum can differ by a factor of two from the 1963 Lindhard, Scharff and Schiøtt (LSS) theory [Mat. Fys. Medd. Dan. Vid. Selsk. 33 no. 14, (1963)] used in Doppler-shift attenuation method (DSAM) lifetime measurements dating back to the 1970s. In recent work [Phys. Rev. C 113, 044306 (2026)], it was found that anomalously high collectivity in the $4_{1}^{+} \to 2_{1}^{+}$ transition of 58Fe given in the literature [Nucl. Data Sheets 111, 897 (2010)] could be traced back as due to the use of these historical stopping powers in the Doppler-shift lifetime measurements. Satisfactory agreement with shell-model calculations was obtained from a re-analysis of the measurement of Bolotin et al. [Nucl. Phys. A 311, 75 (1978)] once the stopping powers were replaced by up-to-date values. Purpose: The DSAM measurement on 54Cr by the same group [Nucl. Phys. A 337, 1 (1980)], which used the same experimental methods and procedures, is re-examined. Method: The computer code used in the original DSAM analysis has been rebuilt and upgraded with the capacity to use contemporary stopping powers. E2 transition strengths derived from the revised lifetimes are compared with shell-model calculations. Results: The lifetimes increase by 16% to 27%, with the larger increase generally corresponding to shorter lifetimes where electronic stopping dominates. Conclusions: Revised lifetimes, based on current stopping powers, imply E2 transition rates between states up to the 6 $_{1}^{+}$ state in 54Cr that compare well with shell-model calculations. The lifetime data together with branching ratios and the shell-model calculations strongly suggest revision of the spins assigned to the levels at 3.786 (currently (4) $^{+}$ ) and 4.043 MeV (currently 5 $^{+}$ ). These levels are suggested to be the 5 $_{1}^{+}$ and 6 $_{2}^{+}$ states, respectively.
nucl-exnucl-th0 citations
03
Lifetime measurements in neutron-rich odd-A yttrium isotopes ( $^{93 - 99}$ Y): Investigation of shape coexistence and the intertwined quantum phase transition
A. Pfeil🇩🇪 · N. Gavrielov🇫🇷 · U. Köster🇫🇷 · Y. H. Kim🇫🇷 · N. Cieplicka-Oryńczak🇵🇱 · J. Dudouet🇫🇷 · A. Esmaylzadeh🇩🇪 · Ł. W. Iskra🇵🇱 · M. Ley🇩🇪 · J.-M. Régis🇩🇪 · D. Reygadas🇫🇷 · J. Jolie🇩🇪
Lifetimes of 16 excited states in the neutron-rich odd- $A$ nuclei $^{93 - 99}$ Y were measured using fast-timing $γ$ - $γ$ coincidence spectroscopy with fast scintillation detectors at the LOHENGRIN recoil separator. Particular attention is given to the region around $N \approx 59$ , where rapid changes in nuclear deformation and shape coexistence occur. The lifetimes, determined using the generalized centroid difference method, are compared with interacting boson-fermion model calculations with configuration mixing, in which the odd- $A$ yttrium isotopes are described as a proton coupled to a bosonic core containing normal and intruder configurations. The results provide new constraints on theoretical descriptions of shape coexistence and structural evolution in neutron-rich nuclei near $A \approx 100$ , particularly for odd- $A$ systems where experimental information remains limited.
nucl-exnucl-th0 citations
04
The role of strangeness and baryon enhancement in heavy-quark hadronisation from pp to Pb $-$ Pb collisions with ALICE
Fabrizio Chinu🇮🇹
In this contribution, a combined study of charm-meson and charm-baryon production with ALICE is presented. The $Λ_{c}^{+} / D^{0}$ ratio in pp collisions at $s = 13.6$ TeV and the first measurement of the nuclear modification factor of $Ξ_{c}^{0}$ baryons in Pb $-$ Pb collisions at $s_{NN} = 5.02$ TeV are reported. Furthermore, measurements of the $D_{s}^{+} / D^{+}$ production ratio from low-multiplicity pp collisions at $s = 13.6$ TeV to Pb $-$ Pb collisions at $s_{NN} = 5.36$ TeV are presented. Lastly, the first measurement of the $p_{T}$ -differential $D_{s1} (2536)^{+} / D_{s}^{+}$ yield ratio is shown.
nucl-ex0 citations
05
CGC and saturation approach: Impact-parameter dependent model of perturbative QCD and combined HERA data
Michael Roa🇨🇱 · José Garrido🇨🇱 · Miguel Guevara🇨🇱
In this paper we confront the CGC/saturation approach of Ref.~\cite{CLMS} with the experimental combined HERA data and obtain its parameters. The model includes two features that are in accordance with our theoretical knowledge of deep inelastic scattering. These consist of: \textit{i}) the use of analytical solution for the non-linear Balitsky-Kovchegov (BK) evolution equation and \textit{ii}) the exponential behavior of the saturation momentum on the impact parameter $b$ -dependence, characterized by $Q_{s}$ $\propto exp (- mb)$ which reproduces the correct behavior of the scattering amplitude at large $b$ in accord with Froissart theorem. The model results are then compared to data at small- $x$ for the structure-function of the proton $F_{2}$ , the longitudinal structure function $F_{L}$ , the charm structure function $F_{2}^{c c ˉ}$ , the exclusive vector meson ( $J / ψ, ϕ, ρ$ ) production and Deeply Virtual Compton Scattering (DVCS). We obtain a good agreement for the processes in a wide kinematic range of $Q^{2}$ at small- $x$ . Our results provide a strong guide for finding an approach, based on Color Glass Condensate/saturation effective theory for high energy QCD, to make reliable predictions from first principles and for forthcoming experiments like the Electron-Ion Collider and the LHeC.
↳ hep-phhep-exnucl-exnucl-thPRD(2024)·5 citations
06
Spectroscopy of 211,213,215Pb isotopes and seniority properties
Larry Zamick · Praveen Srivastava🇮🇳
We first consider lead isotopes with valence neutrons in the g9/2shell. We especially compare 211Pb (n=3), 213Pb (n=5) and 215Pb (n=7), 213Pb being at mid-shell. Motivated by the fact the J = 21/2+ and J =3/2+ states are pure seniority v=3 states for both n=3 and n=5, we compare the energy splitting E(J=21/2+)-E(J=3/2+) for various interactions. We then discuss the position of the lowest J=3/2+ state in both n=3 and n=5, although, this state has not been found experimentally. Calculations with configurations beyond g9/2 are also considered. We next address the fact that the J=21/2+ state is isomeric for both n=3 and n=5.
↳ nucl-thnucl-exIJMPE(2026)·0 citations
07
Microscopic Realization of Topologically Quantized Alignment in Fast-Rotating Nuclei
Ganlong Ding · Sibo Wang🇨🇳 · Hiroyuki Tajima · Daisuke Suzuki🇯🇵 · Jing Peng🇨🇳 · Haozhao Liang🇯🇵
We present the first quantitative microscopic realization of topologically quantized alignment in a finite nuclear system. The realization is obtained by exact diagonalization of a cranking seniority model, with the first Chern number evaluated over the sphere of cranking-axis orientations and analyzed together with the orientation-averaged alignment and cranking-frame configuration probabilities. The Chern number changes in integer steps as the system evolves from initially paired configurations to increasingly aligned configurations. A new intermediate phase is found in which the Chern number is already nonzero while the alignment continues to evolve toward its quantized value. We show that this deviation originates from the competition among pairing, axial quadrupole splitting, and Coriolis mixing. Thus, our microscopic approach reveals a more nuanced emergence of topologically quantized alignment in realistic nuclei, providing a quantitative stepping stone toward experimental investigations.
↳ nucl-thnucl-ex0 citations
08
Magnetic Moments and Radiative Transitions of the $T_{cc} (3875)^{+}$ and its partner states
Jing Wu🇨🇳 · Yi-Kun Wang🇨🇳 · Kai-Bao Chen🇨🇳 · Yan-Rui Liu🇨🇳 · Jian-Bo Cheng🇨🇳 · Wei-Hua Yang🇨🇳
We systematically investigate the magnetic moments (MMs) and radiative decay widths of S-wave doubly heavy tetraquark states based on chromomagnetic interaction (CMI). They provide a complementary probe to distinguish compact from molecule structures in addition to the mass spectrum and strong decay properties. Using the CMI eigenvectors, we compute the MMs and M1 transition rates for the tetraquarks in the compact configuration. We predict the MM of the observed $T_{cc} (3875)^{+}$ with $I (J^{P}) = 0 (1^{+})$ to be 0.45 $μ_{N}$ when treating it as a compact tetraquark state, whereas the MM of the $0 (1^{+})$ $D D^{*}$ molecule is about $- 0.07 μ_{N}$ . Five radiative transition channels related to the $T_{cc} (3875)^{+}$ are identified with widths ranging from $6.07$ keV to $306.37$ keV. Our results show that the MMs of the $J^{P} = 1^{+}$ $b c q ˉ q ˉ^{'}$ ( $q / q^{'} = u, d, s$ ) and $J^{P} = 1^{+}$ $QQ n ˉ s ˉ$ ( $Q = b, c; n = u, d$ ) states are influenced by the diquark-spin mixing. Through the analyses of radiative transitions between different tetraquark states, we find that such processes in the $QQ n ˉ n ˉ^{'}$ , $QQ s ˉ s ˉ$ , and $b c n ˉ s ˉ$ cases may serve to reveal the tetraquark structures of the initial or final states. We also define the magnetic coupling matrices characterizing the MMs of the tetraquark system with $J^{P} = 1^{+}$ , with which the range of MM can be constrained. The present study provides a valuable reference point for the search of exotic states in future particle physics experiments.
↳ hep-phhep-exhep-latnucl-ex+10 citations
09
Effect of Thermal Broadening on Light Hadron Production in Heavy-Ion Collisions
Q'inich Coc🇩🇪 · Oscar Garcia-Montero🇪🇸 · Aleksas Mazeliauskas🇩🇪
The measured hadron yields in heavy-ion collisions are well described by thermal particle production at temperatures close to the QCD pseudo-critical transition. However, if particles are produced in thermal equilibrium, then the in-medium effects, e.g., broadening of their spectral functions, must be taken into account. In this work, we study for the first time the effect of the thermal broadening of the light vector-meson spectral functions on light hadron production in heavy-ion collisions. We generalize the efficient resonance decay framework FastReso to resonances with finite-width spectral functions. We then compute the pion, kaon and proton spectra from the decays of hadron resonances for in-medium and vacuum spectral functions. We perform a simultaneous blast-wave fit with decay feed-down to measured particle spectra in central Pb-Pb and Xe-Xe collisions at the LHC. We find an increase in pion spectra at low momenta, from including thermally broadened $ρ$ and $ω$ mesons. Additional pion yield from finite-resonance widths reduces the commonly observed discrepancy between models and data, but does not completely resolve the soft pion puzzle in heavy-ion collisions.
↳ hep-phnucl-exnucl-th0 citations

Affiliations

first authorsco-authorsvia INSPIRE