Nuclear Experiment·nucl-ex

Tue·Sep 15, 2026Tuesday·September 15, 2026

10 papers—5 primary·5 cross-listed

01
Measurement of $^{75} As (n, γ)^{76} As$ reaction relevant to 0 $ν β β$ decay searches of $^{76} Ge$ and astrophysical $s$ -process temperatures
Yu-Bing Li · Zhen-Dong An · Wei Jiang🇨🇳 · Cheng Li · Yu-Gang Ma🇨🇳 · Jie Ren🇨🇳 · Xi-Chao Ruan🇨🇳 · Rui-Rui Fan🇨🇳 · Jing-Yu Tang🇨🇳 · Xiang-Zhou Cai🇨🇳 · Hong-Wei Wang🇨🇳 · Chen-Chen Guo🇨🇳 and 4 other authors
The cross sections and resonance structures of $^{75} As$ (n, $γ$ ) $^{76} As$ reaction are critical to the neutrinoless double- $β$ (0 $ν β β$ ) decay searches of $^{76} Ge$ , the $s$ -process nucleosynthesis of nuclear astrophysics, and Neutron Resonance Capture Analysis for determining the elemental and isotopic composition of archaeological and cultural heritage. We report a high-precision measurement of the $^{75} As$ neutron capture cross sections from 1~eV to 1~MeV, performed at the Back-n facility of the China Spallation Neutron Source using the Time-of-Flight method. In the resolved resonance region, nineteen resonance structures of $^{75} As$ (n, $γ$ ) $^{76} As$ reaction have been discovered for the first time, and inconsistencies between evaluated libraries has been resolved. Resonance parameters for the newly observed structures were extracted with the $R$ -matrix code SAMMY. These findings will help refine the theoretical predictions of half-lives and decay constants for the double- $β$ decay searches of $^{76} Ge$ . Astrophysical Maxwellian-averaged cross sections were calculated based on the averaged cross sections in the unresolved resonance region. And the $^{75} As$ (n, $γ$ ) $^{76} As$ reaction rates were derived over the astrophysically relevant temperature range in both the main and weak $s$ -processes nucleosynthesis. The present reaction rates deviate significantly from the recent theoretical predictions, and the uncertainties are significantly reduced.
nucl-ex0 citations
02
Low-energy collective structure of $^{92, 94}$ Zr and $^{94}$ Mo from ( $e, e^{'}$ ) and ( $p, p^{'}$ ) scattering I. Experimental results
C. Walz · O. Burda · L.M. Donaldson · R.W. Fearick🇿🇦 · S.V. Förtsch · H. Fujita🇯🇵 · P. von Neumann-Cosel🇩🇪 · R. Neveling🇿🇦 · N. Pietralla🇩🇪 · A. Richter · F.D. Smit · C. Stahl · J.A. Swartz🇺🇸
This is the first of two papers discussing a new signature of quadrupole mixed-symmetry states in the vibrational nuclei $^{92, 94}$ Zr and $^{94}$ Mo based on proton and neutron transition densities derived from the comparison of inelastic electron and proton scattering experiments. Results of the $(e, e^{'})$ and $(p, p^{'})$ experiments on these nuclei as well as $(p, p^{'})$ data for other potential cases $^{96}$ Mo and $^{70}$ Zn are presented. Spin and parity quantum numbers of excited states are assigned based on angular distributions from the proton scattering data in comparison to calculations employing form factors from the collective model in distorted-wave Born approximation. Possible candidates of one-phonon fully symmetric and mixed-symmetry states as well as members of two-phonon multiplets are identified.
nucl-ex0 citations
03
Low-energy collective structure of $^{92, 94}$ Zr and $^{94}$ Mo from ( $e, e^{'}$ ) and ( $p, p^{'}$ ) scattering II. Signatures of mixed-symmetry states and origin of collectivity
C. Walz · L.M. Donaldson · P. von Neumann-Cosel🇩🇪 · N. Pietralla🇩🇪 · F.D. Smit
This is the second of two papers discussing a new experimental signature of mixed-symmetry states (MSS) in the vibrational nuclei $^{92, 94}$ Zr and $^{94}$ Mo based on proton and neutron transition densities. Quasiparticle-phonon model calculations for these nuclei are extensively tested by comparison to ground-state properties, energies and moments of excited states, transition probabilities between them, and the momentum transfer dependence in $(e, e^{'})$ and $(p, p^{'})$ reactions. The overall very good agreement permits the extraction of information on the wave functions of the MSS and their fully symmetric (FSS) counterparts. MSS can be identified by a sign change between the leading proton and neutron two-quasiparticle configurations compared to the FSS. Possible candidates for $2^{+}$ , $3^{-}$ , and $4^{+}$ MSS are identified. The modification of proton and neutron transition densities, which can be derived from a combined analysis of inelastic electron and proton scattering, by the sign change provide a new experimental signature of MSS. The collectivity of ground-state excitations of predominantly one-phonon FSS and MSS is generated to a large extent by the coupling to high-lying states forming giant resonances with the same spin and parity.
nucl-exnucl-th0 citations
04
Hadron photoproduction experiments in LEPS2
N. Muramatsu🇨🇳 · A. O. Tokiyasu🇯🇵 · T. A. Hashimoto🇯🇵
In the LEPS2 facility constructed at SPring-8, hadron photoproduction experiments have been carried out by using a photon beam with high linear polarization in the tagged energy range of 1.3-2.4 GeV. The BGOegg and Solenoid experiments are alternately running with large-acceptance detector setups, which have been prepared by focusing on the measurement of gamma-rays and charged particles, respectively. These two projects have covered a wide range of hadron physics research, including the search for in-medium meson mass modification, the baryon resonance spectroscopy, the studies on exotic hadrons, and so on. This article reviews the physics programs, the obtained results, and the future prospects in the LEPS2 facility.
nucl-exhep-ex0 citations
05
Photon-induced $J / ψ$ as a linearly polarized probe of collision geometry in relativistic heavy-ion collisions
STAR Collaboration
In relativistic heavy-ion collisions, the linear polarization of quasi-real photons can correlate the spin orientation of photon-induced vector mesons with the collision geometry. To explore this sensitivity, we present the first measurement of the decay angular distribution of photon-induced $J / ψ$ with respect to the event plane in heavy-ion collisions with hadronic overlap. The analysis uses Ru+Ru and Zr+Zr collisions at a nucleon--nucleon center-of-mass energy of $s_{NN} = 200$ GeV recorded by STAR. After correcting for the finite event-plane resolution and subtracting the residual hadronic contribution, we extract a negative second-order modulation, $A_{2}^{phot} = - 0.39 \pm 0.11 (stat.) \pm 0.04 (sys.)$ , for $∣ y^{ee} ∣ < 0.8$ , $p_{T}^{ee} < 0.2 GeV / c$ , and 30--80% centrality. This modulation provides evidence that the $J / ψ$ polarization is correlated with the event plane, as expected for linearly polarized photons. The observed modulation establishes polarized $J / ψ$ photoproduction as a direct probe of the transverse orientation of the initial collision geometry.
nucl-ex0 citations
06
Near-thermal state and thermodynamic response of a QCD system in ultra-central heavy-ion collisions
Yu-Shan Mu🇨🇳 · Li Yan🇨🇳 · Xu-Guang Huang🇨🇳
We present a systematic framework to extract QCD thermodynamic properties at finite baryon density from ultra-central heavy-ion collisions, where the impact parameter is nearly zero and volume fluctuations are strongly suppressed. By mapping the measured multi-particle state of each event to an effective homogeneous fireball through the conservation of total energy, total entropy and net baryon number, a near-thermal state with variations is realized from event to event, which allows thermodynamic response relations to be tested. Using STAR Beam Energy Scan data on charged particle multiplicity and net proton fluctuations, we show that the thermalization condition is satisfied within uncertainties across collision energies, validating the interpretation of ultra-central events as small deviations from a thermally equilibrated state. We then generalize the response relations to finite baryon chemical potential, expressing the response coefficients in terms of the speed of sound and susceptibilities. Our results provide a baseline for using ultra-central collisions to probe the QCD equation of state and phase structure, including the search for the critical endpoint.
↳ nucl-thhep-phnucl-ex0 citations
07
Information-Loss Location Estimation and Curvature-Scale Analysis of Physical Measurements: A Gaussian, Cauchy, and Logistic Neutron-Lifetime Benchmark
Victor V. Golovko
We develop and implement a two-step location-scale analysis for repeated physical measurements when the underlying distribution is not known. For a chosen substitute distribution, stationarity of population Kullback-Leibler information loss at fixed scale motivates the location score, which we apply to the observed measurements through empirical cross-entropy. Steiner's curvature rule then defines a companion scale separately. We place Gaussian, Cauchy, and logistic substitutes in one common construction and implement them reproducibly on a physics benchmark. For the logistic substitute, we pair the established bounded location score with a scale defined by the curvature rule rather than by a fitted tuning constant or a scale-likelihood equation. For Gaussian measurements with different quoted uncertainties, an experiment-level curvature convention and a stated variance mapping give an exact algebraic connection to a standard residual-based variance estimate for a weighted fit. Applied to a published 21-measurement neutron-lifetime compilation, the inverse-variance weighted, most frequent value, and logistic locations are 878.689, 881.164, and 882.835 s, respectively. These values are benchmark results of the compared constructions and are not proposed as a new recommended neutron lifetime.
↳ physics.data-annucl-ex0 citations
08
Inclusive Neutral-Kaon Photoproduction on the Deuteron
Mutoharoh · Agus Salam · Terry Mart🇮🇩
We report on our study of inclusive neutral-kaon photoproduction on the deuteron, $d (γ, K^{0}) Y N$ , for photon energies between 0.9 and 1.1 GeV. The calculation is performed in the impulse approximation, with the deuteron wave function generated from the Bonn One-Boson-Exchange-Potential in $q$ -space (OBEPQ) within a non-relativistic framework, while the kinematics and the elementary operator are kept relativistic. For the elementary operator we employ a recently developed isobar model that includes high-spin nucleon and $Δ$ resonances and has been constrained by nearly 20,000 data points, and we compare its predictions systematically with those of the Kaon-Maid model. For the first time, the NKS1 and NKS2 data are subjected to a quantitative analysis within a modern elementary production framework. The New Operator provides a considerably better description of the data, whereas Kaon-Maid overestimates the measured cross section by up to a factor of four at the higher photon energies, a discrepancy that can be traced back to its unconstrained $γ n \to K^{0} Λ$ amplitude. We further show that the finite photon-energy and kaon-angle bins of the existing measurements generate a theoretical uncertainty comparable to the difference between the two models, so that a proper comparison with the data requires the calculation to be averaged over the experimental acceptance. A three-dimensional mapping of the cross section over the kaon momentum and angle reveals a narrow quasi-free ridge, accompanied by a second structure associated with the opening of the $Σ$ channels, from which we identify the kinematics most favorable for future measurements. Finally, the tensor target asymmetries are found to be far less sensitive to the elementary operator than the cross section, and therefore probe the nuclear dynamics in a way that is complementary to the cross section.
↳ nucl-thhep-phnucl-ex0 citations
09
Precision Sum Rule for Nucleon Isovector Polarizabilities and the Proton-Neutron Mass Difference
Xiong-Hui Cao🇨🇳 · Ling-Yun Dai🇨🇳 · Feng-Kun Guo🇨🇳
The precision of the electromagnetic proton-neutron mass difference $δ m_{QED}$ extracted from the Cottingham formula hinges on a subtraction function whose low-energy normalization $S ˉ (0)$ is fixed by the isovector combination of the proton and neutron polarizabilities, $(α_{E 1} - β_{M 1})^{p - n}$ . We derive a dispersive sum rule for this combination in terms of $s$ -channel photoabsorption cross sections and the product of $t$ -channel $γ γ \to π η / K K ˉ_{I_{t} = 1}$ and $π η / K K ˉ_{I_{t} = 1} \to N N ˉ$ amplitudes, without invoking Reggeon dominance. Combining empirical pion-photoproduction multipoles with coupled-channel Muskhelishvili--Omnès representations of the scalar-isovector $π η / K K ˉ$ amplitudes, we obtain $(α_{E 1} - β_{M 1})^{p - n} = - 2.26 (73) \times 1 0^{- 4} fm^{3}$ , fixing its sign and reducing the uncertainty by a factor of 4 compared with the previously known value. This result yields $S ˉ (0) = - 1.76 (61) GeV^{- 2}$ , leading to $δ m_{QED} = 0.7 1_{- 0.06}^{+ 0.03} MeV$ , substantially more precise than previous Cottingham determinations. The negative $S ˉ (0)$ also provides a stringent low-energy test of Reggeon dominance in the subtraction function.
↳ hep-phhep-latnucl-exnucl-th0 citations
10
Rotational effects on the chiral crossover transition in QCD matter
Nandita Padhan🇮🇳 · Kshitish Kumar Pradhan🇮🇳 · Arghya Chatterjee🇮🇳 · Raghunath Sahoo🇮🇳
We analyze the impact of rotation on the chiral crossover transition of QCD matter within the framework of a hadron resonance gas model. By extending the conventional formulation of the renormalized chiral condensate to a rotating hadronic medium, we find that rotation significantly modifies the chiral condensate and systematically suppresses the pseudocritical temperature as the angular velocity increases. The pseudocritical line in the $T - ω$ plane is examined, and the rotational dependence of the pseudocritical temperature is quantified through leading- and next-to-leading-order rotational curvature coefficients. We further investigate the combined effects of angular velocity and baryon chemical potential and find that their interplay leads to a stronger suppression of the pseudocritical temperature. Additionally, the spatial dependence of the chiral crossover transition is examined through the radial variation of the pseudocritical temperature. We find that the pseudocritical temperature decreases with increasing radial distance, indicating that the chiral crossover sets in at progressively lower temperatures as one goes away from the rotation axis.
↳ hep-phhep-exhep-thnucl-ex+10 citations

Affiliations

first authorsco-authorsvia INSPIRE