Nuclear Experiment·nucl-ex

Wed·Aug 5, 2026Wednesday·August 5, 2026

6 papers—4 primary·2 cross-listed

01
Elliptic flow of $π^{0}$ mesons in Cu $+$ Au collisions at $s_{_{N N}} = 200$ GeV and U $+$ U at $s_{_{N N}} = 193$ GeV
PHENIX Collaboration: N.J. Abdulameer🇭🇺 · U. Acharya🇺🇸 · C. Aidala🇺🇸 · N.N. Ajitanand🇺🇸 · Y. Akiba🇯🇵 · R. Akimoto🇯🇵 · J. Alexander🇺🇸 · D. Anderson🇺🇸 · S. Antsupov🇷🇺 · K. Aoki🇯🇵 · N. Apadula🇺🇸 · H. Asano🇯🇵 and 371 other authors
The second-order azimuthal anisotropy coefficients ( $v_{2}$ ) of neutral $π$ mesons ( $π^{0}$ ) have been measured as a function of the transverse momentum ( $p_{T}$ ) and centrality of Cu $+$ Au collisions at $s_{_{N N}} = 200$ ~GeV and U $+$ U at $s_{_{N N}} = 193$ GeV at the Relativistic Heavy Ion Collider. The analysis used experimental data collected by the PHENIX experiment at midrapidity $∣ η ∣ < 0.35$ over a broad $p_{T}$ range up to $\approx 10$ ~GeV/ $c$ , and the obtained results are compared with previous PHENIX measurements in Au $+$ Au collisions at $s_{_{N N}} = 200$ ~GeV. In all three collision systems, the $π^{0}$ ~ $v_{2}$ values follow the scaling with the second-order participant eccentricity and the cube root of the number of participating nucleons ( $ε_{2} N_{part}^{1/3}$ ) up to $\approx 4$ ~GeV/ $c$ . Furthermore, the behavior of the azimuthal-dependent $π^{0}$ nuclear-modification factors and associated fractional parton-energy losses are evaluated from measured nonzero $v_{2}$ values of $π^{0}$ at $p_{T} > 5$ GeV/ $c$ and found to be approximately the same for similar values of $N_{part}^{1/3}$ in these collision systems. These findings demonstrate that the mechanism of $π^{0}$ $v_{2}$ generation exhibits a high degree of universality across different initial geometries of heavy-ion collisions.
nucl-ex0 citations
02
Strangeness production in light-ion collisions with ALICE at the LHC
Sara Pucillo for the ALICE Collaboration🇮🇹
Measurements in pp and p--A collisions have revealed that small collision systems exhibit most of the signs traditionally attributed to heavy-ion collisions, such as the smooth increase of the strange hadron yields with the collision multiplicity (strangeness enhancement). A key question is how these effects evolve with system size and whether they can be described within a unified framework. The recently collected oxygen--oxygen (OO) collision data by ALICE at $s$ = 5.36 TeV provide an unprecedented opportunity to explore an intermediate-size system that naturally bridges the gap between pp and Pb--Pb collisions. In this contribution, we present the first results on the production of (multi-)strange particles as a function of charged-particle multiplicity in OO collisions. This allows us to investigate strangeness enhancement across different system sizes at comparable multiplicities, providing new insights into the mechanisms of strangeness production. The experimental results are compared with model predictions from various Monte Carlo generators.
nucl-exhep-ex0 citations
03
Measurement of forward jet suppression in Pb+Pb collisions at $s_{NN} = 5.02$ $ TeV with the ATLAS detector
ATLAS Collaboration
Inclusive jet production is measured with the ATLAS detector at the LHC at $s_{NN} = 5.02$ TeV in Pb+Pb and $pp$ collisions, using data samples corresponding to integrated luminosities of 1.72 nb $^{- 1}$ and 255 pb $^{- 1}$ , respectively. The jet nuclear modification factor, $R_{AA}$ , is reported for anti- $k_{t}$ jets with radius parameter $R = 0.4$ in the forward-rapidity intervals $2.8 < ∣ y ∣ < 3.2$ and $3.2 < ∣ y ∣ < 3.6$ , probing transverse momenta $p_{T} > 74$ GeV. The observed $R_{AA}$ values show a significant suppression of jet yields in Pb+Pb collisions relative to those measured in $pp$ collisions. The suppression increases monotonically from peripheral to central collisions and exhibits a mild jet $p_{T}$ dependence. A comparison with previous ATLAS measurements indicates stronger jet suppression in the $2.8 < ∣ y ∣ < 3.2$ region than in the $∣ y ∣ < 2.8$ region. In the $3.2 < ∣ y ∣ < 3.6$ region, the precision of the measurement does not allow a conclusive comparison with the $∣ y ∣ < 2.8$ region. These results constitute the first measurement of inclusive jet suppression at forward rapidity in heavy-ion collisions and provide new constraints on flavor, geometric, and medium-density dependence of parton energy loss.
nucl-exhep-ex0 citations
04
Statistical and non-statistical $γ$ -decay properties of $^{64}$ Zn
A. C. Larsen🇳🇴 · M. Guttormsen🇳🇴 · T. K. Eriksen🇳🇴 · G. M. Tveten · H. Utsunomiya · J. K. Dahl · N. Shimizu🇯🇵 · T. Ari-izumi · F. L. Bello Garrote · L. T. Bell🇳🇴 · M. M. Bjørøen · F. W. Furmyr and 14 other authors
We present a study on the $γ$ -decay properties of $^{64}$ Zn using the Oslo method on $^{64}$ Zn( $p, p^{'} γ$ ) data combined with $^{64}$ Zn $(γ, n)$ cross-section measurements at the NewSUBARU facility. With the Oslo method, we have measured the $γ$ -ray strength function ( $γ$ SF) and the nuclear level density (NLD) below the neutron threshold. We observe that the NLD trend in the quasi-continuum region of $^{64}$ Zn is best characterized by a constant-temperature-like model. %with temperature parameter $T_{CT} = 1.21 (5)$ MeV. Surprisingly, we find that $γ$ -ray transitions from the quasi-continuum decaying directly to the $0^{+}$ ground state seem to be strongly hindered with a hindrance factor of $κ \approx 0.5$ , which could be an indication of non-statistical effects in the ground-state decay due to, \textit{e.g.}, differences in nuclear shapes. For $γ$ energies above the neutron separation energy, the NewSUBARU ( $γ, n$ ) data set probes a significant part of the giant dipole resonance. Furthermore, we find that the Oslo-method $γ$ SF shows a rather smooth behavior, with a clear low-energy enhancement (LEE) for $E_{γ} < 4$ MeV.
nucl-exnucl-th0 citations
05
On the nature of fully-charmed four-quark exotic state $X (6900)$ from its photoproduction off nuclei
E. Ya. Paryev🇷🇺
The possibility to study the nature of fully-charmed tetraquark state $X (6900)$ from its inclusive photoproduction off nuclei near the kinematic threshold is investigated within the collision model based on the nuclear spectral function. The model accounts for $X (6900)$ production in direct photon--nucleon interactions as well as three different scenarios for its internal structure: compact tetraquark, molecule of the two hidden-charm $J / ψ$ and $ψ (3770)$ mesons and the mixture of both of them. We calculate within these scenarios the absolute and relative excitation functions on $^{12}$ C and $^{184}$ W nuclei at near-threshold photon energies of 30--40 GeV, the absolute momentum differential cross sections and ratios of them for the $X (6900)$ meson production off these target nuclei at laboratory polar angles of 0 $^{\circ}$ --5 $^{\circ}$ and for photon energy of 35 GeV as well as the A-dependences of its transparency ratios at photon energy of 35 GeV. We show that these observables reveal a definite sensitivity to the $X (6900)$ intrinsic structure. Therefore, they might be useful for the determination of this structure from the comparison of them with the experimental data from the future experiments at the upcoming experimental facilities, such as the planned electron-ion colliders in the United States and China.
↳ hep-phhep-exnucl-exnucl-th1 citation
06
Finite-spectrum Lorentz integral transform calculation of the $^{4}$ He photoabsorption cross section in the no-core shell model
P. Yin · H. T. Zhao · C. Y. Zhai🇨🇳 · J. P. Vary🇺🇸 · H. Li🇨🇳 · J. M. Dong · H. J. Ong🇨🇳 · X. Zhao · P. J. Fasano🇺🇸 · A. M. Shirokov🇷🇺 · J. Chen🇺🇸 · D. Y. Tao · B. Zhou🇨🇳 · C. Ji🇨🇳
We develop and validate a finite-spectrum implementation of the Lorentz integral transform (LIT) within the \textit{ab initio} no-core shell model (NCSM) for calculating the photoabsorption cross section of $^{4}$ He. A large set of $1^{-}$ eigenstates is explicitly calculated in the NCSM, and the LIT is constructed from their excitation energies and the corresponding $E 1$ transition strengths. This finite-spectrum approach is complementary to conventional inhomogeneous-equation and Lanczos-based implementations of the LIT method for photoabsorption cross sections. Using the Daejeon16 interaction, we extract the photoabsorption cross section and examine its stability with respect to the model-space truncation, excitation-energy cutoff, and LIT parameters. The reliability of the finite-spectrum extraction is assessed by comparing the $E 1$ polarizability and bremsstrahlung sum rule obtained from the discrete NCSM spectrum with the same quantities obtained by integrating the extracted cross section. The extracted cross section captures the principal features of the available $^{4}$ He photonuclear data in the giant-dipole-resonance region and is consistent, in the low-energy rise and main-peak region, with earlier chiral-interaction NCSM-LIT results obtained from Lanczos-based evaluations, while the present calculation with the Daejeon16 interaction exhibits a more pronounced high-energy shoulder. The present work provides a controlled finite-spectrum NCSM-LIT route from explicitly calculated many-body eigenstates and transition strengths to photoabsorption cross sections.
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Affiliations

first authorsco-authorsvia INSPIRE

Elliptic flow of π0 mesons in Cu+Au collisions at sNN​​​=200 GeV and U+U at sNN​​​=193 GeV

Strangeness production in light-ion collisions with ALICE at the LHC

Measurement of forward jet suppression in Pb+Pb collisions at sNN​​=5.02$ TeV with the ATLAS detector

Statistical and non-statistical γ-decay properties of 64Zn

On the nature of fully-charmed four-quark exotic state X(6900) from its photoproduction off nuclei

Finite-spectrum Lorentz integral transform calculation of the 4He photoabsorption cross section in the no-core shell model

Affiliations

Elliptic flow of $π^{0}$ mesons in Cu $+$ Au collisions at $s_{_{N N}} = 200$ GeV and U $+$ U at $s_{_{N N}} = 193$ GeV

Measurement of forward jet suppression in Pb+Pb collisions at $s_{NN} = 5.02$ $ TeV with the ATLAS detector

Statistical and non-statistical $γ$ -decay properties of $^{64}$ Zn

On the nature of fully-charmed four-quark exotic state $X (6900)$ from its photoproduction off nuclei

Finite-spectrum Lorentz integral transform calculation of the $^{4}$ He photoabsorption cross section in the no-core shell model