In-medium generator coordinate method for nuclear collective excitations and double-beta decays Room: Panasonic Hall

Investigation of the Coulomb interaction in finite nuclei

• Kenta Hagihara (University of Tsukuba)

Room: Panasonic Hall The ground-state properties of nuclei can be described within the liquid-drop model, where nuclear stability against deformation is governed by the competition between the surface energy and the Coulomb energy. The Coulomb interaction also plays an essential role in spontaneous fission. Motivated by these considerations, we focus on nuclear deformation and Coulomb effects in finite nuclei. To quantify Coulomb contributions to nuclear structure, we perform systematic calculations of even–even nuclei within nuclear density functional theory. We then examine how Coulomb effects manifest in microscopic observables, with particular emphasis on the evolution of canonical single-particle energies as visualized in Nilsson diagrams.

A FewTopics in Nuclear Deformation and High-energy Physics

• Masakiyo Kitazawa (YITP, Kyoto University)

Room: Panasonic Hall

Benchmarking nuclear matrix elements of 0νββ decay with high-energy nuclear collisions

• Xin Zhang

Room: Panasonic Hall Reducing uncertainties in the nuclear matrix element (NME) remains a critical challenge in designing and interpreting experiments aimed at discovering neutrinoless double beta (0νββ) decay. Here, we identify a class of observables, distinct from those employed in low-energy nuclear structure applications, that are strongly correlated with the NME: momentum correlations among hadrons produced in high-energy nuclear collisions. Focusing on the 150Nd→150Sm transition, we combine a Bayesian analysis of the structure of 150Nd with simulations of high-energy 150Nd+150Nd collisions. We reveal prominent correlations between the NME and features of the quark-gluon plasma (QGP) formed in these processes, such as spatial gradients and anisotropies, which are accessible via collective flow measurements. Our findings demonstrate collider experiments involving 0νββ decay candidates as a platform for benchmarking theoretical predictions of the NME.

From heavy-ion to small systems and forward region: Effects from early stage dynamics

• Shujun Zhao (Sophia university)

Room: Panasonic Hall

Tip–Tip Collisions of Deformed Nuclei as a Probe of the High-Density Equation of State

• Chiho Nonaka (Hiroshima University / Nagoya University)

Room: Panasonic Hall We explore the equation of state (EOS) of dense nuclear matter using central collisions of deformed nuclei, focusing on tip–tip collisions. In collisions of strongly deformed nuclei such as Er, geometric asymmetry remains even in central events, resulting in a finite elliptic flow. Because flow observables are sensitive to the EOS, selecting specific collision geometries can provide information on the high-density EOS. In addition, tip–tip central collisions avoid the spectator-shadowing effect that often obscures particle emission from the high-density region in low-energy nuclear collisions. First, we analyze high-energy nuclear collisions, where lattice-QCD-based EOSs are applicable, using relativistic viscous hydrodynamics. The deformation dependence of the flow coefficients in tip–tip and body–body collisions is studied to determine nuclear deformation parameters. Next, low-energy collisions are investigated using the JAM transport model. The results indicate stronger stopping and enhanced midrapidity proton production in tip–tip collisions, while characteristic differences in v1​ and v2​ reflect the EOS dependence.

RHC opportunities for clarifying nuclear shapes

• Takaharu Otsuka

Room: Panasonic Hall I will first discuss that virtually all deformed are triaxial, but this fundamental feature needs to be confrimed by many independent experiments. The RHC is one of them, and should play an important role. I will also discuss whether the RHC is a fundamentally valid approach in terms of time evolution of strongly deformed nuclei. (If you need a longer one, please let me know.)

Imprint of alpha clustering in relativistic light ion collisions

• Hadi Mehrabpour (Fudan University)

Room: Panasonic Hall

Advances in 3D modeling of the Initial State in HICs

• Oscar Garcia-Montero

Room: Panasonic Hall

Imaging nuclear structure across energy scales: from heavy to light ions

• Chunjian Zhang

Room: Panasonic Hall

Imaging two-body correlations in atomic nuclei via low- and high-energy processes

• Thomas Duguet

Room: Panasonic Hall

What does “taking a snapshot” actually mean? : similarities between subbarrier fusion and relativistic HIC

• Kouichi Hagino (Kyoto University)

Room: Panasonic Hall

Towards a microscopic description of 12C+12C fusion

• Pierre Descouvemont

Room: Panasonic Hall I present a fully microscopic description of the 12C+12C fusion reaction at stellar energies. Utilizing the multichannel Resonating Group Method (RGM), my model explicitly includes 12C+12C and alpha+20Ne reaction channels (with excited states). Results for 12C+12C elastic scattering show excellent agreement with experimental data, significantly improving the single-channel approximations. Spectroscopic analysis reveals that 24Mg states and resonances are highly mixed configurations, contradicting the concept of pure "molecular states." The calculated fusion S-factor is consistent with available experimental data and predicts both narrow and broad resonances near the Coulomb barrier. The S-factor exhibits a decrease at low energies, providing a microscopic support for the hypothesis of fusion hindrance.

A microscopic discription of carbon fusion reactions at nuclear astrophysical energy

• Kosei Nagao

Room: Panasonic Hall The 12C + 12C fusion reaction plays a key role in several astrophysical explosive phenomena. However, the cross section for the 12C + 12C fusion reaction at the relevant energy region is difficult to determine because of both experimmental limitations and strong resonant structures. We develop a reaction model that explicitly treat the C + C channel and Mg channel. The model reproduces the contrasting resonant structures and smooth energy dependences observed in the two systems. In the analysis, the experimentally observed upper limit behavior of 12C +13 C to 12C +12 C fusion cross section is employed as a practical empirical constraint.

Recent progress in nuclear lattice effective field theory

• Bingnan Lu

Room: Panasonic Hall I will give a brief review of several recent progress in the lattice Monte Carlo algorithms applied in nuclear lattice effective field theory (NLEFT), including the sign-problem-free action for heavy nuclei, second-order perturbative calculation with N$^3$LO chiral forces, renormalization group invariance of light nuclei in NLEFT, etc.

Effect of dynamical flow responses on NeNe and OO flow ratios

• Clemens Werthmann (Ghent University)

Room: Panasonic Hall In contrast to heavy ions, in ultra-central light ion collisions flow response coefficients can vary significantly. This has to be taken into account when inferring statements about the shape of the nuclei from final state flow, which can become even more difficult when the applicability of hydrodynamics is questionable. I will present and discuss results for flow responses in NeNe and OO collisions from hydrodynamics and kinetic theory.

A New ”Skin Thickness” in High-Spin Isomers as a Probe for Equation of State of Spin-polarized matter

• Toi Tachibana

Room: Panasonic Hall In T. Tachibana et al., Phys. Rev. C 112 (2025) 065806, the equation of state of spin-polarized nuclear matter was studied and the spin slope parameter of the corresponding spin-symmetry energy was discussed, which plays an important role in characterizing spin-dependent properties of nuclear systems. To explore a possible experimental probe for constraining the spin slope parameter, we investigate a new type of “skin thickness” in high-spin isomers. In analogy with the well-known linear correlation between the neutron skin thickness and the slope parameter in nuclear matter, we examine the correlation between the “spin skin thickness” of the high-spin isomer of 52Fe and the spin slope parameter. For this purpose, two possible definitions of the spin skin thickness are introduced and analyzed within the framework of the relativistic density functional theory.

Imaging atomic nuclei through high-energy nuclear collisions

• Giuliano Giacalone

Room: Panasonic Hall

On the Quantum Nature of Nuclear Deformations in Heavy-ion Collisions

• Weiyao Ke (Central China Normal University)

Room: Panasonic Hall High-energy collisions are a promising tool to study nuclear deformation, but they pose a conceptual challenge: nuclei are quantum objects whose ground state is a superposition of intrinsic deformed configurations at orientations. How does this quantum nature affect the semi-classical geometry of the Quark-Gluon Plasma fireball? I will argue that the collision does not project the nucleus onto a single orientation. Instead, it simultaneously measures the positions of many nucleons, encoding "off-diagonal" information from the collective wavefunction into the fireball's shape. I will introduce a minimal extension to the Monte Carlo Glauber model to go beyond the single-particle density and quantify this effect. Using this framework, I will estimate the impact of "orientation superposition" on the initial geometry for both light (Ne-20) and heavy nuclei. Finally, I will discuss how the manifestation of deformation differs across central collisions, ultra-peripheral collisions (UPCs), and low-energy collisions.

The neutron skin thickness from low-energy experiments

• Xavier Roca Maza

Room: Panasonic Hall In this talk I will discuss different theoretical analysis of some selected experimental data on low-energy nuclear observables --such as the dipole polarizability [1-3], the parity violating asymmetry [2-5] or the excitation energy of the Isobaric Analog State [6]-- that give access to the neutron skin thickness in medium and heavy nuclei. These measurements are complementary to the recent extraction of the neutron skin thickness using high-energy heavy ion collisions [7]. [1] http://doi.org/10.1103/PhysRevC.92.064304 [2] https://doi.org/10.1103/PhysRevLett.127.232501 [3] https://doi.org/10.1103/PhysRevLett.129.232501 [4] http://doi.org/10.1103/PhysRevLett.106.252501 [5] https://doi.org/10.1103/PhysRevLett.134.192501 [6] https://doi.org/10.1103/PhysRevLett.120.202501 [7] https://doi.org/10.1103/PhysRevLett.131.202302

Fission in ultraperipheral heavy-ion collisions

• Ramona Vogt

Room: Panasonic Hall

TBA

• Pengwei Zhao

Room: Panasonic Hall

Future Ion Collisions at the LHC: challenges and opportunities

• Reyes Alemany Fernandez (CERN)

Room: Panasonic Hall In recent years, interest in conducting experiments with lighter ions than lead at the CERN Accelerator Complex has grown significantly within the ion-physics community. Collisions such as Xe‑Xe, O‑O, Ne‑Ne, and p‑O have already been delivered to the LHC. Comparisons across these systems offer a unique opportunity to probe nuclear‑geometry‑driven hydrodynamic flow in light‑ion systems at LHC energies. The potential for delivering new ion species to the LHC during Run 4 (2030–2033) and beyond is currently under active study. Complementing the LHC program, the NA61/SHINE fixed‑target experiment at the SPS has requested B, O, and Mg collisions during Run 4 to investigate the quark–gluon plasma near the critical point. In parallel, the proposed HEARTS++ facility—a radiation‑to‑electronics test area for Run 4 and beyond—aims to enable fast switching among five ion species (O, Ar, Kr, Xe, and Pb), with each transition achievable within 15 minutes. Consolidating these future scenarios calls for a comprehensive evaluation of the present injector complex’s performance with light ions. This contribution outlines the current operational challenges for light‑ion beams and presents a proposed upgrade path for the ion complex to meet these evolving experimental needs.

TBA

• Takayuki Miyagi (University of Tsukuba)

Room: Panasonic Hall

Probing nuclear structure with heavy ion collisions

• Huichao Song

Room: Panasonic Hall

Neutron Skin from Conserved Charge Measurements at Collider Experiments

• Bjoern Schenke

Room: Panasonic Hall We propose a novel method for measuring the neutron skin of heavy nuclei using collider experiments. Specifically, we demonstrate that the neutron skin thickness of the lead nucleus can be extracted in p+Pb collisions by analyzing a double ratio: The ratio of net electric charge to net baryon number measured near the lead-going rapidity, taken for high-multiplicity events and divided by the same ratio for low-multiplicity events. We compute the expected sensitivity of the double ratio to the neutron skin within a comprehensive (3+1)D relativistic hydrodynamic framework that incorporates multiple conserved charge currents and a charge-dependent lattice-QCD-based equation of state. We provide predictions for both p+Pb collisions at √sNN = 72 GeV and √sNN = 5.02 TeV, corresponding to the center of mass energies realized in the SMOG2 fixed-target setup at LHCb and the LHC collider mode, respectively. We will also present predictions for the same observable in Pb+Pb collisions and the potential to extract the Pb neutron skin in those.

Glauber-theory calculations for medium- to high-energy nuclear scattering

• Wataru Horiuchi

Room: Panasonic Hall

Quark Mass Dependence of Nuclear Forces and its Implications for Neutron Stars

• Sanjay Reddy (University of Washington)

Room: Panasonic Hall

Nuclear Shapes Seen through Nuclear Responses

• Kenichi Yoshida (RCNP, the University of Osaka)

Room: Panasonic Hall I will discuss the effects of deformation on giant resonances and low-lying collective states.

Longitudinal flow decorrelations in Xe+Xe collisions and observables

• Koichi Murase (Research Center for Nuclear Physics, the University of Osaka)

Room: Panasonic Hall We report the current status of the simulation of the Xe+Xe collisions based on an integrated dynamical model with stochastic hydrodynamics and JAM2 and discuss the relevant observables. We also present the explicit expression of the unbiased estimator for the detector efficiency correction of an arbitrary observable, which unifies existing correction formulae for various variables, including mean pT and baryon-number cumulants, into a single explicit formula.

Imaging the structure of heavy and light nuclei at the LHC

• You Zhou (Niels Bohr Institute)

Room: Panasonic Hall

OO and Ne–Ne measurements at the LHC by ALICE collaboration

• Maxim Vitra

Room: Panasonic Hall

Probing shape transitions in finite nuclei with radioactive-ion beam spectroscopy

• Daisuke Suzuki (Department of Physics, University of Tokyo)

Room: Panasonic Hall I will report on recent and planned studies on exotic nuclear shape, and its fluctuatios and transitions in gamma-ray spectroscopy at RIBF.

Asymuthal Asymmetric Flow in Deformed Nucleus Collisions

• Shunji Nishimura (RIKEN)

Room: Panasonic Hall

TBA

• Jiangyong Jia

Room: Panasonic Hall

QGP fraction based on core-corona picture in high-energy oxygen-oxygen collisions

• Naoya Ito

Room: Panasonic Hall In high-energy nuclear collisions, numerous phenomenological analyses have been conducted regarding the Quark-Gluon Plasma (QGP) as it reaches local thermal equilibrium. In these studies, it is crucial to understand the extent to which the QGP is actually generated as a transient state of the collision. While the QGP component is dominant in large collision systems such as Pb+Pb, it remains unclear to what degree it is produced in intermediate-sized systems like O+O collisions. In this presentation, we employ the Dynamical Core-Corona Initialization (DCCI) model to systematically and quantitatively evaluate the fractions of locally equilibrated and non-equilibrated components in O+O collision reactions.