Fundamental Problems in Subatomic Physics 2026

23 Sept 2026, 08:00 → 27 Sept 2026, 18:02 Australia/Brisbane

Novotel Cairns Oasis Resort

Anthony Thomas

The 2026 Workshop on Fundamental Problems in Subatomic Physics will be held at the Novotel Cairns Oasis Resort, Queensland, Australia, from Wednesday, September 23rd 2026 to Sunday, September 27th 2026 (Saturday and Sunday will be half days only).

Venue street address: 122 Lake Street, Cairns. (Google maps)

For those coming from overseas, please make sure to check the page regarding visa information.

 

Local Organising Committee

Anthony Thomas, Martin White, Ross Young, James Zanotti

 

International Advisory Committee

Atsushi Hosaka (RCNP, Univ. Osaka) , Makoto Oka (RIKEN), Nicole Bell (University of Melbourne), Cedric Simenel (Australian National University), Martin White (Adelaide University), Ross Young (Adelaide University)

 

 

 

FPSP 2026 gratefully acknowledges the kind support of RIKEN iTHEMS.

 

IECN Fact sheet - General visa information for participants attending Events.pdf

IECN Fact Sheet - Visa Options for Event Participants.pdf

Wednesday 23 September

08:00 → 09:00 Registration

09:00 → 09:02 Chair: Anthony Williams

09:00 → 09:30 Measuring CP violation and neutrino mixing parameters in the era of precision neutrino physics

Neutrino physics is entering an era of precision measurement, offering unprecedented opportunities to probe neutrino properties. This talk will discuss three examples. First, we present a new approach to measuring the CP-violating phase in neutrino mixing. This involves an up-down flux ratio for sub-GeV atmospheric neutrinos. For the example of Hyper-Kamiokande --- the first experiment with sufficient atmospheric-neutrino statistics in this energy range --- this approach can surpass the sensitivity of accelerator long-baseline experiments near the maximally CP-violating values $\delta = \pi/2$ and $3\pi/2$. Second, we show that DUNE can make a precise measurement of the total flux of $^8$B solar neutrinos via neutral-current interactions with argon. Combined with charged-current measurements, this would enable the most precise measurements of the solar neutrino mixing parameters using neutrino from the Sun. Finally, we discuss the ability to probe light dark matter via its annihilation to neutrinos.

Speaker: Prof. Nicole Bell (The University of Melbourne)

09:30 → 10:00 The low-energy Compton amplitude from lattice Feynman-Hellmann

Compton scattering of hadrons in the low-to-intermediate energy range provides a window into the transition between perturbative and non-perturbative QCD. However, the standard perturbative and effective theory techniques struggle to describe this energy region, making first-principles lattice calculations all the more valuable.

The CSSM/QCDSF collaboration has performed numerous calculations of the Compton amplitude using the lattice Feynman-Hellmann method. Despite the success of this approach, low-energy results remain difficult to obtain due to Feynman-Hellmann-specific contaminations.

Focusing on the structure functions $g_1$ and $F_3$, I present a method to control these low-energy contaminations and discuss physical information, such as the effective strong coupling, that can be accessed with this approach.

Speaker: Alec Hannaford Gunn (The University of Adelaide)

10:00 → 10:30 Study of a KbarNN quasi-bound state using a photon beam

The K-bar NN system is a promising candidate for studying the strongly attractive K-bar N interaction in few-body nuclear systems. We investigated the gamma d to K-zero Lambda p reaction using the LEPS2 detector at SPring-8 with tagged photon beams of 1.3 to 2.4 GeV. We observed a clear enhancement in the Lambda p invariant-mass spectrum at low momentum transfer. We performed a two-dimensional analysis of the Lambda p invariant mass and momentum transfer, including major background processes. This result provides evidence for a K-bar NN quasi-bound state.

Speaker: Ryo Kobayakawa (Osaka University)

10:30 → 11:00 Morning break

11:00 → 11:01 Chair: Ross Young

11:00 → 11:30 Resolving the muon magnetic moment mystery

For twenty years, a persistent discrepancy between experimental measurements and theoretical calculations of the muon anomalous magnetic moment has provided tantalising hints of new physics. In recent years, improvements to the experimental precision have appeared to make the tension stronger and stronger. However, at the same time, our new theoretical computation using lattice QCD overturned the theory consensus, completely eliminating the tension. I will present the latest results from the BMW and DMZ collaborations, with a determination of the hadronic vacuum polarisation contribution to a precision of 0.45%

Speaker: Finn Stokes (The University of Adelaide)

11:30 → 12:00 Nachtmann moment of the parity-violating structure function from the Feynman-Hellmann method

Precision measurements of superallowed nuclear Beta decays provide an important test of the Standard Model through the determination of Vud. Interpreting these measurements requires an accurate understanding of the effects of the strong interaction on electroweak radiative corrections at low momentum transfer. In this regime, perturbative methods are no longer applicable, motivating first-principles numerical simulations of quantum chromodynamics using lattice QCD. One quantity relevant to these radiative corrections is the first Nachtmann moment of the parity-violating structure function F3_gammaZ, which can be determined using the Feynman-Hellmann method. Our calculations are performed for the pion, providing a clean environment to investigate this approach, with future applications to nucleon calculations relevant for precision determinations of Vud.

Speaker: Mr Jordan McKee

12:00 → 12:30 Fundamental Physics at the MeV scale in Australia

We propose to build a new national facility, a Beamline Instrument for MeV-scale particle and nuclear Physics (BLIMP), to be housed at the Heavy Ion Accelerator Facility at ANU and Melbourne. BLIMP will be a Time Projection Chamber, an advanced particle detector for tracking electrons in three dimensions.

It will be capable of a broad science program encompassing searches for new particles (the X17 anomaly, Axion-Like Particles, Dark Photons) and violations of the Pauli principle with world-leading sensitivity, and globally unique nuclear physics measurements of quantum mixing in internal pair decays.

Speaker: Martin Sevior (University of Melbourne)

12:30 → 14:00 Lunch

14:00 → 14:02 Chair: Wally Melnitchouk

14:00 → 14:30 Pole-Expansion of Two-Particle Imaginary-Time Correlation Function in the Infinite Volume and Its Finite-Volume Correction

In a series of papers we have proposed and developed the idea of the pole expansion as a model-independent method to analyze the results of experiments and/or lattice QCD simulations, in particular for unstable states, that are more general than resonances.
In the talk we report on the pole expansion of the two-hadron imaginary-time correlation function in the infinite volume and its finite-volume correction.

First, in the infinite volume, by the Mittag-Leffler theorem, we express the imaginary-time correlation function as a sum of pole terms in terms of the uniformization variable, which makes the correlation function single-valued.

Secondly, in a finite volume, identifying unstable states as poles on the newly defined unphysical complex-energy sheet, we demonstrate that the finite-volume correction to the complex energy of unstable states (and the pole expansion of the correlation function) decreases exponentially as the volume size increases.

Also, we find that $(\text {imaginary time})/(\text {volume size})^2 \rightarrow 0$ is the infinite-volume limit while $(\text {imaginary time})/(\text {volume size})^2 \rightarrow \infty$ is the lowest-mode-dominant limit.
Therefore, in the former region we can obtain the pole positions and residues of unstable states by fitting the pole expansion of the imaginary-time correlation function to the results of lattice QCD simulations.

Speaker: Osamu Morimatsu (KEK)

abstract.pdf

14:30 → 15:00 Exploring non-perturbative fermion-photon interactions through the Schwinger-Dyson approach.

In order to explore key problems in particle physics such as hadron spectroscopy, confinement and dynamical mass generation, we require a non-perturbative approach to describing our particle interactions. In quantum field theory, this is tantamount to understanding the full non-perturbative structure of the fermion and photon propagators, which in turn requires knowledge of the fermion-photon vertex. Moreover, these fully determined functions would require a consistent solution at all orders of the infinite tower of Schwinger-Dyson equations, thus it is often the case that some approximation, or truncation, is required. Here, we intend to build a vertex structure that is consistent up to next-to-leading order. By introducing an ansatz into the massless fermion and photon Schwinger-Dyson equations, and demanding multiplicative renormalisability, we constrain this vertex structure at both the non-perturbative and order-by-order levels. Furthermore, we enforce a correct small-coupling limit to be in accordance with 2-loop perturbative calculations. We subsequently find a set of consistent vertex structures, as well as the next-to-leading order structures of the massless fermion and photon propagators.

Speaker: Connor Carrington (Adelaide University)

15:00 → 15:30 Lattice QCD constraints on pion electroproduction off a nucleon

Lattice QCD constraints on pion electroproduction off a nucleon

Very recently, a lattice QCD collaboration has explored threshold pion electroproduction near the physical pion mass and has simulated the relevant multipole amplitudes. Different multipole amplitudes are usually entangled in experimental data, and thus extracting each of them independently from first principles provides additional essential constraints on phenomenological theories. We use nonperturbative Hamiltonian theory to investigate the electroproduction process, providing an advanced approach with additional two-particle coupled channels to acquire the physical electric dipole amplitudes from the original lattice QCD data. We note that future lattice QCD simulations of the electric dipole amplitudes at higher energies will be much closer to their physical counterparts than the current ones near threshold. In addition, we obtain a new expression which, like that of Lellouch–L{\"u}scher, depends only on the final-state interactions but provides both the real and imaginary parts of the transition amplitudes.

Speaker: Yu Zhuge

2603.06055v1.pdf

15:30 → 16:00 Afternoon break

15:30 Chair

16:00 → 16:02 Chair: Celine Boehm

16:00 → 16:30 Dark photon in BSM new physics and dark matter searches

We present the first global QCD analysis of electron-nucleon deep-inelastic scattering and related high-energy data that incorporates the contribution of a dark photon. Our results reveal a significant reduction in $\chi^2$ relative to the baseline QCD fit, providing the first indirect hint of a dark photon's existence. Furthermore, we explore the implications of a dark photon on parity-violating electron scattering, rare kaon decays, and electroweak precision observables. Finally, we discuss the dark photon as a portal to the dark sector. Specifically, we construct a viable model featuring axial couplings between the dark photon and Dirac fermion dark matter. This scenario yields much wider regions of the dark parameter space that satisfy all existing constraints from thermal relic density, direct detection, and collider searches.

Speaker: Xuangong Wang

16:30 → 17:00 Renormalisation process for disconnected operators from Feynman-Hellmann techniques in lattice QCD

Defining a renormalisation process that incorporates mixing between connected and disconnected operators, both in the quark and gluon sectors, relies on measuring disconnected operators inserted on bare lattice quark and gluon propagators. In this talk, I will discuss calculations of these operators through Feynman-Hellmann techniques, and the results of renormalised hadronic operators when considering the full mixing matrix, in both quenched and dynamical lattice QCD simulations.

Speaker: Dr Tomas Howson (Adelaide University)

17:00 → 17:30 Perspectives on the strong CP problem

The strong CP problem arises from the apparent smallness of the QCD theta parameter, which is experimentally constrained to satisfy |theta| <~ 10^-10 despite being allowed by the local symmetries of the Standard Model. In this talk I revisit the conceptual assumptions underlying the theta-dependent formulation of QCD, with particular emphasis on the role of topology, global gauge structure, and the definition of topological charge in the continuum theory.

I discuss the distinction between local topological-density correlations, which are essential for known nonperturbative QCD phenomena such as the eta-prime mass and topological susceptibility, and the stronger assumption that the continuum functional integral must be fundamentally decomposed into globally classified smooth topological sectors. The analysis suggests that a vanishing theta parameter is consistent with a formulation of QCD based only on local gauge invariance and causal locality, while the conventional form of the strong CP problem arises after introducing additional global structure.

The implications for axion physics and nonperturbative QCD will also be briefly discussed.

Speaker: Prof. Anthony Williams (University of Adelaide)

18:00 → 19:00 Reception

Thursday 24 September

09:00 → 09:02 Chair: Finn Stokes

09:00 → 09:30 Hadron Structure from JAM Global QCD Analysis

We present recent results from the JAM Collaboration’s program to determine the one- and three-dimensional structure of the proton and other hadrons through global QCD analyses of high-energy scattering data. Recent developments include studies of the isospin dependence of the nuclear EMC effect and the stability of parton distribution functions (PDFs) at large momentum fractions, with particular attention to nuclear and power corrections. We also present the first simultaneous global analysis of transverse momentum dependent and collinear PDFs in the proton, providing a unified framework for connecting its three-dimensional and longitudinal structure. Finally, we discuss applications of generative AI to hadron structure, including pixel-based approaches to partonic imaging and the use of normalizing flows to accelerate and improve global QCD analyses of PDFs and related functions.

Speaker: Wally Melnitchouk (Jefferson Lab)

09:30 → 10:00 Overview of the Hall B physics program at JLAB

We present an overview of the active scientific program in Hall B, powered by the up to 11 GeV electron beams of the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. Hall B hosts three major collaborations, CLAS, HPS, and Prad, each operating distinct, high-precision detector systems to explore key questions in nuclear and high-energy physics. Current research spans nuclear femtography, meson and baryon spectroscopy, quark–gluon dynamics in nuclei, and searches for physics beyond the Standard Model. This talk will highlight recent experimental results and outline upcoming plans for the Hall B program.

Speaker: Stepan Stepanyan

10:00 → 10:30 Entanglement suppression for K\bar{K} scattering

The S-matrix describing the scattering process can be expressed in terms of projection operators onto the allowed spin–isospin channels and the corresponding phase shifts. Using the entanglement entropy in the spin or isospin space of the two-particle state, one can define the entanglement power, which quantifies the ability of the S-matrix to generate entanglement in the system. By investigating the conditions under which the entanglement power of the S-matrix is minimized, namely, the conditions for entanglement suppression, one can derive relations among the phase shifts in different spin-isospin channels. Furthermore, by comparing these relations with the interaction Lagrangian, one can identify the underlying symmetries [1,2].

In this work, we apply the framework of entanglement suppression to coupled-channel meson scattering involving the K\bar{K} system. We discuss the implications of the conditions obtained from entanglement suppression and the structure of near-threshold scalar resonances, such as f_0(980) and a_0(980), from the perspective of emergent symmetries.

[1] S. R. Beane, D. B. Kaplan, N. Klco and M. J. Savage, Phys. Rev. Lett. 122, 102001 (2019).
[2] I. Low and T. Mehen, Phys. Rev. D 104, 074014 (2021).
[3] T.R. Hu, K. Sone, F. K. Guo, T. Hyodo and I. Low, arXiv:2506.08960 [hep-ph].

Speaker: Katsuyoshi Sone (Tokyo Metropolitan University)

10:30 → 11:00 Morning break

11:00 → 11:02 Chair: Stepan Stepanyan

11:00 → 11:30 Connecting experimental observables in low-energy nuclear physics to the strong interaction

For much of its history, low-energy nuclear physics has been driven by phenomenological models that describe experimental observations without directly addressing their microscopic origins. Collective models based on vibrations, rotations, and shell structure have provided a remarkably successful framework for interpreting excitation spectra and other spectroscopic observables. However, rapid advances in computational power, many-body theory, and effective field theories are transforming the field. Increasingly, attempts are being made to explain nuclear structure through approaches that seek to connect emergent phenomena to the underlying nucleon-nucleon interactions and to the strong interaction.
This presentation will examine how modern studies of nuclear collectivity are contributing to this transition. Emphasis will be placed on collective quadrupole excitations, triaxiality, and shape dynamics, where traditional vibrational descriptions are increasingly being complemented by microscopic interpretations rooted in shell evolution, proton-neutron correlations, and three-nucleon forces. Recent developments, including the work of Otsuka et al. [1] on shell evolution and the emergence of triaxial collective degrees of freedom, provide a framework in which nuclear shapes and collective excitations can be understood as emergent consequences of many-body dynamics arising from the underlying nucleon interactions. In this picture, collective phenomena are no longer viewed solely as phenomenological descriptions, but as manifestations of many-body dynamics arising from nuclear forces constrained by the symmetries of QCD.

Precision measurements of electromagnetic matrix elements, transition probabilities, quadrupole moments through Coulomb-excitation observables [e.g., 2-4] provide powerful probes of the mechanisms through which collective behaviour emerges in finite nuclei. These measurements offer stringent benchmarks for modern ab initio and beyond-mean-field calculations, testing the extent to which microscopic theories can reproduce the rich spectrum of collective phenomena observed experimentally. More broadly, they highlight a fundamental shift in low-energy nuclear physics: from describing collective behaviour through phenomenological models to understanding how it emerges from nuclear interactions ultimately rooted in the strong interaction.

This work was supported in part by Australian Research Council Grant No. DP210101201 and the International Technology Center Pacific (ITC-PAC) under Contract No. FA520919PA138.

[1] T. Otsuka et al, Euro. Phys. J. A 61, 126 (2025).
[2] M. Reece et al, Phys. Rev. C 112, 034311 (2025).
[3] J. Woodside et al, Phys. Rev. C 113, 044306 (2026).
[4] T. N. Perissinotto et al, EPJ Web of Conferences 368, 00006 (2026).

Speaker: Dr AJ Mitchell (Australian National University)

11:30 → 12:00 Two-pion exchange effects in DD* potential

Motivated by the recent HAL QCD lattice results on the $D$ - $D^*$ potential at nearly physical point $m_\pi=146.4$ MeV, we theoretically examine effects from the two-pion exchange in (semi-)long-range parts of the $D$ - $D^*$ system. We employ the framework of heavy-meson chiral perturbation theory with heavy-quark spin symmetry. The pion exchanges up to next-to-next-to-leading order (N$^2$LO) are taken into account. In order to separate the (semi-)long-range contributions, we apply the dispersion-relation method to one-loop diagrams mediated by two-pion exchanges. As a result, we find that the lattice data on the $D$ - $D^*$ potential in a range of $0.5\, {\rm fm} \lesssim r\lesssim 2.0\, {\rm fm}$ is beautifully reproduced by adjusting only three higher-order couplings. In particular, it turns out that contributions from isospin-independent N$^2$LO triangle diagrams play a central role in reproducing the lattice data of the form $V_{DD^*}\sim \left({\rm e}^{-m_\pi r}/r\right)^2$ in $1.0\, {\rm fm} \lesssim r\lesssim 2.0\, {\rm fm}$. Our findings provide useful information on the (semi)long-range regime of the $D$ - $D^*$ potential focusing on two-pion exchanges.

Speaker: Daiki Suenaga (KMI, Nagoya University)

12:00 → 12:30 Effects of the gluon field in singly heavy baryons

The Quantum Chromo-Dynamics (QCD) at low energy is characterized by spontaneous breaking of chiral symmetry and color confinement. They are induced by topological vacuum configuration of the gluon filed (instanton). However, it has not yet been clarified very clearly how they work in forming hadrons. We will perform spectroscopic studies of baryon with heavy flavors, through which we could learn dynamics of quarks and gluons at low energy.
By introducing a heavy quark in a baryon, we could disentangle a relative motion of the heavy quark to the other light quark pair ($\lambda$ mode) and an internal motion of the light quark pair ($\rho$ mode). The light quark pair is expected to form a diquark correlation though the color magnetic interaction.
In this presentation, we will discuss systematics of level structure of singly heavy baryons classifying into $\lambda$/$\rho$-mode excitations. The $\lambda$-mode excitations calculated in the quark-diquark configuration indicate a so-called string tension puzzle. In the $\rho$-mode excitations, we will show an effect of instanton-induced interactions. These effects will be able to investigate at J-PARC.

Speaker: Prof. Hiroyuki Noumi (RCNP, The University of Osaka)

12:30 → 14:00 Lunch

14:00 → 14:02 Chair: James Zanotti

14:00 → 14:30 The light nuclear EMC Effect and related phenomena

Over 40 years on from the observation of the modification of nucleons in nuclei, we are still working to pin down many of the properties of the EMC Effect. Many recent efforts, both theory and experiment, have focused on testing hypotheses in light nuclei as it has become feasible to perform exact calculations on these, relatively, simpler systems. Some of the most prominent questions studied as of late relate to whether the EMC Effect is isospin dependent, isovector dependent, and if photonuclear $R=\sigma_L/\sigma_T$ is truly universal. In this talk, I will show recent work at Jefferson Lab studying these questions as well as highlight upcoming experiments that aim to provide a more complete picture of these phenomena.

Speaker: Tyler Hague (JLab)

14:30 → 15:00 Hadron spectroscopy at J-PARC with HypTPC

I will introduce our activities on hadron spectroscopy at J-PARC facility in Japan with the HypTPC detector, which is a time projection chamber with large acceptance. I will show the results of an experiment (E42, H dibaryon search) which is in the analysis phase, and introduce some other experiments which are running, or in the planning stage.

Speaker: Kiyoshi Tanida (Japan Atomic Energy Agency)

15:00 → 15:30 Feynman-Hellmann determination of $K\to\pi$ transition matrix elements

We present a lattice QCD calculation of the $K\to\pi$ transition matrix element using a flavour-changing Feynman-Hellmann approach, extending the flavour-changing formalism developed for baryons to the meson sector.
A flavour-changing temporal vector current added to the action mixes the $K$ and $\pi$ interpolating fields, and the matrix element $\langle{K}|{V_4}|{\pi}\rangle$ can be read from the induced avoided level crossing rather than from an explicit three-point function.
We develop a generalized eigenvalue analysis using pseudoscalar and temporal-axial interpolators that disentangles the forward- and backward-propagating states and extracts the resulting shifts in their energies.
We discuss the implications for $f_+(0)$ and $|V_{us}|$.

Speaker: Mischa Batelaan (Adelaide University)

15:30 → 16:00 Afternoon break

16:00 → 16:02 Chair: Ayse Kizilersu

16:00 → 16:30 Study of Electromagnetic form factor of proton based on a Parity Doublet Model

In this talk, I will show my recent analysis on the electric form factor of proton based on a parity doublet model. I first briefly review the two-parameter formula for nucleon electromagnetic form factors, and then explain how to construct the electric form factor within a parity-doublet model. The lowest-order rho-NN and omega-NN couplings are determined to reproduce the properties of nuclear matter at normal nuclear density, while higher-order couplings are determined to reproduce the electric form factor of proton.
I find that the experimental data of electric form factor are beautifully reproduced for the certain range of the chiral invariant mass. The result here suggests that electromagnetic form factors can provide constraints on the chiral invariant mass.

Speaker: Masayasu Harada (KMI, Nagoya University)

16:30 → 17:00 Extending the quark-meson-coupling model of neutron star interiors to include hidden strangeness interactions

While it is thought that hyperons should play a key role in neutron stars, hyperonic models of nuclear matter in neutron star interiors have previously led to maximum stellar masses below the observed maximum. In this research, both scalar ($\sigma^*$) and vector ($\phi$) hidden strangeness mesons are added to the quark-meson-coupling (QMC) model. QMC is unique in that the coupling directly to quarks - for instance, that of $\sigma^*$ to the s quark - naturally produces many-body interactions through the scalar polarisability, without the need for additional parameters. The strange scalar meson is incorporated into the QMC model as a new source of modification of the effective baryon mass in-medium, and the inclusion of both hidden strangeness mesons produces a stiffened equation of state, with maximum masses approaching $2.15M_{\odot}$.

Speaker: Leona James (Adelaide University)

Friday 25 September

09:00 → 09:30 Analysis of $\bar{D}^{(\ast)}\Xi^{(\ast)}_{cc}$ and $\Xi_{cc}^{(\ast)}\Xi^{(\ast)}_{cc}$ molecules as superflavor partners of $T_{cc}$

The doubly charmed tetraquark $T_{cc}$, reported by the LHCb experiment in 2022, is interpreted as a $DD^\ast$ hadronic molecular state because of its location close to the $D^{\ast +}D^0$ threshold. Motivated by this observation, we analyzed $T_{cc}$ as a $D^{(\ast)}D^{(\ast)}$ molecule using a coupled-channel approach. On the other hand, based on superflavor symmetry, which relates a heavy antiquark to a heavy diquark, the $\bar{D}^{(\ast)}\Xi_{cc}^{(\ast)}$ and $\Xi_{cc}^{(\ast)}\Xi_{cc}^{(\ast)}$ systems are expected as partner states of $T_{cc}$.

We study possible bound and resonant states of $\bar{D}^{(\ast)}\Xi_{cc}^{(\ast)}$ and $\Xi_{cc}^{(\ast)}\Xi_{cc}^{(\ast)}$ using a one-boson-exchange potential with $\pi$, $\rho$, $\omega$, and $\sigma$ exchanges. The model parameters are determined from the $T_{cc}$ system through superflavor symmetry, and the dependence on the poorly known $\sigma$-meson coupling is also investigated.

Our analysis predicts various bound and resonant states of $\bar{D}^{(\ast)}\Xi_{cc}^{(\ast)}$ and $\Xi_{cc}^{(\ast)}\Xi_{cc}^{(\ast)}$. We find that the predicted spectra depend strongly on the $\sigma$-meson coupling and that all the resonant states obtained in our analysis are Feshbach resonances. These results suggest a rich spectrum of exotic hadrons related to $T_{cc}$ and provide possible candidates for future experimental searches.

Speaker: Manato Sakai (Nagoya University)

09:00 → 09:02 Chair: Makoto Oka

09:30 → 10:00 Lattice QCD studies on the Lambda(1405) baryon in the flavor SU(3) limit

The $\Lambda(1405)$ baryon is not well described by the naive three-quark picture and has long been interpreted as a $\bar{K}N$ quasi-bound state. To study it from first principles, we compute the underlying meson-baryon interactions in lattice QCD with the HAL QCD method, in which hadron interactions are extracted as potentials. We work in the flavor SU(3) limit, where each irreducible representation becomes almost a single channel, so that the interaction can be understood in its simplest form. At a pseudo-scalar meson mass $m_M \approx 670$ MeV, we calculate the potentials in the singlet and two octet channels, in which the chiral unitary model predicts the poles corresponding to the $\Lambda(1405)$. The leading-order potentials in the derivative expansion exhibit singular behavior, which prevents a reliable extraction of observables. We therefore replace the standard local approximation by a separable potential. The separable potentials show attraction strong enough to produce bound states. In this talk, we present the resulting binding energies with their statistical and systematic uncertainties, and discuss them in the light of the mass hierarchy suggested by the chiral unitary model.

Speaker: Kotaro Murakami

10:00 → 10:30 Beyond Mean-Field Nuclear Structure for Dark Matter Direct Detection

One aspect of the search for Weakly-Interacting Massive Particle (WIMP) dark matter is direct detection, where terrestrial detectors aim to observe or constrain interactions between WIMPs and nuclei. This requires the application of a nuclear structure model in order to effectively predict the potential nuclear responses to WIMP interactions. To date, this has been achieved using the nuclear shell model. However, for heavily deformed nuclei far from stable magic numbers, mean-field models of nuclear structure are often more suitable. This approach however requires the development and application of beyond-mean-field methods of projection on nuclear angular momentum and particle number in order to account for spin-dependent nuclear responses and the effects of nucleon pairing. We present here our ongoing work in this area,having developed and applied our new methods to nuclei relevant for direct detection.

Speaker: Navneet Krishnan (Australian National University)

10:30 → 11:00 Morning break

11:00 → 11:02 Chair: Atsushi Hosaka

11:00 → 11:30 Confinement, chiral symmetry and the Bridges of Königsberg

I present some interesting speculations on quantum field theory (QFT) and its relationship to topology. A formalism is presented which relates both gauge bosons and fermions to topological objects. When viewed through the centre vortex lens, a connection can then be made with both confinement and chiral symmetry breaking.

Speaker: Prof. Chris Allton (Swansea)

11:30 → 12:00 A coupled-channel study of the nature of the $\Omega_c$ states

Recently the LHCb collaboration observed five new narrow excited states in the $\bar{K}\Xi_c$ invariant mass spectrum: the $\Omega_c(3000)$, $\Omega_c(3050)$,$\Omega_c(3065)$, $\Omega_c(3090)$ and $\Omega_c(3119)$. Following this discovery, the Belle Collaboration confirmed four of these five narrow states. A popular interpretation is that the observed $\Omega_c^*$ states correspond to the five $\lambda$-mode excited states in the conventional quark model, which are the p-wave excitations between the charm quark and the two light quarks. However, the spin assignment by the quark model does not follow the experimental data.

In this talk, we show that these new states can be explained as superpositions of meson-baryon molecular states and three-quark bare states through a systematic analysis of the low-lying $\Omega_c$ states using a coupled-channel approach [1]. Our results reproduce the mass spectrum well, and our spin assignments are consistent with the LHCb experimental analysis. We also predict one bound state below the $\bar{K}\Xi_c$ threshold, which is expected to be observed in future experiments.

[1] Y. Zhang, Q.-F. Song, Q.-F. Lü, H. Nagahiro, A. Hosaka, PRD112(2025)034035.

Speaker: Hideko Nagahiro (Nara Women's University)

12:00 → 12:30 Hadronic Exceptional Points

Exceptional points (EPs), where eigenvalues and eigenvectors coalesce, are a hallmark of non-Hermitian systems but remain largely unexplored in quantum chromodynamics (QCD). In this talk, we demonstrate that imaginary magnetic fields provide a simple realization of non-Hermitian dynamics in hadronic systems. Using both a hadronic effective Lagrangian and a constituent quark model, we identify EPs in neutral meson spectra that separate the real-spectrum and complex-eigenvalue regimes. Weak fields induce level attraction, while stronger fields lead to hadron deconfinement through an inverted confining potential. These results establish a new connection between non-Hermitian physics and QCD and provide a framework for studying relativistic bound states in non-Hermitian environments.

Speaker: Ahmad Jafar Arifi (JAEA)

12:30 → 14:00 Lunch

14:00 → 14:02 Chair: AJ Mitchell

14:00 → 14:30 Production of Polarized Antiprotons through the Production and Weak Decay of Antilambda Hyperons

Polarized antiprotons provide unique opportunities to investigate spin-dependent antiproton-proton interactions, annihilation mechanisms, and spectroscopy of hadrons. However, no practical method has yet been stablished for producing an intense polarized antiproton beam. In this work, we propose a novel method for producing polarized antiprotons through the sequential reaction $\bar{p}p\to \bar{\Lambda}\Lambda$, followed by the weak decay $\bar\Lambda \to \pi^+ \bar{p}$. In this scheme, the polarization of the daughter antiprotons originates from both the polarization of the parent antihyperons and the parity-violating nature of the weak decay.

The polarization transfer is formulated using the Lorentz-covariant polarization four-vector together with the Lee-Yang formalism [1-3] for hyperon weak decays. Monte Carlo simulations are performed using the differential cross sections and induced polarizations measured by the PS185 experiment at CERN [4] as phenomenological inputs. The momentum, angular, and polarization distributions of the secondary antiprotons are evaluated for the proposed $\pi20$ and K10 beamlines at the J-PARC Hadron Experimental Facility.

The simulation shows that the momentum and angular distributions of the daughter antiprotons closely follow those of the parent antihyperons, while being moderately broadened by the decay kinematics. The polarization consists of longitudinal self-polarization generated by parity violation and transverse components arising from spin transfer from the parent antihyperon. By selecting suitable decay kinematics in the antihyperon rest frame, antiprotons with large transverse polarization can be obtained.

The proposed method offers a realistic route to producing polarized antiprotons without requiring polarized primary beams, spin filtering, or polarized storage rings. Such a source would significantly expand future studies of spin-dependent antiproton-proton reactions, nucleon-antinucleon interactions, and hadron spectroscopy. In this presentation, the feasibility of the proposed production scheme and its expected performance at the future J-PARC secondary beamlines will be discussed.

[1] T. D. Lee and C. N. Yang, Phys. Rev. 108, 1645–1647 (1957).
[2] K. B. Luk et al. (E756 Collaboration), Phys. Rev. Lett. 85, 4860–4863 (2000).
[3] M. Huang et al. (HyperCP Collaboration), Phys. Rev. Lett. 93, 011802 (2004).
[4] P. D. Barnes et al., Phys. Rev. C 54, 1877–1886 (1996).

Speaker: Takatsugu Ishikawa (Research Center for Electron Photon Science, Tohoku University)

14:30 → 15:00 Production of high-orbital kaon excited states in the K− p reaction

In this work, a systematic investigation of the production of high-orbital-excitation kaons in $K^{-}p$ reactions is carried out within an effective Lagrangian model.
The relevant $t$-channel processes are constructed, and the model is calibrated using a single adjustable parameter determined from existing experimental data.
With this parameter, the measured production cross sections for the $K_3^*(1780)$, $K_2(1820)$, $K_2(1770)$ and $K_4^*(2045)$ states are successfully reproduced.
Employing the same framework, the production cross sections for other high-orbital kaons are predicted.
The results indicate that these states possess sizable cross sections and exhibit characteristically forward-peaked angular distributions, which is a typical feature of $t$-channel exchange, highlighting their great potential for observation in future experiments.

Speaker: Ting-Yan Li (Lanzhou University)

2606.15736v2.pdf

15:00 → 15:30 Omega baryon excited state contaminations using Heavy Baryon Chiral Perturbation Theory (HBChPT)

To achieve the high precision required for theoretical inputs into quantities such as muon g-2 and CKM matrix elements, lattice QCD calculations require a precise determination of the lattice scale. This requires a quantity that is measured experimentally to very high precision and match a lattice calculation onto the experimental value. One of the best choices of this quantity is the Omega baryon. To achieve the precision, systematic uncertainties, such as excited state contaminations to the ground state Omega mass, must be controlled.

In lattice calculations, the mass of the Omega baryon can be extracted using 2-point correlators. However, there are two issues: at large times, there is noise that grows exponentially; and at short times, there are higher energy states present. Using chiral perturbation theory methods with a heavy baryon Lagrangian, the excited state contamination of the Omega baryon can be quantified to understand the multiparticle state contributions on the ground state Omega mass. I will present a comparison on how well HBChPT relates to lattice QCD determination of the Omega mass from the Budapest–Marseille–Wuppertal collaboration using GEVP methods.

Speaker: Isabella Frankel

15:30 → 16:00 Afternoon break

16:00 → 16:02 Chair: Martin Sevior

16:00 → 16:30 J/psi interaction from the two-pion decays of psi(2S)

This is an attempt to extract J/psi-N interaction from the decay of psi(2S) via two pion emission. The diagonal matrix element of the 2-pion source J/psi to J/psi is related to the transition matrix element of psi(2S) to J/psi which can be extracted by the known experimental data. A naive estimate implies that there is non-negligible strength for the J/psi-2pion coupling, which would provide a hint to resolve the discrepancy in the J/pi-N interaction; very small strength from the J/psi photoproduction and some finite strength from the HAL lattice simulation.

Speaker: Atsushi Hosaka

16:30 → 17:00 Structure of the Omega-(2012) with Hamiltonian Effective Field Theory

Structure of the $\Omega^{-}(2012)$ with Hamiltonian Effective Field Theory

We investigate the internal structure of the $\Omega(2012)^-$ by analyzing lattice QCD simulation and experimental data within Hamiltonian effective field theory, considering both $J^P = 1/2^-$ and $3/2^-$ assignments. The couplings to the dominant decay channel $\Xi \bar{K}$ and the near-threshold channel $\Xi(1530) \bar{K}$ are determined through the quark-pair-creation model. By studying the lattice QCD spectra in these two spin-parity scenarios, we extract the masses and widths of the resonances. We notice that the $J^P = 3/2^-$ resonance is consistent with the observed $\Omega(2012)^-$ while the recently reported $\Omega(2109)^-$ may be a $J^P = 1/2^-$ $\Omega$.

Speaker: Fang-Chao Han (Lanzhou University)

xdbd-v5hb.pdf

18:30 → 21:30 Dinner

Saturday 26 September

09:00 → 09:02 Chair: Chris Allton

09:00 → 09:30 Long-range neutrino-mediated forces in precision atomic parity violation

Precision measurements of atomic parity violation and parity-violating electron scattering provide sensitive tests of the Standard Model at low energies. In this work, we show that exchange of two neutrinos, together with analogous fermion-loop contributions, generates a parity-violating dispersion interaction between atomic electrons and quarks. Although the long-range potential scales as $G_F^2/r^5$, its singular short-distance behaviour produces a finite correction of order $G_F^2M_Z^2\sim \alpha G_F$, comparable to conventional electroweak radiative corrections.

We calculate the resulting modification of nuclear weak charges and show that loops of neutrinos, charged leptons, and quarks lighter than the $Z$ boson give a significant enhancement. For medium and heavy atoms the correction is approximately −0.8%. In cesium, this shift is larger than the present experimental uncertainty and brings the Standard Model prediction for the parity-violating amplitude into agreement with experiment. The same mechanism also produces a few-percent correction to the proton weak charge, relevant for parity-violating electron–proton scattering.

These results show that neutrino-mediated dispersion parity violation is an important Standard Model effect for interpreting precision weak-charge measurements and for constraining possible new physics.

Speaker: Igor Samsonov (UNSW)

09:30 → 10:00 Nonperturbative Hamiltonian Framework for General N-Body Finite-Volume Systems: three‑ and four‑particle spectra

Extracting resonance properties from lattice QCD increasingly requires a finite-volume framework capable of treating coupled multi-particle dynamics beyond two-body systems. Here we develop a nonperturbative Hamiltonian framework(NPHF) for general $N$-body finite-volume systems, establishing a direct connection between finite-volume spectra and infinite-volume scattering observables. The framework incorporates lattice and isospin symmetries and provides a unified treatment of coupled channels with different particle numbers in the finite volume. We implement the NPHF in an open-source numerical package and apply it to the $\omega$-meson system, where the $3\pi$ dynamics are treated nonperturbatively and the $\omega$ pole is extracted from the real lattice QCD spectra. Using a controlled four‑particle benchmark built upon the $\sigma-2\pi-4\pi$ model, we validate our framework for few-body finite‑volume problems. This constitutes the first demonstration of finite‑volume calculations incorporating genuine four‑particle sectors. Our work establishes the NPHF as a powerful tool for investigating multi‑hadron resonances and coupled‑channel dynamics from lattice QCD.

Speaker: kang yu (University of Chinese Academy of Sciences)

10:00 → 10:30 Resonance Structure with Generalised Parton Distributions in Deeply Virtual Compton Scattering with Pion Emission

Generalised parton distributions (GPDs) provide a three-dimensional description of hadron structure and offer a framework for investigating the internal structure of nucleon resonances. We study deeply virtual Compton scattering with an associated pion in the final state, $eN\rightarrow e\gamma N\pi$, where the $N\pi$ system provides access to both conventional nucleon GPDs and nucleon-to-resonance transition GPDs.

A phenomenological description of this process is developed including deeply virtual Compton scattering, Bethe–Heitler production, and their interference. Both diagonal mechanisms and direct transitions to the $P_{11}(1440)$ Roper and $S_{11}(1535)$ resonances are considered. The diagonal amplitude is projected onto the corresponding $N\pi$ partial waves, allowing a consistent comparison with the resonant contributions. Final-state interactions are incorporated through phase-shift and coupled-channel $K$-matrix treatments.

Numerical results at JLab-like kinematics demonstrate the relative importance of the two mechanisms and show that final-state interactions can substantially modify the extracted resonance-region observables. Implications for accessing transition GPDs in future measurements are discussed.

Speaker: Matthew Rumley (Adelaide University)

10:30 → 11:00 Morning break

11:00 → 11:02 Chair: Tyler Hague

11:00 → 11:30 The phi meson in nuclear matter from theory and experiment

It is currently still not established how the phi meson mass and decay width behave in a dense
environment such as nuclear matter. In this talk, the status of recent theoretical research related
to the properties of the phi meson in nuclear matter is reviewed, with a focus on observables
measured at the KEK E325, J-PARC E16 and E88 experiments, including dilepton and K+K-
decay modes and their angular distributions. The relation of these observables to fundamental
properties of nuclear matter, such as chiral symmetry, its partial restoration, in-medium Lorentz
symmetry violation and the resultant modification of its dispersion relation, will be discussed.
Recent results of a collaboration between theorists and experimentalists, with the goal of
simulating proton-nucleus reactions to produce phi mesons in nuclei, will also be presented.

Speaker: Philipp Gubler (JAEA)

11:30 → 12:00 Hadronic molecular states of heavy meson-nucleon systems

In recent years, there has been growing interest in exotic hadrons that exhibit structures beyond the conventional hadron picture, where baryons are treated as three-quark states ($qqq$) and mesons as quark-antiquark ones ($q\bar{q}$). In the charm sector, many exotic hadrons such as $XYZ$, $P_c$, and $T_{cc}$ have been reported in experiments. Most of these states have appeared near hadron thresholds and hence have been considered as hadronic molecular states. Although the hadron-hadron interactions are responsible for binding constituent hadrons, they are not yet fully understood. Understanding hadronic interactions is essential for uncovering the dynamics of low-energy QCD.

In this talk, we discuss hadronic molecules including heavy mesons (such as $\bar{D}$ or $B$ mesons), focusing on their bound and resonant states. Heavy mesons are expected to be constituents of many hadronic molecular states, and thus understanding their interactions is very important to investigate the exotic hadrons. In the heavy hadron sector, the heavy quark symmetry is a key ingredient, which induces channel coupling effects and also predicts spin partner states. We study properties of hadronic molecules of a heavy meson and a nucleon within the meson exchange model.

Speaker: Prof. Yasuhiro Yamaguchi (Tokyo Metropolitan University)

12:00 → 12:30 Topological data analysis of center vortices in dynamical lattice QCD

Center vortices play a fundamental role in our understanding of the QCD vacuum, the mechanism of quark confinement, and dynamical chiral symmetry breaking. They are topological defects that form closed two-dimensional sheets that organise into highly intricate, foam-like structures. In this work, we use topological data analysis to study the structure of center vortices in dynamical lattice QCD. In particular, we use Betti numbers to study vortex sheet “percolation" and to characterise the size of its topological features and its embedding in spacetime. We focus on the geometric and topological changes that occur with temperature, particularly across two key temperatures, specifically the chiral temperature $T_c$ and the proposed deconfinement temperature $T_d$.  We find that there are three distinct regimes: below $T_c$, between $T_c$ and $T_d$, and above $T_d$, where the geometry and topology exhibit qualitatively different behaviour.

Speaker: Thakur Giriraj Hiranandani (the University of Queensland)

12:30 → 13:30 Lunch

Sunday 27 September

09:00 → 09:02 Chair: Nicole Bell

09:00 → 09:30 The SABRE South Experiment at the Stawell Underground Physics Laboratory

SABRE is an international collaboration that will operate similar particle detectors in the Northern (SABRE North) and Southern Hemispheres (SABRE South). This innovative approach aims to distinguish potential dark matter signals from seasonal backgrounds: a pioneering strategy only feasible with a Southern Hemisphere experiment. SABRE South is located at the Stawell Underground Physics Laboratory (SUPL), in regional Victoria, Australia. SUPL is a newly constructed facility situated 1024 metres underground (∼2900 metres water equivalent) within the Stawell Gold Mine. Its construction was completed in 2023.

SABRE South employs ultra-high purity NaI(Tl) crystals immersed in a linear alkyl benzene (LAB)-based liquid scintillator veto, surrounded by passive steel and polyethylene shielding, and topped with a plastic scintillator muon veto. Significant progress has been made in the procurement, testing, and preparation of equipment for the installation of SABRE South. The assembly of the experiment at SUPL will take place this year. The SABRE South muon detector and data acquisition systems are already operational and actively collecting data at SUPL, and full commissioning of SABRE South is planned this year. This presentation will provide an update on the overall progress of the SABRE South construction, its anticipated performance, and its potential physics reach.

Speaker: Anthony Williams

09:30 → 10:00 Experimental studies for hyperon bound systems at the J-PARC K1.8 beam line

At the J-PARC K1.8 beamline, experiments were performed and planned to study hyperon-bound systems such as Lambda and Xi hypernuclei and Xi atoms, using several techniques. These measurements, including hyperon scattering experiments, provide knowledge of hyperon-nucleon and hyperon-hyperon interactions. Recent results and plans for experiments at the beam line will be presented in this contribution.

Speaker: Takeshi O. Yamamoto (JAEA)

10:00 → 10:30 Neutron stars have long been used to gain insights into the nuclear equation of state (EoS)

Neutron stars have long been used to gain insights into the nuclear equation of state (EoS). Here, we introduce short-distance repulsive interactions within the framework of the quark-meson coupling (QMC) model and show that the EoS supports heavy 2.1 solar mass stars even in the presence of hyperons and an exotic six-quark H-dibaryon. I close by discussing neutrino transport and stellar f-mode oscillations as possible probes to distinguish between nucleonic and non-nucleonic degrees of freedom, which the mass-radius measurements alone cannot resolve.

Speaker: Mr Jesper Leong (Adelaide University)

10:30 → 11:00 Morning break

11:00 → 11:02 Chair: Derek Leinweber

11:00 → 11:30 Nuclear Gravitational Form Factor

Gravitational form factors of atomic nuclei ranging from 16O to 208Pb are calculated by the use of the realistic relativistic mean field (RMF) picture of nuclei. The D term, which corresponds to the radial distribution of the shear force density (traceless part of the stress tensor), is of particular interest. It shows a strong mass number dependence and also shell structure of nuclei.

Speaker: Makoto Oka

11:30 → 12:00 Nuclear structure starting at the quark level

One challenging aspect of the modern study of atomic nuclei is to understand how they emerge from QCD. After reviewing the development of the quark meson coupling model, we show that it does indeed provide a quantitative theory of nuclear structure starting at the quark level. We then present some of the latest results obtained with the model, from superheavy nuclei to the potential interaction with a particular form of dark matter.

Speaker: Anthony Thomas

12:00 → 13:00 Lunch