We first show how spatially all to all interaction can be induced out of the local action quantum mechanically in the presence of the disorder.Then we show that if we consider disorder in Lorentzian signature, there is a tunneling effect given by a time-non-local interaction, leading to the wormhole picture in disorder field theory. We suggest that the two point function of the random coupling play the role of the wormhole. In large N limit, for a given diagram in quenched picture with field theory wormhole, there is a corresponding unique Feynman diagram in the effective theory of the annealed avearage whose basic time-non local vertex creates entangled pair of particle sets. We call this as disorder field theory version of ER=EPR.

https://www-conf.kek.jp/kincha/

Understanding how to gauge-fix open quantum field theories is essential for building consistent open frameworks for cosmology and gravity, where gauge symmetry must coexist with dissipation and noise and decoherence. I will present our recent work developing explicit top-down constructions of open effective field theories (EFTs) for gauge degrees of freedom, with particular emphasis on the role of gauge fixing. We implement BRST quantisation on the Schwinger-Keldysh contour and show that the in-in boundary conditions reduce the doubled global BRST symmetry to a single diagonal copy. This diagonal BRST symmetry is nevertheless sufficient to guarantee that the influence functional remains gauge invariant under two independent gauge transformations, retarded and advanced, independently of the choice of initial state, the presence of symmetry breaking phases, and whether the gauge theory is Abelian or non-Abelian. I will also remark that once a consistent quantisation scheme is chosen, the Schwinger-Keldysh path integral is uniquely determined, and with it the rules that constrain the construction of open EFTs. I will conclude by outlining bottom-up implications, and how these principles provide a systematic route to causal, gauge-invariant open EFTs suitable for cosmological and gravitational applications.
Refs:
Gauging Open EFTs from the top down https://arxiv.org/abs/2512.17089
Schwinger-Keldysh path integral for gauge theories
https://arxiv.org/abs/2604.26941

The 21 cm forest, a series of narrow absorption features produced by neutral hydrogen against high-redshift radio sources, provides a unique probe of the thermal and small-scale structure of the early Universe. However, X-ray heating and dark-matter free streaming can both suppress small-scale absorption features, leading to degeneracies in conventional statistics.

In this talk, I will introduce the basic physics of the 21 cm forest and present a new approach based on topological data analysis. Using persistent homology, we characterize how absorption troughs appear, persist, and merge, and construct topological descriptors sensitive to heating and warm dark matter. We show that combining these descriptors helps break their degeneracy, while retaining useful information even in the presence of SKA1-Low-like thermal noise.

Relativistic viscous hydrodynamics is the workhorse for modeling the quark–gluon plasma (QGP) created in high-energy heavy-ion collisions and could play an equally crucial role in understanding hot, dense matter in neutron stars and their mergers. In contrast to commonly used Israel–Stewart–type (IS) theories, which can exhibit acausal behavior, we consider the Bemfica–Disconzi–Noronha–Kovtun (BDNK) formulation, equipped with well-defined causality conditions that are convenient for numerical implementation. We present two independent formulations that enable stable and accurate 3+1D simulations of the BDNK causal relativistic viscous hydrodynamic theory on arbitrary curved spacetimes. Both schemes are rigorously shown to be flux-conservative, strongly hyperbolic, locally well-posed, and mutually equivalent: one is a full first-order reduction augmented with auxiliary fields to enforce constraints, while the other is a mixed-order formulation that forgoes these fields and is more memory-efficient and markedly faster. We outline the underlying ideas and present a comprehensive validation of our numerical implementation through a suite of tests. Convergence and accuracy are demonstrated across all cases, including systems with semi-analytical solutions relevant to heavy-ion collisions and shock-tube benchmarks, with direct comparisons to standard IS-based approaches. In the low-viscosity limit, the code recovers stationary ideal-hydrodynamic solutions, including Bondi–Michel spherical accretion and equilibrium Kerr torus configurations, with negligible deviations from stationarity. We report progress toward developing a unified, open-source, performance-portable, GPU-ready codebase for simulating relativistic viscous fluids across QGP and astrophysical regimes.

[Abstract of Mahboubeh Shahrbaf Motlagh]
Strange particles are abundantly produced and studied in dedicated hadron and hypernuclear physics experiments at J-PARC, as well as in high-energy heavy-ion collision experiments such as HADES at GSI, ALICE at CERN, STAR at RHIC, and NA61/SHINE at CERN. These experiments provide valuable constraints on the properties of dense baryonic matter and hyperon interactions. Under the extreme densities reached in neutron star (NS) interiors, strange degrees of freedom are also expected to appear; however, their actual presence remains one of the most fundamental open questions in dense matter physics. Understanding their role is essential for constraining the equation of state (EoS) of strongly interacting matter and for connecting terrestrial measurements with astrophysical observations.
In the first part of this talk, I will briefly review my microscopic study of hyperonic matter within the lowest-order constrained variational (LOCV) framework. Using realistic spin- and parity-dependent ΛN and ΛΛ interactions constrained by hypernuclear data, I will discuss the resulting EoS and the macroscopic properties of NSs. The inclusion of Λ hyperons leads to a moderate softening of the EoS and reduces the maximum mass of NS, giving rise to the so-called hyperon puzzle. Possible mechanisms to resolve this puzzle will be discussed in light of current observational constraints from NICER and gravitational-wave measurements.
In the second part, I will consider a relativistic mean-field framework, specifically the DD2Y-T model, and explore how the inclusion of a deeply bound H-dibaryon-like particle, the so-called sexaquark with quark content uuddss, can modify the hyperonic EoS. This combined treatment of hyperons and sexaquarks highlights how these two strangeness-bearing components may jointly influence the internal composition and observable properties of NSs. Our results suggest that, for a favorable sexaquark mass range, the onset of sexaquark degrees of freedom in NS matter may facilitate an early transition to deconfined quark matter within a smooth crossover construction.

[Abstract of Dr. Davood Rafiei]
Dark matter makes up more than 85% of the matter in the Universe, yet its microscopic nature remains unknown. Neutron stars, because of their extreme density and strong gravity, provide unique natural laboratories to probe dark matter and other exotic degrees of freedom through multimessenger observations.
In this talk, I will discuss two approaches to probing dark-matter-admixed neutron stars. First, I will present a two-fluid framework in which normal neutron-star matter and sub-GeV self-interacting bosonic dark matter are treated as two separate fluids that interact only
through gravity. Depending on the dark matter mass, coupling strength, and fraction, the
dark component may form either a compact core or an extended halo, affecting the mass-radius relation, tidal deformability, and pulse-profile modeling. I will show how current multimessenger constraints can restrict the corresponding dark matter parameter space.
Second, I will discuss a single-fluid framework in which exotic or dark components are produced inside dense neutron-star matter and directly modify the effective equation of state. I will focus on f-mode oscillation frequencies, damping times, and quasi-universal relations, with applications to gravitational-wave asteroseismology. In this context, I
will consider hyperons, sexaquarks or deeply bound H-dibaryons, and deconfined quark matter. These studies show that exotic and dark components can leave observable signatures in future gravitational-wave detections.

The type IIB matrix model is expected to give a nonperturbative formulation of superstring theory. Its covariant derivative interpretation provides a method to describe curved spacetimes in the model. There, matrices are identified with certain covariant derivatives which can be viewed as infinite-size matrices. Here, by using the Berezin Toeplitz quantization, we develop a method to regularize these matrices as finite-size ones, which is needed to calculate quantum effects in the interpretation or in particular to apply the interpretation to the results of numerical simulations. As an example, we examine the case of S^2 in detail.

Masses and spins of hadrons are fundamental quantities in physics; however, their origins are not well understood, and their investigation is one of the major purposes of building electron-ion colliders (EICs) in the 2030’s. Both quantities can be investigated by generalized parton distributions (GPDs). In this seminar, I explain various experimental processes for measuring the GPDs and experimental possibilities at KEK. So far, the GPDs have been investigated mainly by the deeply virtual Compton scattering and deeply virtual meson production processes at charged-lepton accelerator facilities. They could be investigated by high-energy neutrino facilities in the future.

At KEK, it is possible to investigate the GPDs using the e^+ e^- collider KEKB and the hadron-accelerator facility J-PARC. We can extract the s-channel GPDs and gravitational form factors of hadrons by the two-photon processes gamma^* + gamma -> h + h-bar, where h is a hadron. Actually, there was the first report on the determination of gravitational form factors and radii from KEKB measurements in 2018. At J-PARC, the GPDs will be investigated by the exclusive Drell-Yan process pi^- p -> mu^+ mu^- B, where the baryon B could be a nucleon or Delta. In the future, other processes could be studied for the GPDs. For example, the 2->3 reaction processes NN -> N pi B could be used for probing the GPDs in the ERBL (Efremov-Radyushkin-Brodsky-Lepage) region.

Anomaly cancellation is one of the most fundamental consistency conditions in quantum field theory. In constructing models beyond the Standard Model, one must ensure the absence of anomalies that would render the theory inconsistent. Consequently, anomaly cancellation conditions impose strong constraints on the allowed matter content. Recent developments have made it possible to systematically study not only perturbative anomalies but also the more subtle global anomalies via bordism theory. This perspective has led to a deeper understanding of anomalies and their implications for model building. In this talk, I will discuss anomalies in family unification models, which provide a natural explanation for the three generations of quarks and leptons. We identify the relevant bordism groups that classify possible anomalies in these models and show that no global anomalies arise. We also revisit earlier studies of perturbative anomalies in these models dating back to the 1980s. This talk is based on joint work with Tsubasa Sugeno (Tohoku University), arXiv:2604.04393.

We investigate a novel type of asymmetric dark matter (ADM) model in which the dark matter asymmetry and the baryon asymmetry in our universe (BAU) are produced simultaneously via low-scale spontaneous leptogenesis, where the mass scale of the right-handed neutrino is much lower than the Davidson–Ibarra bound. In our scenario, both asymmetries are predominantly sourced by a dynamical CP phase, namely the majoron. Its kinetic misalignment provides a sufficiently large, time-dependent effective CP phase, allowing efficient asymmetry production even for low-mass right-handed neutrinos. In our framework, the sources of CP violation responsible for the BAU and ADM are correlated with each other, leading to a predictive relation for the dark matter mass. In particular, when the dark matter asymmetry reaches its equilibrium value before freeze-out, the dark matter mass is typically predicted to be of order GeV, which lies within the sensitivity of direct detection experiments. On the other hand, if the dark matter asymmetry does not reach its equilibrium value due to weak coupling, the allowed mass range extends over a broader interval, from GeV up to 10 TeV.