Nuclear Lattice Effective Field Theory (NLEFT) is a robust framework that integrates lattice techniques, effective field theory, and quantum Monte Carlo (QMC) algorithms to provide ab initio solutions to the nuclear many-body Schrödinger equation. This talk will introduce the fundamental principles of NLEFT and highlight recent advancements, including a novel solution to the Monte Carlo sign problem in nuclei, the renormalization group (RG) evolution of lattice-regulated nuclear EFT, and various applications for computing key nuclear observables. These developments demonstrate the framework’s efficiency and versatility in tackling complex challenges in nuclear many-body physics.

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

Several low energy observables such as the muon g-2, the proton radius or parity-violating electron scattering are pushing the intensity frontier of particle physics, demanding precise control of the scattering processes behind them. McMule is a Monte Carlo framework built to meet this challenge. By combining automated tools with effective field theory techniques, it delivers NNLO predictions in QED and has recently been extended to systematically include electroweak and non-perturbative effects. This makes McMule a powerful tool for the most ambitious precision experiments at lepton facilities, such as KEK. I will highlight our biggest challenges, the underlying methods, and the path forward.

Radiative transfer is a fundamental tool in astrophysics for understanding physical states and formation processes of various objects. In this talk, I will demonstrate how similar principles can be applied to a distant field—medical diagnostics using near-infrared light. Biological tissues are highly scattering media, analogous in some respects to dusty astrophysical systems, where photons undergo complex trajectories before reaching the observer. By adapting the techniques in the astrophysics research, we have developed a new radiative transfer code, TRINITY, that can simulate time-resolved photon transport in the human head and enables us to address the associated inverse problem. I will present our simulation results and their integration with machine learning, which enables rapid identification of bleeding sites. Our AI-based diagnostic model achieves an accuracy of over 90% in detecting bleeding sites. Finally, I will discuss ongoing efforts toward practical applications, including early-stage detection of brain hemorrhage, and future directions for interdisciplinary research connecting physics and medicine.

State-of-the-art atomic clocks achieved fractional uncertainties below 10^-18. In these clocks, effects of conventional external fields, such as electric and magnetic fields, are suppressed for the high accuracy. Under this condition, the system can potentially be sensitive to tiny energy shifts caused by hypothetical fields weakly coupled to ordinary matter or by effects mediated by massive particles. Based on this idea, various searches for new particles and fields are performed using precision spectroscopy.
In this seminar, starting from the overview of precision spectroscopy of atoms and its applications to fundamental physics searches, I will describe some major recent progress in the field. Particularly, I focus on the topics related to the new clock transition at 431 nm in ytterbium that has high sensitivity to variation of the fine structure constant and fifth forces between a neutron and an electron.

We ask the question of how angular momentum is conserved in a number of related processes, from elastic scattering of a circularly polarized photon by an atom, where the scattered photon has a different spin direction than the original photon; to scattering of a fully relativistic spin-1/2 particle by a central potential; to inverse beta decay in which an electron is emitted following the capture of a neutrino on a nucleus, where the final spin is in a different direction than that of the neutrino – an apparent change of angular momentum.

The seeming non-conservation of angular momentum arises, in fact, in the quantum measurement process in which the measuring apparatus does not have an initially well-defined angular momentum, but is localized in direction in the outside world. We generalize the discussion to massive neutrinos and electrons, and examine nuclear beta decay and electron-positron annihilation processes through the same lens, enabling physical insights into angular and helicity distributions in these reactions.

Primordial black holes (PBHs), hypothesized to have largely been produced in the early Universe, span a broad mass range and offer rich cosmological and astrophysical implications. Among them, there has been a recent growing interest in the evaporating PBHs, looking for the cosmological consequences of their past existence and observable signatures. In this talk, I will provide a brief overview of PBHs and the physics of their evaporation. Then, I will introduce my works on evaporating PBHs, about their reformation, isocurvature generation, and dark matter and hotspots. These examples are just a fraction of the phenomenological side of the rich physics of PBHs.

Cosmic inflation is known to address problems in the Big Bang theory and to generate the fluctuations that seed the current cosmological structures. Its existence is strongly suggested by the Planck observation of the cosmic microwave background (CMB). Though the CMB observation implies small fluctuations on large scales, large fluctuations may be realized on a smaller scale and the primordial black holes (PBHs) may be made by their gravitational collapse. PBHs have gotten much attention lately as candidates for dark matter and may be searched for by LISA in future probes. However, the detailed analysis of the PBH formation from inflation requires a lot of assumptions, particularly in the statistics of the primordial curvature perturbations.
In this talk, I introduce a numerical lattice simulation of inflation in the stochastic approach (STOLAS: STOchastic LAttice Simulation). It enables us to know the true statistics of the curvature perturbation and predict the accurate statistic of PBH in each inflation model.
I show examples in some models. I also describe the importance sampling technique to sample efficiently the large perturbation related to PBH formation.

Friday, March 27 (13:30-15:00, room 1)
Lecture 1: Foundations of Machine Learning
Monday, April 6 (13:30-15:00, room 3)
Lecture 2: Multi-Layer Perceptron (MLP)
Friday, April 10 (13:30-15:00, room 3)
Lecture 3: Convolutional Neural Network (CNN)
Tuesday, April 21 (13:30-15:00, room 1)
Lecture 4: Self-supervised and Semi-supervised Learning (optional)
Tuesday, April 28 (13:30-15:00, room 1)
Lecture 5: Transformers and Large Language Models (LLMs)

The Peccei–Quinn (PQ) mechanism is a prominent solution to the strong CP problem. However, it faces the axion quality problem: higher-dimensional, Planck-suppressed operators which explicitly break PQ symmetry can reintroduce the effective QCD theta angle. In composite axion models, where strong dynamics at high energies dynamically break PQ symmetry, certain constructions address this quality problem.
In some cases, hidden interactions distinct from QCD appear to contribute to the axion mass through instanton effects. I demonstrate that while these small instantons enhance the axion mass in a toy model, they do not contribute to the axion mass in an explicit model which addresses the quality problem. This talk is based on the following work: https://arxiv.org/abs/2404.19342″