I will review symmetric mass generation (SMG), whereby fermions are gapped while preserving a chiral but necessarily non-anomalous symmetry. A simple model of SMG will be described, which leverages strongly-coupled gauge dynamics. I will then use bosonisation and dualities to derive the phase diagrams of a series of 2d Abelian gauge theories, including the 2d SMG model, in doing show establishing its validity. I will finally comment on the application of such constructions to symmetry-preserving boundary conditions and fermion-monopole scattering in 4d gauge theory.

Quantum many-body problems are ubiquitous in modern physics across a wide range of research fields. One of the most important challenges is the elucidation of dense matter properties relevant to neutron star physics. While numerous attempts have been made to address this problem within nuclear many-body theories, we pursue an alternative approach by exploiting an analogy with ultracold atomic systems. In this talk, we discuss a microscopic mechanism of the hadron-quark crossover that occurs in dense matter, drawing an analogy with the Bose-Einstein condensate to Bardeen-Cooper-Schrieffer (BEC-BCS) crossover established in ultracold atomic experiments. Moreover, we present our recent theoretical progress on a tunable three-body force in ultracold atoms, in analogy with the Fujita Miyazawa three-nucleon force.

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

Recently, there has been growing attention to applying quantum field-theoretic techniques, such as scattering amplitudes, to problems of classical gravity. It has led to the highest precision calculations of gravitational two-body systems, refined connections between classical and quantum physics, and a novel perspective on black holes. In this talk, we push forward this program to understand the physics of black holes, especially their horizons, at both classical and quantum levels. Central to this is the mass-changing amplitude, where a black hole transitions to a different mass state by absorption or emission. We discuss that this amplitude correctly describes mergers of two black holes, the horizon absorption of gravitational waves, and even the Hawking radiation, and serves as the building block for computing various observables of black holes.

In recent years, the infrared structure of gravity and gauge theories has been intensively studied via asymptotic symmetries, which are genuine physical symmetries rather than mere redundancies. Despite this progress, few works have explored the connection between asymptotic symmetries and the confinement phenomenon. In this talk, we examine the asymptotic symmetries of three-dimensional quantum electrodynamics (QED₃) and show that, under the assumption of confinement, their action on asymptotic states becomes trivial. This talk is based on Phys. Rev. D 112, 105001 (2025) [arXiv:2503.20173].

While studying dark matter scattering processes in the early Universe, usually, finite temperature effects are included through a thermal averaging of the zero temperature (vacuum) matrix elements,and through corrections to particle masses and phase-space densities in a thermal bath. In this talk, I shall discuss the additional finite temperature NLO corrections to the scattering matrix elements. In particular, approximate analytical forms of these corrections will be derived, which can then be conveniently incorporated in the Boltzmann integro-differential equations for the dark matter distribution function. I shall consider as an example scalar thermal loops to illustrate certain features of these corrections.

Cosmological observables provide powerful probes of physics beyond the Standard Model across a wide range of energy scales. In this talk, I will discuss how processes from different epochs of the early universe can leave observable imprints on key cosmological quantities. The annihilation of dark matter into neutrinos after neutrino decoupling, around the MeV scale or below, and the decoupling of light degrees of freedom from the thermal bath at a few hundred MeV or higher, can both influence the effective number of relativistic species, $\Delta N_{\rm eff}$. At much higher scales, post-inflationary dynamics, such as the production of dark matter or supermassive right-handed neutrinos, can affect the scalar spectral index, $n_s$. Together, these connections illustrate how cosmological measurements, spanning from the MeV scale to the inflationary epoch, can reveal signatures of new physics far beyond the reach of laboratory experiments.

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

Primordial black holes (PBHs) from Planck-mass to supermassive black holes produce a variety of interesting phenomena. I first present the PBH reformation process, where clouds of extremely light PBHs can recollapse into heavier PBHs before evaporating. By transitioning to a matter-dominated era, the formation probability of PBHs is greatly increased and does not therefore require any initial clustering. The larger reformed PBH population could survive to the present day, emitting high energy radiation potentially detectable by the next generation cosmic ray experiments. Chirping gravitational waves generated by O(10 M_sun) binary black hole mergers have been detected by the LIGO-VIRGO-KAGRA experiments, with speculation that some events are generated by PBH mergers. We show that the dark matter halo that accretes around PBHs can distinguish them from stellar evolution black holes, and gravitational lensing of chirping gravitational waves can reveal their extended structure and prove their primordial origin. I then present gas heating constraints on these dressed PBHs (PBH + dark halo) as well as other extended dark compact objects. In addition to modifying the point-mass dynamical friction formalism to include finite-size effects, the accretion disk emission sensitively depends on the object radius. Finally, I discuss a Friedberg-Lee-Sirlin Q-ball solution where the inclusion of a Yukawa force destabilizes the Q-ball at large charges. Surprisingly, the unstable Q-balls do not collapse under this attractive force but instead experience runaway expansion.

The statistical properties of the Cosmic Microwave Background (CMB) anisotropies, which reflect the curvature inhomogeneities of the early Universe, are well accounted for by assuming that these inhomogeneities emerged from amplified vacuum fluctuations. As they result from a genuine quantum process, it is natural to question which properties of these primordial inhomogeneities are inherently quantum and which, if any, have persisted until their observation despite interactions that induced decoherence, thereby rendering them classical. I will review the latest progress on these questions.

References:
Martin, J., Micheli, A., & Vennin, V. (2022). Discord and decoherence.
Journal of Cosmology and Astroparticle Physics, 2022(04), 051.
Micheli, A., & Peter, P. (2023). Quantum Cosmological Gravitational Waves? In C. Bambi, L. Modesto, & I. Shapiro (Eds), Handbook of Quantum Gravity (pp. 1-66).
Micheli, A., Oshima, Y., & Takahashi, T. (2025) Squeezing of cosmological perturbations in presence of decoherence, in preparation