Quantum sensing offers significant advantages over classical techniques when detecting extremely weak signals, such as those from dark matter, by leveraging entanglement and superposition to achieve greater sensitivity and precision. There are two main approaches in quantum sensing: adapting classical signal processing methods to the quantum domain and developing novel quantum algorithms and protocols. In the first approach, I will present my recent work on measuring dark matter properties and ongoing efforts to minimize measurement noise. In the second approach, I will explore how quantum entanglement can enhance measurement sensitivity beyond classical limits, as well as discuss additional applications, including quantum sensing with error correction and quantum data processing.

We investigate the independent chiral zero modes on the orbifolds from fixed point theorems. The required information for this calculation includes the fixed points of the orbifold and the manner in which the spatial symmetries act on these points, unlike previous studies that necessitated the calculation of zero modes. Since the fixed point theorems can be applied to any fermionic theory on any orbifold, it allows us to determine the index even on orbifolds where the calculation of zero modes is challenging or in the presence of non-trivial gauge configurations. We compute the indices on the T2 and T4 orbifolds as examples. Furthermore, we also attempt to compute the indices on a Coxeter orbifold related to the D4 lattice.

Our understanding of gravitational waves produced by isolated astrophysical systems is primarily based on gravitational perturbation theory off a flat spacetime background. This leads to the common identification of gravitational radiation with massless spin-2 waves. In this talk, I will argue that gravitational waves may no longer be solely “spin-2” in character once the background spacetime is our expanding universe instead. As a result of the mixing between gravitational and other degrees of freedom, scalar “spin-0” gravitational waves may exist during the radiation-dominated epoch of our universe; as well as during its current accelerated expansion phase — provided the main driver is not the cosmological constant, but some extra “Dark Energy” field. Moreover, during the radiation-dominated era, spin-0 Cherenkov gravitational waves may even be generated if its material source were traveling faster than 1/\sqrt{3}.

The annihilation cross section of dark matter has an important role in dark matter phenomenology. If dark matter couples to a light force mediator, the exchange of the mediator non-perturbatively distorts the wave function of the dark matter from the plane wave. This effect significantly modifies the annihilation cross section. This effect is called Sommerfeld effect. In this talk, I will talk about how the annihilation cross section with Sommerfeld effect is calculated from the Schroedinger equation. Our method is consistent with the partial wave unitarity bound and it can be applied to s-wave and higher-ell waves.

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

Pseudo-Nambu-Goldstone bosons (pNGBs) are considered theoretically very promising dark matter candidates because their symmetry structure naturally suppresses interactions with the Standard Model, making them highly consistent with the latest experimental constraints. However, due to their weak interactions, the verifiability of pNGB dark matter is extremely low, and a new approach is essential to prove its existence. This talk aims to overcome this dilemma by proposing a new minimal model that incorporates an “”acceleration mechanism”” within the dark sector.
While we found that the semi-annihilation mechanism itself did not provide sufficient acceleration, it successfully demonstrated the importance of such an acceleration mechanism for the direct detection of pNGB dark matter.

Recent experimental discoveries of hadron resonances, many of which are classified as exotic hadrons, imply various structures of different natures. Typically, one is based on quark and colored interactions which results in a compact structure, while the other on hadrons and their interactions which results in a spatially extended structure. In general, these different natures mix and coexist. In fact, there are several evidences that indicate such mixing. In this talk, we show several examples of such coexistence for hadrons including X(3872), Omega(2012) and Omega_c families.

Measurements of $R_{D^{(*)}}={\rm{BR}}(B\to D^{(*)} \tau\bar\nu)/{\rm{BR}}(B\to D^{(*)} \ell\bar\nu)$ have shown deviations from the SM predictions at the 3.8$\sigma$ level. These results may suggest contributions from new physics, leading to an excess of the tau lepton modes. In contrast, the recent measurement of $R_{\Lambda_c} ={\rm{BR}}(\Lambda_b\to\Lambda_c\tau\bar\nu)/{\rm{BR}}(\Lambda_b\to\Lambda_c\ell\bar\nu)$ is consistent with the SM prediction. Such a situation motivates investigations into potential shortcomings in the experimental data and SM predictions. In this talk, we propose $b \to c$ semileptonic sum rules that provide relations between the decay rates of $B \to D^{(*)} \tau\bar\nu$ and $\Lambda_b \to \Lambda_c \tau\bar\nu$. Starting from the heavy quark and zero-recoil limits, we outline the derivation of the sum rule. We then examine deviations from these limits and study corrections arising from realistic hadron masses and higher-order contributions to form factors, while taking account of uncertainties. It is shown that these corrections are negligible compared to current experimental uncertainties, indicating that the sum rule is useful for cross-checking experimental consistency and testing the validity of the SM predictions. We also discuss future prospects.

Tidal Love numbers quantify the deformability of compact objects under external tidal fields and are key quantities in gravitational‑wave astronomy. They are essential for accurately modeling waveforms during the final orbits of an inspiral and are tightly connected to the microphysics of the compact object. At linear order, the tidal Love numbers of Schwarzschild black holes are famously zero. I will show that this property persists beyond linear order. In contrast, neutron stars exhibit a finite tidal response that encodes information about their internal structure, including their equation of state. I will present a framework for computing their tidal Love numbers beyond linear order. As I will discuss, these calculations rely on carefully matching relativistic perturbation theory of compact objects with the worldline effective field theory approach used to define their tidal deformability.

Symmetry is one of the most fundamental principles in nature, but where does it come from? Considering two distinct physical systems, 1) non-relativistic scattering of neutrons and protons in low-energy QCD and 2) relativistic scatterings of Higgs bosons in two-Higgs-doublet models, we show that the suppression, or maximization, of entanglement leads to enhanced symmetries in the underlying systems. These findings suggest a new paradigm to understand the origin of symmetry from the perspective of quantum information.