In this talk, I will outline a fundamentally quantum description of bosonic dark matter. Following a quantum optics-inspired approach, I will show the density matrix of dark matter, which takes a mixed Gaussian form over a coherent state basis. This formalism also allows a precise description of quantities related to dark matter coherence. I will further give a continuous description of dark...
Recent progress in the electric dipole moment (EDM) measurements of the electron using the paramagnetic atom or molecule is remarkable. In this paper, we calculate a contribution to the electron EDM at three-loop level, introducing the CP-violating Yukawa couplings of new SU(2)$_L$ multiplets. At two-loop level, the Yukawa interactions generate a CP-violating dimension-six operator, composed...
We discuss triple $Z'$ boson signatures via the decay chain of $Z \to Z' \phi \to Z' Z' Z'$, with a new light scalar $\phi$, at future Z factories such as CEPC and FCC-ee. These new bosons $\phi$ and $Z'$ naturally appear in models with a new $U(1)$ gauge symmetry which is spontaneously broken and introduced in various new physics scenarios. The branching ratio of $Z \to Z' \phi \to Z' Z' Z'$...
Dark matter (DM) plays an important role in modern high-energy physics and indirect signals can provide evidence of DM interactions with Standard model (SM) particles. Among various of SM channels, gamma-rays are one of the most prominent channel because they head directly to the Earth unlike other charged cosmic-ray particles. Using gamma-ray data of Fermi-LAT, a space telescope that is cable...
Pseudo Nambu-Goldstone (pNG) bosons can play important roles in particle physics, such as being a light dark matter (DM), the QCD axion to solve the strong CP problem, and so on. I point out that such a pNG boson is naturally realized by the finite modular symmetry, which may originate from the geometry of extra dimensions in the superstring models. An accidental global U(1) symmetry arises...
A detection scheme is explored for light dark matter, such as axion dark matter or
dark photon dark matter, using a Paul ion trap system. We first demonstrate that
a qubit, constructed from the ground and first excited states of vibrational modes
of ions in a Paul trap, can serve as an effective sensor for weak electric fields due
to its resonant excitation. As a consequence, a Paul ion...
In this work, we have explored the conversion-driven freeze-out scenario, where the next-to-lightest stable particle (NLSP) sets the dark matter (DM) abundance through
the process ``NLSP SM $\leftrightarrow$ DM SM". Although DM is produced via
freeze-out mechanism, its interaction strength with the visible sector can
range from weak-scale to feeble-scale couplings. This leads to a vast,...
In this talk, we propose a new Higgs-portal dark matter scenario considering the Higgsplosion effect, which is a hypothesis of the significant production rate of high multiplicity of Higgs particles at high $\sqrt{s}$. Our scenario allows heavy Higgs-portal dark matter of $m_\chi\gtrsim{\cal O}(1)$ TeV, while the typical scenario indicates the order of ${\cal O}(10-100)$ GeV. We show that...
The possibility that the up quark mass is generated entirely through nonperturbative dynamics offers an elegant solution to the strong CP problem. In this talk, I will present a controlled calculation of the dynamically generated up quark mass in a class of QCD-like theories, based on supersymmetric QCD deformed by anomaly mediated supersymmetry breaking (AMSB). By matching the low-energy...
We consider the extension of the Standard Model with an inert scalar doublet, three right-handed neutrinos, and singlet scalar fields, φ and S. In this model, neutrino masses are zero in the limit of the unbroken Z4 discrete symmetry. We show that when the singlet scalar field φ gets a VEV, the Z4 symmetry is broken to Z2, and neutrino masses are generated at one-loops due to the mixings...
We investigate the origin of neutrino masses, focusing on theoretical models in which neutrinos are massive Majorana fermions.
Such neutrinos naturally lead to processes that violate the lepton number which is strictly conserved in the Standard Model.
We discuss the current constraints on such models from lepton number violating processes, such as neutrinoless double beta...
proposal): The search for baryon number violation offers a promising path to uncovering new physics. In this talk, we examine how measurements of different nucleon decay channels can shed light on the underlying theory. We first investigate the chirality structure of baryon-number-violating interactions through lifetime measurements of strangeness-conserving nucleon decay modes. Using an...
We derive the oscillation formula of Majorana neutrinos based on quantum field theory. Since the Hamiltonian under the Majorana mass term does not conserve lepton number, the eigenstates of lepton number change complexly over time. With the Bogoliubov transformation, we successfully relate the lepton number eigenstates at different times. This method enables us to understand the time evolution...
We consider charged lepton flavor violation (CLFV) via a light and weakly interacting boson and discuss the detectability by future proton and lepton beam dump experiments. We focus on three types of CLFV interactions, i.e., the scalar-, pseudoscalar-, and vector-type interactions, and calculate the sensitivities of beam dumps to each CLFV interaction. We show that a wide region of the...
We investigate a neutrino-scalar dark matter (DM) $\nu\phi$ interaction encountering distinctive neutrino sources, namely Diffuse Supernova Neutrino Background (DSNB) and Active Galactic Nuclei (AGN). The interaction is mediated by a fermionic particle $F$ , in which the $\nu\phi$ scattering cross section characterizes different energy dependent with respect to the kinematic regions, and...
In this talk, I will discuss future solar neutrino observatories and their role in measuring solar neutrino oscillation parameters. These observatories will also contribute to determining the structure of the Sun and the Earth through the study of day-night asymmetry. Solar neutrinos, produced via the pp-chain and CNO cycle, travel directly from the solar core to the Earth. Detecting these...
In this talk, we discuss the direct coupling of the Higgs boson to BSM particles at the future Muon Collider (MuC). At high-energy MuC, the processes we consider are naturally dominated by vector boson fusion (VBF), which emits high-rapidity muon pairs. Thus, by studying forward muon pairs, we can probe the coupling. Furthermore, due to the characteristics of VBF, we can determine whether the...
Dark matter (DM) is one of the main components of the universe and strongly related to the evolution of the universe. In order to understand the nature of DM, numerous direct and indirect search experiments are on-going or planned. The Intermediate Water Cherenkov Detector (IWCD), a near detector planned for Hyper-Kamiokande, is equipped with a vertically movable capability that enables the...
We explore quantum entanglement in top quark pair production at a photon collider realized via laser backscattering at an electron linear collider. By analyzing the $\gamma\gamma \to t\bar{t}$ process within the density matrix formalism, we quantify spin correlations and entanglement using concurrence and entropy-based measures. The high degree of control over photon polarization in this setup...
The QCD axion is a compelling mechanism for solving the strong CP problem. Most studies have focused on axion models with a large decay constant, $(f_{a}\gtrsim 10^{9}\,\mathrm{GeV})$. However, recent work has pointed out that viable axion models may also exist for $(f_{a}\sim1\,\mathrm{GeV}$). In our research, we derive stringent constraints on this axion scenario from kaon decay measurements.
Axions provide a compelling solution to the strong CP problem and a viable candidate for dark matter. We explore their realization in a minimal five-dimensional $M_4 \times S^1/\mathbb{Z}_2$ orbifold framework. An explicit one-loop Casimir energy calculation reveals that the irreducible axion potential induced by worldline instantons is exponentially suppressed, thereby ensuring a high-quality...
Although the Higgs boson has been discovered, its couplings to Standard Model (SM) particles may deviate from SM predictions. Such deviations can arise in extensions of the SM, including those that modify the Higgs sector. In particular, extended Higgs models often exhibit different shapes of the Higgs potential depending on their structure. In this work, we focus on near-aligned extended...
We study the signature of the final stage of the evaporation of primordial black holes (PBH), focusing on high energy neutrinos and gamma-rays. For distributions of PBH with finite widths in mass spectrum, we derive a new upper limits $f_{\rm PBH} \lesssim 10^{-4} - 1$ for $M_{\rm PBH} = 10^{15-20}$ g by utilizing the IceCube latest data set of diffuse neutrinos for $E_\nu \geq 30$ TeV. We...
n the WIMP framework, the Higgs portal has a relatively small Higgs–nucleon interaction compared to other mechanisms, and, since the mediator is the Higgs boson, it is subject to fewer theoretical constraints. However, recent improvements in the precision of direct detection experiments have placed increasing pressure on Higgs-portal dark matter models. In simple models, the preferred DM mass...
Cosmic inflation was introduced to address several shortcomings of the standard Big Bang cosmology. The observed red tilt of the CMB power spectrum and potential future detection of primordial gravitational waves could provide valuable clues to reconstructing the inflaton potential. Recent small scale CMB measurements from the Atacama Cosmology Telescope (ACT), combined with Planck data,...
Cosmic strings are one-dimensional topological defects that arise from the spontaneous symmetry breaking in the early universe. In particular, superconducting cosmic strings, which have attracted attention from an astrophysical perspective, are characterized by their interactions with matter fields and are thought to have formed during the grand unification epoch. Cosmic strings have been...
BlackHawk is a widely used tool for computing the secondary spectra of particles emitted via Hawking radiation from evaporating black holes. In order to account for particle hadronization and decay processes, it employs different computational backends—such as Hazma, PYTHIA, and HDMSpectra—depending on the energy scale of the initial emission. While effective in separate regimes, this hybrid...
We present a unified study of vector dark matter (VDM) from hidden gauge symmetries U(1)D or SU(2)D. Starting from the renormalizable Higgs-portal UV theory for VDM with a dark Higgs field, we integrate out the radial mode of the dark Higgs to derive the leading low-energy interactions for Higgs-portal VDM, which are constrained into the validity domain in the UV theory. We also make the VDM...
In the standard model, the mechanism for gauge symmetry breaking and the theoretical origin of the Higgs boson remains unclear.
Non-Abelian gauge theories in higher dimensions are good candidates to address this issue.
We have constructed a Non-Abelian gauge theory with extra dimensions of two-dimensional sphere. In this model, compared to conventional models such as those with $S^1$ and...
COSINE-100 is an experiment designed to search for dark matter interactions using an array of scintillating NaI(Tl) crystals, which serve as both the WIMP interaction target and detector. We have found that contamination on the crystal surface affects the energy range of the dark matter signal. To improve the performance of detectors, we have developed cleaning methods using organic solvents...
We propose a novel and comprehensive particle physics framework that addresses multiple cosmological tensions observed in recent measurements of the Hubble parameter, S8, and Lyman-α forest data. Our model, termed `{\bf SIDR+zt}' (Self Interacting Dark Radiation with transition redshift), is based on an inelastic dark matter (IDM) scenario coupled with dark radiation, governed by a U(1)D gauge...
Dark matter (DM) environments around black holes (BHs) can influence their mergers through dynamical friction, causing gravitational wave (GW) dephasing during the inspiral phase. While this effect is well studied for collisionless dark matter (CDM), it remains unexplored for self-interacting dark matter (SIDM) due to the typically low DM density in SIDM halo cores. In this work, we show that...
We investigate dark gauge-mediated supersymmetry breaking with an unbroken U(1) gauge symmetry and a massless dark photon. Messengers charged under both Standard Model and dark gauge groups generate new soft SUSY-breaking terms via gauge kinetic mixing. Large mixing significantly alters superpartner spectra compared to standard GMSB, reduces the μ parameter, and predicts a relatively light...
Primordial black holes (PBHs) formed during the early universe provide a unique probe of physics beyond the Standard Model. In this study, we investigate the impact of additional degrees of freedom from supersymmetry (SUSY) particles and the memory burden effect (MBE) on the evaporation process of PBHs formed via first-order phase transitions. By analyzing how these factors influence the PBH...
If the B – L symmetry is gauged with the addition of right-handed neutrinos, the standard model B – L current is anomalous with respect to the B – L gauge field itself. Then, the anomaly relation implies that the magnetic helicity of the B – L gauge field is related to the standard model B – L charges, although the whole universe is B – L neutral with right-handed neutrinos. Based on this, we...
We propose a hybrid inflationary scenario based on eight-flavor hidden QCD with the hidden colored fermions being in part gauged under U(1) B-L symmetry. This hidden QCD is almost scale-invariant, so-called walking, and predicts the light scalar meson (the walking dilaton) associated with the spontaneous scale breaking, which develops the Coleman-Weinberg (CW) type potential as the consequence...
We consider the boosted dark matter(BDM) model that consists of two-component dark matter with the boost effect from the annihilation of heavier DM into lighter one and the self-heating effect from the self-interaction of lighter DM. These effects suppress the formation of small-scale structures, and this suppression affects 21cm signal. We expect that BDM model will change 21cm signal and...
We present a minimal setup within the framework of Horndeski gravity that describes a nonpathological Genesis scenario. Our setup allows for a fully stable transition to the kination epoch, during which General Relativity (GR) is restored. This Genesis scenario circumvents the no-go theorem, albeit at the cost of encountering the risk of strong coupling in the past. Interestingly, our scenario...
We investigate the electroweak phase transition (EWPT) and collider phenomenology in the Two-Higgs-Doublet Models (2HDM). The interplay between the thermal properties of the scalar potential and experimental constraints offers a promising framework to explore beyond the Standard Model physics. We analyze scenarios that may realize a strong first-order phase transition (SFOPT), which is...
We propose a new collider signature for neutral long-lived particles (LLPs): an emerging photon jet in the hadronic calorimeter (HCAL), from LLP decays to photons with no ECAL activity or tracks. Using the ultralight fermiophobic Higgs $h_f$ in the Type-I 2HDM as a benchmark, we study
$pp \to H^\pm h_f \to W^\pm h_f h_f$
where one $h_f$ decays in the ECAL and the other in the HCAL. Fast...
We study the possibility of probing leptogenesis via stochastic gravitational waves (GW) arising from a dark sector assisted first-order electroweak phase transition. The same dark sector, with non-trivial transformation under an unbroken $Z_2$ symmetry is also responsible for providing the only source of CP asymmetry via one-loop interference with the tree level decay of a heavy right-handed...
This study explores a dark matter model in which a pseudo-Nambu-Goldstone boson arises as a viable dark matter candidate from the spontaneous and soft breaking of global $U(1)$ symmetries and stabilized by a residual $\mathbb{Z}_3$ discrete symmetry. The model introduces three complex scalar fields, singlets under the Standard Model gauge group, and charged under a dark $U(1)_V$ gauge symmetry...
We show that a phase transition may take place in the early Universe at a temperature $T_*$ resulting a temperature dependent mass for right handed neutrinos (RHN) which finally relaxes to a constant value after electroweak symmetry breaking (EWSB). As a result, a requisite amount of lepton asymmetry can be produced near $T_*$ satisfying the observed baryon asymmetry of the Universe via...
Minimal Flavor Violation (MFV) offers an appealing framework for exploring physics beyond the Standard Model. Interestingly, within the MFV framework, a new colorless field that transforms non-trivially under a global ${\rm SU}(3)^3$ quark flavor group can naturally be stable. Such a new field is thus a promising dark matter candidate, provided it is electrically neutral. We extend the MFV...
Models of multi-component dark matter can explain small-scale problems through the presence of self-interaction. We propose a model where DM consists of two scalar fields stabilized by a Z4 symmetry and which can take part in annihilation or semi-annihilation processes. Some of these scatterings can be Sommerfeld enhanced through the u-channel without the need of a light mediator. The...
In this study, we show that thermal leptogenesis can be realized within the framework of the $SO(10)\times U(1)_A$ grand unified theory(GUT). Furthermore, by including flavor effects, we have found that the second-lightest right-handed neutrino makes a significant contribution. As a result, the mass derived in this study is approximately six times larger than the mass predicted for the...
A dark matter model with QCD-like SU(N) gauge symmetry and electroweakly interacting dark quarks is discussed. In this model, the lightest G-parity odd dark pion is a main component of dark matter. I will discuss the relation between the mass spectrum of dark pions and annihilation channels which mainly contribute to the relic abundance. When the masses of dark matter and heavier dark pions...
We study quantum decoherence of curvature perturbations at superhorizon scales caused by the gravitational nonlinearities. We show that cubic gravitational couplings, constrained by the spatial diffeomorphism invariance, lead to infrared (IR) and ultraviolet (UV) divergences in the decoherence rate at one loop. These divergences arise from fluctuations of deep IR modes which look like a...
In recent years, an increasing number of studies have focused on using gravitational waves to explore axions and the dynamics of Peccei-Quinn symmetry breaking at high energy scales in the early universe. To accurately quantify the capability of specific gravitational wave experiments to probe the axion properties, it is crucial to perform precise calculations of gravitational wave signals...
We propose an explanation for the recently reported ultra-high-energy neutrino signal at KM3NeT, which lacks an identifiable astrophysical source. While decaying dark matter in the Galactic Center is a natural candidate, the observed arrival direction strongly suggests an extragalactic origin. We introduce a multicomponent dark matter scenario in which the components are part of a...
The true identity of dark matter (DM) is an unsolved problem in physics. Among the various DM candidates, weakly interacting massive particles (WIMP) are attractive because their abundance can be explained thermally. The WIMP abundance can be estimated using the Boltzmann equation, and particle masses at zero temperature are usually adopted. In this study, we take into account the electroweak...
Employing effective field theory techniques, we advance computations of thermal parameters that enter predictions for the gravitational wave spectra from first-order electroweak phase transitions. Working with the real-singlet-extended Standard Model, we utilize recent lattice simulations to confirm the existence of first-order phase transitions across the free parameter space. For the first...
We consider higher-dimensional uniform inflation, in which the extra dimensions expand at the same rate as three-dimensional non-compact space during inflation. We compute the cosmological perturbation in $D+4$ dimensions and derive the spectral index $n_s$ and the tensor-scalar ratio $r$. We analyze five inflationary models: chaotic inflation, natural inflation, quartic hilltop inflation,...
We study a mechanism to make dark matter stable based on the Pauli blocking in the fermion background. In the background where fermions occupy the states, the decay of dark matter to those final states is not allowed, as a result, DM becomes stable.
We derive the evolution equations of the distribution function in the quantum field theory and compare it with the Boltzmann equation.
We apply...
An axion coupled to both the Higgs field and electroweak gauge fields can generate the observed matter-antimatter asymmetry via electroweak baryogenesis, if its decay constant lies between $10^5$ and $10^7$ GeV. However, the axion remains constrained by astrophysical and cosmological bounds. In this talk, we introduce the intriguing possibility that the axion is also coupled to dark photons....
We propose a leptogenesis scenario where baryon asymmetry is generated from the rotation of the QCD axion in the PQ pole inflation scenario. The rotation originating from PQ explicitly breaking terms corresponds to the asymmetry of the PQ charge and is converted into the baryon asymmetry by the inverse decay of a right-handed neutrino. We show the correlation between the reheating temperature,...
With recent breakthroughs in deep learning, particularly in areas like natural language processing and image recognition, AI has shown remarkable abilities in understanding complex patterns. This raises a fundamental question: Can AI grasp the core concepts of physics that govern the natural world?
In this talk, as a first step towards addressing this question, we will discuss the possibility...
The recently observed very high energy (VHE) photons,GRB221009A, require a physics explanation beyond the standard model. Such energetic gamma ray bursts, originating from yet unknown very distance source at redshift z = 0.1505, would be directly scattered by extragalactic background lights (EBL) rendering its improbable detection at the earth. We show that dark photon which resides in extra...
Many recent studies of cosmic strings highlight the importance of investigating them within the framework of field theory to better understand their properties. In this talk, we show how the shape of scalar potential influences the interaction between strings. Although many works of cosmic strings assume that the Mexica-hat potential to break $U(1)$ symmetry, various types of potentials are...
While analytical methods remain fundamental in physics, many phenomena require computational approaches to be fully understood. In early universe cosmology, this necessity becomes paramount: understanding post-inflationary dynamics—including resonant particle production, backreaction, and rescattering—demands numerical solutions beyond perturbative methods.
We employ lattice simulations on...
In this talk, we will explore warm inflation in the early universe using two frameworks: Barrow holographic dark energy and teleparallel-based $f(T)$ gravity. Warm inflation assumes continuous interaction between radiation and the inflaton field, allowing for a sustained thermal bath during inflation and naturally solving the graceful exit problem. In our work, warm inflation is realized in a...
Light dark matter (DM) with mass around the GeV scale faces weaker bounds from direct detection experiments. If DM couples strongly to a light mediator, it is possible to have observable direct detection rate. However, this also leads to a thermally under-abundant DM relic due to efficient annihilation into light mediators. We propose a novel scenario
where a first-order phase transition...
The Inert Doublet Model (IDM) and Inert Triplet Model (ITM) feature a neutral scalar dark matter candidate along with inert charged scalars. In the ITM, the charged scalars exhibit a compressed mass spectrum, while in the IDM, the mass splittings among scalar components arise from electroweak symmetry breaking. Recent constraints from direct and indirect dark matter searches push these models...
In this talk, I will provide an overview of our work on cosmology in the presence of scalar fields, focusing on symmetric teleparallel gravity. Using dynamical system analysis, we investigate the late-time evolution of the universe within this framework.
I will begin with a concise introduction to symmetric teleparallel gravity, tracing its conceptual development from Weyl geometry to...
The detection of gamma-ray signals from primordial black holes (PBHs) could provide compelling evidence for their role as a dark matter candidate, particularly through the obser- vation of their Hawking radiation. Future gamma-ray observatories, such as e-ASTROGAM, and the next-generation telescopes, are poised to explore this possibility by measuring both Standard Model (SM) and beyond-the-SM...
