dark matter particles are the most likely explanation to the formation of large-scale-structures in the universe. I’ll review the body of evidence and the progress in the field
We revisit the Higgs-invisible decay branching ratio in Higgs-portal dark matter models. If the mass of the dark matter is slightly below the half of the mass of the Higgs boson, then pairs of the DM particles annihilate into the SM particles efficiently thanks to the Higgs resonance. The DM-Higgs coupling is required to be small to obtain the right amount of the dark matter relic abundance....
A pseudo-Nambu-Goldstone boson (pNGB) is an attractive dark matter candidate escaping naturally the severe direct ditection constraint. In the previous work, we discussed pNGB dark matter from gauged U(1)_{B-L} model. In this work, we will consider the further UV completion of the pNGB dark matter model via embedding to a SO(10) grand unified theory. The grand unification determines the some...
We propose a new mechanism to communicate between fermion dark matter and the Standard Model (SM) only through the four-form flux. The four-form couplings are responsible for the relaxation of the Higgs mass to the correct value and the initial displacement of the reheating pseudo-scalar field from the minimum. We show that the simultaneous presence of the pseudo-scalar coupling to fermion...
Dark, chiral fermions carrying lepton flavor quantum numbers are natural candidates for freeze-in. Small couplings with the Standard Model fermions of the order of lepton Yukawas are ‘automatic’ in the limit of Minimal Flavor Violation. In the absence of total lepton number violating interactions, particles with certain representations under the flavor group remain absolutely stable. For...
We study the inclusion of new heavy fermions on complex scalar dark matter (DM) phenomenology within gauged two Higgs doublet model (G2HDM). We find that for DM mass above 1 TeV, heavy quarks coannihilations into the Standard Model (SM) quarks and gluons dominate the thermally-averaged cross section relevant for the relic abundance of complex scalar DM. We demonstrate that the effects of QCD...
Real scalar triplet dark matter, which is known to be an attractive candidate for a thermal WIMP, is comprehensively studied paying particular attention to the Sommerfeld effect on the dark matter annihilation caused by the weak interaction and the other interaction between the dark matter and the Higgs boson. We find a parameter region that includes the so-called 'WIMP-Miracle' one is still...
We consider the renormalizable leptophilic WIMP models with the scalar mediators which have lepton numbers. We perform a comprehensive analysis for such a WIMP scenario for two distinct cases with SU(2) doublet or singlet mediators considering all the relevant theoretical, cosmological and experimental constraint at present. We show that mono-photon search at near-future lepton collider...
GUM is a recent addition to the GAMBIT framework that auto-generates the necessary code to run global scans of BSM models. By reducing the time to setup global scans, GUM removes one of the barriers to studying many models simultaneously. In this work I demonstrate an application of this to multiple simplified dark matter models at once. I will discuss scans that include a range of observables...
The dark photon is a massive hypothetical particle that interacts with the Standard Model by kinetically mixing with the visible photon. For small values of the mixing parameter, dark photons can evade cosmological bounds and be a viable dark matter candidate. Due to the similarities with the electromagnetic signals generated by axions, several bounds on dark photons are simply...
A novel mechanism of boosting dark matter by cosmic neutrinos is proposed. The new mechanism is so significant that the arriving flux of dark matter in the mass window 1 keV ≲ m_{DM} ≲ 1 MeV on Earth can be enhanced by two to four orders of magnitude compared to one only by cosmic electrons. Thereby we firstly derive conservative but still stringent bounds and future sensitivity limits for...
I will give a brief review on BSM physics.
The Fermilab Muon $g−2$ experiment reported the results of its Run-1 measurement of the anomalous magnetic moment $a^{FNAL}_\mu$, which is in full agreement with the previous BNL measurement and pushes the world average deviation $\Delta a^{2021}_\mu$ from the Standard Model to a significance of $4.2\sigma$. In this talk I will present an extensive survey of its impact on beyond the Standard...
We study the scenario of the two Higgs doublet model, where the Higgs potential respects the twisted custodial symmetry at high energy scale. In this scenario, experimental data for the Higgs boson couplings and those for the electroweak precision observables can be explained even when the masses of the extra Higgs bosons are near the electroweak scale. We also discuss the predictions on the...
We construct a supersymmetric flipped SU(5) grand unified model that possesses an R symmetry. This R symmetry forbids dangerous non-renormalizable operators suppressed by a cut-off scale up to sufficiently large mass dimensions so that the SU(5)-breaking Higgs field develops a vacuum expectation value of the order of the unification scale along the F- and D-flat directions, with the help of...
Sum rules in the lepton sector provide an extremely valuable tool to classify flavour models in terms of relations between neutrino masses and mixing parameters testable in a plethora of experiments. In this talk we present our recent work on this.
We investigate the possibility of simultaneously explaining inflation, the neutrino masses and the baryon asymmetry through extending the Standard Model by a triplet Higgs. The neutrino masses are generated by the vacuum expectation value of the triplet Higgs, while a combination of the triplet and doublet Higgs' plays the role of the inflaton. Additionally, the dynamics of the triplet, and...
We propose a scenario of spontaneous leptogenesis in Higgs inflation with help from two additional operators: the Weinberg operator (Dim 5) and the derivative coupling of the Higgs field and the current of lepton number (Dim 6). The former is responsible for lepton number violation and the latter induces chemical potential for lepton number. The period of rapidly changing Higgs field,...
Recent findings on the Higgs-R2 inflationary scenario have significantly increased. Here we focus on the deep-R2 parameter region of the model and report its reheating behavior, comparing with other parameter regions and discuss its phenomenological consequences.
We study a generalized superconformal model that gives rise to a subcritical regime of D-term hybrid inflation. Formulating the model in a Jordan frame, the effective potential of the subcritical regime is derived in the Einstein frame. It turns out the inflaton-waterfall field dynamics leads to various types of inflaton potential. Consequently the tensor-to-scalar ratio is found to range from...
During inflation, a scalar field undergoes a quantum diffusion following the de-Sitter temperature. Aided by the greater Hubble rate at higher potential, the quantum diffusion can make the global distribution of the field climb up the potential. If the potential exhibits a criticality at the maximum point, the field distribution can be sharply located near there. We show a possibility from QCD...
The basics of the LHC experiment and prospects for HL-LHC will be discussed.
The measurement of the quartic coupling between a Higgs boson pair and a vector boson pair is expected to be achieved from vector-boson fusion (VBF) production of a Higgs boson pair at the LHC. However, this process involves another unmeasured parameter, the trilinear Higgs self-coupling. Since the LHC cannot avoid the gluon fusion pollution, which becomes severe for anomalous Higgs trilinear...
In the SM, it is assumed that there is only one kind of scalar field, the isodoublet with Y=1/2. On the other hand, many models beyond the SM include extensions of the scalar potential, and some of them predict the charged scalar states. One of interesting candidates is the doubly charged scalar bosons from the isodoublet with Y=3/2. However, phenomenology of them had not been fully...
We investigate the prospect of searching for new physics via the novel signature of same-sign diboson + \slashed{E}_{T} at current and future LHC. We study three new physics models: (i) natural SUSY models, (ii) type-III seesaw model and (iii) type-II seesaw/Georgi-Machacek model. In the first two class of models, this signature arises due to the presence of a singly-charged particle which...
We analyze CP-violating effects in both electric dipole moment (EDM) measurements and future analyses at the Large Hadron Collider (LHC) assuming a two-Higgs-doublet model (2HDM) with “soft” CP violation. Our analysis of EDMs and current LHC constraints shows that, in the case of Type II and Type III 2HDMs, an O(0.1) CP-violating phase in the Yukawa interaction between H1 (the 125 GeV Higgs...
We study capability of the ILC beam dump experiment to search for new physics, comparing the performance of the electron and positron beam dumps. The dark photon, axion-like particles, and light scalar bosons are considered as new physics scenarios, where all the important production mechanisms are included: electron-positron pair-annihilation, Primakoff process, and bremsstrahlung...
We study the prospects of searching for leptophilic gauge bosons (LGBs) associated with a new U(1) gauge symmetries at ILC beam dump experiment. When the LGBs are light and weakly interacting, we show a significant number of signals can occur at ILC beam dump experiment and we can cover the parameter region which has not been explored yet. .
We investigate various search strategies for light vector boson X in O(10) MeV mass range using J/Ψ associated channels at BESIII and Belle II: (i) J/Ψ → ηcX with 1010J/Ψs at BESIII, (ii) J/Ψ(ηc + X) + ℓℓ¯ production at Belle II, and (iii) J/Ψ + X with the displaced vertex in X → e+e− decay are analyzed and the future sensitivities at Belle II with 50 ab−1 luminosity are comprehensively...
Neutrino decay interaction with scalar majorons naturally arises from Standard Model extensions to model neutrino mass generation. The interaction if present during the CMB epoch has the potential to disrupt neutrino free streaming and hence the CMB anisotropy spectra. This has been previously studied as a cosmological constraint on neutrino lifetime. In this work, we model the decay...
The sigma8-tension of Planck data with weak lensing and redshift surveys is one of the main problems with the LambdaCDM model of cosmology. We show that the tension can be alleviated by introducing an interaction between dark matter and neutrinos. We model the interaction using a linear Boltzmann treatment, introducing a novel implementation that for the first time uses the full massive...
Minkowski functionals are set of descriptors used to describe the morphological structures of a field. CMB weak lensing, a powerful probe which imprinting projective information of matter distribution in the universe all the way back to the last scattering surface. With Minkowski functionals, one can reveal much more statistical features in the CMB lensing observations and eventually tighter...
Features in the CMB data have been discussed for a long time without striking evidence for or against them. Could the analysis of the data be the reason for this lack of evidence? Is there beyond LCDM physics hiding in the Planck CMB data? Applying a popular machine learning algorithm known as Bayesian Optimisation to Planck CMB can help us to find features in the data. Looking at modulations...
I will motivate why H0 tension may be indicative of a breakdown in the cosmological principle.
The origin of the flavor structure of three-generational quarks and leptons is one of the most significant mysteries. Modular flavor symmetry induced from the modular symmetry on a torus or some orbifolds is an attractive candidate of the origin of the flavor structure. In this talk, I will show that the modular flavor symmetry of three-generation modes on a torus orbifold with background...
We study local quark-hadron duality and its violation for the $D^0-\bar{D}^0$, $B^0_d-\bar{B}^0_d$ and $B^0_s-\bar{B}^0_s$ mixings in the 't Hooft model, offering a laboratory to test QCD based on two-dimensional spacetime in the large-$N_c$ limit. With the 't Hooft equation being numerically solved, the width difference is calculated as an exclusive sum over two-body decays. The obtained rate...
We find a new contribution in wave-packet scatterings, which has been overlooked in the standard formulation of S-matrix. As a concrete example, we consider a two-to-two scattering of light scalars 's' by another intermediate heavy scalar 'Phi', in the Gaussian wave-packet formalism: ss → Phi → ss. This contribution can be interpreted as an “in-time-boundary effect” of s for the corresponding...
We investigate long-lived particles (LLPs) produced in pair from neutral currents and decaying into a displaced electron plus two jets at the LHC, utilizing the proposed minimum ionizing particle timing detector at CMS. We study two benchmark models: the R-parity-violating supersymmetry with the lightest neutralinos and two different $U(1)$ extensions of the standard model with heavy neutral...
To realize first-order electroweak phase transition, it is necessary to generate a barrier in the thermal Higgs potential, which is usually triggered by scalar degree of freedom. We instead investigate phase transition patterns in pure fermion extensions of the standard model, and find that additional fermions with mass hierarchy and mixing could develop such barrier and realize strongly...
In this talk, we discuss whether a multi-step electroweak phase transition (EWPT) occurs in two Higgs doublet models (2HDMs). The EWPT is related to interesting phenomena such as baryogenesis and a gravitational wave from it. We examine parameter regions in CP-conserving 2HDMs and find certain areas where the multi-step EWPTs occur. In addition, we compute the Higgs trilinear coupling in the...
We numerically investigate the B + L violation process by performing three-dimensional lattice simulations of a unified scenario of first-order phase transitions and the sphaleron generation. The simulation results indicate that the Chern-Simons number changes along with the helical magnetic field production when the sphaleron decay occurs. Based on these numerical results, we then propose a...
The Georgi-Machacek model extends the standard model Higgs sector with one complex and one real isospin triplet scalar fields and preserves the custodial symmetry. Using the HEPfit, a Bayesian MCMC analysis package for particle physics, we scan for allowed parameter space under the constraints of Higgs productions and direct searches from LHC data, as well as various theory bounds. From the...
We study the feasibility of strong first-order electroweak phase transition in a degenerate-scalar scenario of a complex singlet extension of the Standard Model, in which a mass of an additional scalar is nearly degenerate with that of the Higgs boson, 125 GeV. This scenario is known to be free from strong constraints from dark matter direct detection experiments due to cancellations between...
We define a set of fully Lorentz-invariant wave packets and show that it spans the corre- sponding one-particle Hilbert subspace, and hence the whole Fock space as well, with a manifestly Lorentz-invariant completeness relation (resolution of identity). The position- momentum uncertainty relation for this Lorentz-invariant wave packet deviates from the ordinary Heisenberg uncertainty...
Gravity can be regarded as a consequence of local Lorentz (LL) symmetry, which is essential in defining a spinor field in curved spacetime. The gravitational action may admit a zero-field limit of the metric and vierbein at a certain ultraviolet cutoff scale such that the action becomes a linear realization of the LL symmetry. Consequently, only three types of term are allowed in the...
It has been known that when a charged fermion scatters off a monopole, the fermion in the s-wave component must flip its chirality. Because of this feature, if there are two or more flavors of massless fermions, any superposition of the fermion states cannot be the final state of the s-wave scattering as it is forbidden by conservation of the electric and flavor charges. The unitary evolution...
We present prospects for discovering dark matter scattering in gravitational wave detectors. The focus of this work is on light, particle dark matter with masses below 1 GeV/c2. We investigate how a potential signal compares to typical backgrounds like thermal and quantum noise, first in a simple toy model and then using KAGRA as a realistic example. That shows that for a discovery much...
We study the stochastic background of gravitational waves which accompany the sudden freeze-out of dark matter triggered by a cosmological first order phase transition that endows dark matter with mass. We consider models that produce the measured dark matter relic abundance via (1) bubble filtering, and (2) inflation and reheating, and show that gravitational waves from these mechanisms are...
Quasinormal modes (QNMs) of perturbed black holes have recently gained much interest because of their tight relations with the gravitational wave signals emitted during the post-merger phase of a binary black hole coalescence. One of the intriguing features of these modes is that they respect the no-hair theorem, and hence, they can be used to test black hole spacetimes and the underlying...
Unusual masses of the black holes being discovered by gravitational wave experiments pose fundamental questions about the origin of these black holes. More interestingly, black holes with masses smaller than the Chandrasekhar limit (~1.4 solar mass)? are essentially impossible to produce through any standard stellar evolution. Black holes of primordial origin, with fine-tuned parameters and...
In the early universe, primordial black holes (PBHs) can no longer be described by the simple Schwarzschild metric-- we need a metric which is locally surrounded by the cosmological fluid and asymptotically FLRW. It turns out that the phenomenology of PBHs is very sensitive to the choice of such a metric. In particular, the Thakurta metric stands out as perhaps the most justifiable metric for...
Primordial black holes (PBHs), possibly formed via gravitational collapse of large density perturbations in the very early universe, are one of the earliest proposed and viable dark matter (DM) candidates. Recent studies indicate that PBHs can make up a large or even entire fraction of the present day DM density for a wide range of masses. Ultralight PBHs in the mass range of 10^{15} - 10^{17}...
We study gamma-ray line signatures from electroweakly interacting non-abelian spin-1 dark matter (DM). In this model, Z_2-odd spin-1 particles including DM candidate have the SU(2)_L triplet-like features, and the Sommerfeld enhancement significantly affects the annihilation processes. The spin-1 DM system has additional partial wave contributions with the higher total spin angular...
The discovery of diffuse sub-PeV gamma-rays by the Tibet ASγ collaboration promises to revolutionize our understanding of the high-energy astrophysical universe. It has been shown that this data broadly agrees with prior theoretical expectations. In this talk, We will discuss the impact of this discovery on a well-motivated new physics scenario: PeV-scale decaying dark matter (DM). Considering...
The capture of Dark Matter in Neutron Stars has garnered considerable interest in recent years. This interest is driven by the prospect that the energy deposited by dark matter scattering can heat these objects to infra-red temperatures, which may soon be within reach of observations. In order to obtain reliable results from these searches, proper incorporation of the physics of Neutron stars...
Neutron star (NS) as the dark matter (DM) probe has gained a broad attention recently, either from heating due to DM annihilation or its stability under the presence of DM. In this work, we investigate spin-$1/2$ fermionic DM $\chi$ charged under the $U(1)_{X}$ in the dark sector. The massive gauge boson $V$ of $U(1)_{X}$ gauge group can be produced in NS via DM annihilation. The produced...
We discuss the capture of dark matter in white dwarfs (WD), the most abundant stellar remnants, as complimentary to terrestrial searches. We consider the capture of DM due to interactions with either ion or the degenerate electron component of WDs. For the discussion of the capture rate we account for the stellar structure, the star opacity, realistic nuclear form factors and temperature...
