arXiv subjects

Koji Tsumura

Publications and source records attributed to Koji Tsumura.

At least 19 recordsLinked to original sources

arXiv2026

Two component pseudo-Nambu-Goldstone-boson dark matter

We study a two-component pseudo-Nambu-Goldstone-boson (pNGB) dark matter (DM) model motivated by boosted dark matter (BDM). The model is based on a complex scalar field charged under a dark $\text{U}(1)_V$ gauge symmetry, with a softly broken global $\text{SU}(3)_g$ symmetry that is spontaneously broken. The pNGB nature suppresses DM--Nucleon scattering, while the residual $\text{U}(1)_3 \times \text{U}(1)_{T_0}$ symmetry automatically stabilizes the two pNGB DM candidates and allows conversion of the heavier component into the lighter one. A central point is that the heavier or light component hierarchy is controlled by the two independent soft-breaking parameters that split the pNGB multiplet, so an abundant heavier component required for BDM can be obtained without introducing ad hoc hierarchies among independent portal coupling tuned to enable effective conversion. We analyze the relic abundance together with the constraints considered in this work, including Higgs invisible decays and perturbative unitarity, classify the coupled freeze-out dynamics, and assess the resulting BDM scattering cross section and flux.

hep-ph↗

arXiv2025

Pseudo-Nambu-Goldstone-boson Dark Matter from Three Complex Scalars

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 $\mathrm{U}(1)$ 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 $\mathrm{U}(1)_V$ gauge symmetry together with a permutative exchange symmetry among three scalars. These features naturally suppress the dark matter--nucleon scattering cross section by its Nambu-Goldstone boson nature. In addition to conventional annihilation channels, the $\mathbb{Z}_3$ structure allows semi-annihilation processes, playing a crucial role in setting the relic abundance.We analyze theoretical and experimental constraints, including relic abundance, Higgs invisible decays, and perturbative unitarity, and evaluate the elastic scattering cross section for boosted dark matter.

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arXiv2024

New Constraints on Gauged U(1)$_{L_μ-L_τ}$ Models via $Z-Z'$ Mixing

It is known that the model based on U(1)$_{L_μ-L_τ}$ gauge symmetry can explain not only the discrepancy between the measured value of muon $g-2$ and the theoretical prediction, but also the structure of the neutrino mass and mixings. We revisit the analysis of the mass matrix structure in the minimal U(1)$_{L_μ-L_τ}$ models based on the latest experimental result, where the minimal stands for the symmetry breaking caused only by a single scalar field. We find that the model called type ${\bf 2}_{+1}$, where an SU(2)$_L$ doublet scalar $Φ_{+1}$ with the U(1)$_{L_μ- L_τ}$ charge $+1$ and the hypercharge $+1/2$, predicts the $\bf B_3$ texture and is marginally acceptable under the current neutrino oscillation data and cosmological observation. When the U(1)$_{L_μ- L_τ}$ gauge symmetry is broken by the vacuum expectation value of the standard model non-singlet representation such as $Φ_{+1}$, there are additional contributions to the flavor-changing meson decay process and atomic parity violation via the $Z-Z'$ mixing. We newly evaluate the model-dependent constraints on the model and conclude that the type ${\bf 2}_{+1}$ model is robustly ruled out. The model is extended to have an additional vacuum expectation value of a standard model singlet scalar in order to avoid the stringent constraint from the flavor-changing meson decay. Finally, we find the allowed range of the ratio of these vacuum expectation values.

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arXiv2024

Nambu-Goldstone Modes in Magnetized $T^{2n}$ Extra Dimensions

We consider a $U(1)$ gauge theory on $M^4\times T^4$ with background magnetic fluxes. We show that a theory including arbitrary fluxes can always be studied in a theory involving only diagonal fluxes by appropriate coordinate transformations. It is found that the number of independent magnetic fluxes is equal to the rank of the classical value of the field strength matrix, ${\rm rank}\langle F\rangle$. The number of massless zero modes induced from extra components of higher-dimensional gauge field (Wilson-line scalar field), is also determined by ${\rm rank}\langle F\rangle$. We explicitly confirm that the quantum corrections due to the matter fermion to the squared mass of Wilson-line scalar field cancel out at one-loop level. For this purpose, we derive the fermion mass spectrum on $M^4\times T^4$ with arbitrary fluxes. By taking the flux diagonal basis, creation and annihilation operators for Kaluza-Klein quantum numbers are defined appropriately. Our results are easily generalized to the case of $M^4\times T^{2n}~(n\geq3)$.

hep-th↗

arXiv2024

A model of pseudo-Nambu-Goldstone dark matter with two complex scalars

Pseudo-Nambu-Goldstone (pNG) dark matter (DM) is a promising DM candidate and able to explain the measured DM abundance by the thermal freeze-out mechanism evading the stringent bound from DM direct detection experiments. We propose a new model providing a pNG DM by introducing two Standard-Model-singlet complex scalars with the same charges of a dark $U(1)$ gauge symmetry. They are also charged under a $U(1)$ global symmetry corresponding to their relative phase rotations, which is explicitly broken by a soft-breaking term in the scalar potential. The both $U(1)$ symmetries are spontaneously broken by their vacuum expectation values, giving rise to one real pNG boson. We also introduce a discrete $\mathbb{Z}_2$ symmetry exchanging the two scalars to stabilize the pNG boson as DM. It is shown that this model reproduces the DM abundance consistently with the current bound from the direct detection experiments. The model has a gauge kinetic mixing between the dark and $U(1)_Y$ gauge fields, which allows the dark gauge boson to decay even with a relatively light mass and prevents it from being an additional DM component. The Landau pole is avoided thanks to the small gauge coupling constant. In addition, a DM pair dominantly annihilates into a pair of the dark gauge bosons if the gauge boson mass is lighter than the DM mass, and thus its cross section has significantly different parameter dependence from other pNG DM models. We also calculate the DM-nucleon scattering cross section at the loop level. It turns out that it is necessary to probe region covered by the neutrino fog in order to test this model.

hep-ph↗

arXiv2024

Pseudo-Nambu-Goldstone Dark Matter in $SU(7)$ Grand Unification

We propose a grand unified theory (GUT) pseudo-Nambu-Goldstone boson (pNGB) dark matter (DM) model based on $SU(7)$ gauge symmetry. In the GUT model, the Standard Model (SM) gauge symmetry $G_{\rm SM} := SU(3)_C\times SU(2)_L\times U(1)_Y$ and the ``dark'' gauge symmetry $SU(2)_D$ are unified, where the $SU(2)_D$ symmetry plays an important role in the stability of DM. The unification of SM fermions and dark sector fermions is partially realized. The gauge symmetry $SU(7)$ is spontaneously broken to $SU(5)\times SU(2)\times U(1)$ gauge symmetry at the GUT scale by the nonvanishing vacuum expectation values of an $SU(7)$ adjoint scalar field. The symmetry is further broken to $G_{\rm SM}\times SU(2)_D$ at an intermediate scale. Furthermore, the $SU(2)_D$ symmetry is broken by the $SU(2)_D$ doublet and triplet scalar fields at the TeV scale. In the pNGB DM model based on $G_{\rm SM}\times SU(2)_D$, the residual global $U(1)_V$ dark custodial symmetry guarantees DM stability. On the other hand, in the $SU(7)$ pNGB DM model, this global symmetry is explicitly broken by the Yukawa interaction and the effective Majorana mass terms. To maintain $U(1)_V$ symmetry and thus the DM stability, we need to tune Yukawa coupling constants and cubic scalar couplings at high accuracy. We find that the allowed DM mass region is quite restricted as the gauge coupling constant of $SU(2)_D$ is determined by the condition of the gauge coupling unification. To satisfy gauge coupling unification and the current experimental constraint on proton lifetime, we find that three generations of $SU(3)_C$ adjoint fermions and another three generations of $SU(2)_L$ adjoint fermions with the intermediate mass scale are required. We also find that there is no other solution to satisfy simultaneously the gauge coupling unification and the proton decay constraint if one assumes the other symmetry breaking schemes.

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arXiv2022

Pseudo-Nambu-Goldstone Dark Matter from Non-Abelian Gauge Symmetry

We propose a pseudo-Nambu-Goldstone boson (pNGB) dark matter (DM) model based on an additional non-Abelian gauge symmetry $SU(2)_D$. The gauge symmetry $SU(2)_D$ is spontaneously broken to a global custodial symmetry $U(1)_V$ via the nonvanishing vacuum expectation values of $SU(2)_D$ doublet and triplet scalar fields. Due to the exact global symmetry $U(1)_V$, the lightest $U(1)_V$ charged particle becomes stable. We assume that the lightest charged particle in the model is the charged complex pNGB, which we regard as DM. It avoids the strong constraints from current DM direct detection experiments due to the property of NGB. We find that the measured energy density of DM can be reproduced when the DM mass is larger than the half of the Higgs mass, where the lower limit generally comes from the constraint of DM invisible decay and the upper limit from DM direct detection experiments depends on the model parameters.

hep-ph↗

arXiv2022

Scalar Dark Matter with a $μτ$ Flavored Mediator

We study a renormalizable scalar singlet dark matter model based on $Z_4$ lepton flavor symmetry. A $μτ$-philic scalar doublet is introduced to explain the discrepancy between the experimental value and the theoretical prediction of the muon anomalous magnetic moment. At the same time, these flavored scalars play the role of a mediator which connects dark matter and standard model particles. The observed relic abundance of the dark matter is easily maintained while satisfying the current severe constraints on the dark matter from various experiments and observations thanks to the flavor off-diagonal interactions of scalar mediators. We also explore the possibility of dark matter direct detection through the one-loop process.

hep-ph↗

arXiv2021

Baryon number non-conservation as Peccei-Quinn mechanism

Baryon number is an accidental symmetry in the standard model, while Peccei-Quinn symmetry is hypothetical symmetry which is introduced to solve the strong CP problem. We study the possible connections between Peccei-Quinn symmetry and baryon number symmetry. In this framework, an axion is identified as the Nambu-Goldstone boson of baryon number violation. As a result, characteristic baryon number violating processes are predicted. We developed the general method to determine the baryon number and lepton number of new scalar in the axion model.

hep-ph↗

arXiv2021

Pseudo-Nambu-Goldstone Dark Matter Model Inspired by Grand Unification

A pseudo-Nambu-Goldstone boson (pNGB) is an attractive candidate for dark matter (DM) due to the simple evasion of the current severe limits of DM direct detection experiments. One of the pNGB DM models has been proposed based on a {\it gauged} $U(1)_{B-L}$ symmetry. The pNGB has long enough lifetime to be a DM and thermal relic abundance of pNGB DM can be fit with the observed value against the constraints on the DM decays from the cosmic-ray observations. The pNGB DM model can be embedded into an $SO(10)$ pNGB DM model in the framework of an $SO(10)$ grand unified theory, whose $SO(10)$ is broken to the Pati-Salam gauge group at the unified scale, and further to the Standard Model gauge group at the intermediate scale. Unlike the previous pNGB DM model, the parameters such as the gauge coupling constants of $U(1)_{B-L}$, the kinetic mixing parameter of between $U(1)_Y$ and $U(1)_{B-L}$ are determined by solving the renormalization group equations for gauge coupling constants with appropriate matching conditions. From the constraints of the DM lifetime and gamma-ray observations, the pNGB DM mass must be less than $\mathcal{O}(100)$$\,$GeV. We find that the thermal relic abundance can be consistent with all the constraints when the DM mass is close to half of the CP even Higg masses.

hep-ph↗

arXiv2021

Scalar and fermion on-shell amplitudes in generalized Higgs effective field theory

Beyond standard model (BSM) particles should be included in effective field theory in order to compute the scattering amplitudes involving these extra particles. We formulate an extension of Higgs effective field theory which contains arbitrary number of scalar and fermion fields with arbitrary electric and chromoelectric charges. The BSM Higgs sector is described by using the non-linear sigma model in a manner consistent with the spontaneous electroweak symmetry breaking. The chiral order counting rule is arranged consistently with the loop expansion. The leading order Lagrangian is organized in accord with the chiral order counting rule. We use a geometrical language to describe the particle interactions. The parametrization redundancy in the effective Lagrangian is resolved by describing the on-shell scattering amplitudes only with the covariant quantities in the scalar/fermion field space. We introduce a useful coordinate (normal coordinate), which simplifies the computations of the on-shell amplitudes significantly. We show the high energy behaviors of the scattering amplitudes determine the "curvature tensors" in the scalar/fermion field space. The massive spinor-wavefunction formalism is shown to be useful in the computations of on-shell helicity amplitudes.

hep-ph↗

arXiv2021

Search for U(1)$_{L_μ-L_τ}$ charged Dark Matter with neutrino telescope

We study a simple Dirac fermion dark matter model in U(1)$_{L_μ-L_τ}$ theory. The new light gauge boson $X$ plays important roles in both dark matter physics and the explanation for the muon $g-2$ anomaly. The observed dark matter relic density is realized by a large U(1)$_{L_μ-L_τ}$ charge without introducing a resonance effect of the $X$ boson. As a by-product of the model, characteristic neutrino signatures from sub-GeV dark matter $ψ$ are predicted depending on the mass spectrum. We formulate the analysis of $ψ\barψ\to ν\barν$, and of $ψ\barψ\to XX$ followed by $X\toν\barν$, in a model independent way. The energy spectrum of neutrinos in the former process is monochromatic while in the latter process is bowl-shape. We also evaluate sensitivity at Super-Kamiokande and future Hyper-Kamiokande detectors. The analysis is finally applied to the U(1)$_{L_μ-L_τ}$ dark matter model.

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arXiv2020

Distributed Stabilization by Probability Control for Deterministic-Stochastic Large Scale Systems : Dissipativity Approach

By using dissipativity approach, we establish the stability condition for the feedback connection of a deterministic dynamical system $Σ$ and a stochastic memoryless map $Ψ$. After that, we extend the result to the class of large scale systems in which: $Σ$ consists of many sub-systems; and $Ψ$ consists of many "stochastic actuators" and "probability controllers" that control the actuator's output events. We will demonstrate the proposed approach by showing the design procedures to globally stabilize the manufacturing systems while locally balance the stock levels in any production process.

eess.SY↗

arXiv2020

Scalegenesis and fermionic dark matters in the flatland scenario

We propose an extension of the standard model with Majorana-type fermionic dark matters based on the flatland scenario where all scalar coupling constants, including scalar mass terms, vanish at the Planck scale, i.e. the scalar potential is flat above the Planck scale. This scenario could be compatible with the asymptotic safety paradigm for quantum gravity. We search the parameter space so that the model reproduces the observed values such as the Higgs mass, the electroweak vacuum and the relic abundance of dark matter. We also investigate the spin-independent elastic cross section for the Majorana fermions and a nucleon. It is shown that the Majorana fermions as dark matter candidates could be tested by dark matter direct detection experiments such as XENON, LUX and PandaX-II. We demonstrate that within the minimal setup compatible with the flatland scenario at the Planck scale or asymptotically safe quantum gravity, the extended model could have a strong predictability.

hep-ph↗

arXiv2020

Pseudo-Nambu-Goldstone dark matter from gauged $U(1)_{B-L}$ symmetry

A pseudo-Nambu-Goldstone boson (pNGB) is an attractive candidate for dark matter since the current severe limits of dark matter direct detection experiments are naturally evaded by its nature. We construct a model with pNGB dark matter based on a {\it gauged} $U(1)_{B-L}$ symmetry, where no ad-hoc global symmetry is assumed. The model keeps natural suppression mechanism for the dark matter direct detection cross section. On the other hand, the pNGB can decay through the new high scale suppressed operators. We show that the pNGB has long enough lifetime to be a dark matter in the wide range of the parameter space of the model. The thermal relic abundance of pNGB dark matter can be fit with the observed value against the constraints on the dark matter decays from the cosmic-ray observations.

hep-ph↗

arXiv2019

QED background against atomic neutrino process with initial spatial phase

Atomic deexcitation emitting a neutrino pair and a photon is expected to provide a novel method of neutrino physics if it is enhanced by quantum coherence in a macroscopic target. However, the same enhancement mechanism may also lead to a serious problem of enhanced QED background process. We show that the QED background can be suppressed enough in the photonic crystal waveguide by using the spatial phase that is imprinted in the process of initial coherence generation in the target at excitation.

hep-ph↗

arXiv2019

Symmetry and geometry in generalized Higgs effective field theory -- Finiteness of oblique corrections v.s. perturbative unitarity

We formulate a generalization of Higgs effective field theory (HEFT) including arbitrary number of extra neutral and charged Higgs bosons (generalized HEFT, GHEFT) to describe non-minimal electroweak symmetry breaking models. Using the geometrical form of the GHEFT Lagrangian, which can be regarded as a nonlinear sigma model on a scalar manifold, it is shown that the scalar boson scattering amplitudes are described in terms of the Riemann curvature tensor (geometry) of the scalar manifold and the covariant derivatives of the potential. The coefficients of the one-loop divergent terms in the oblique correction parameters S and U can also be written in terms of the Killing vectors (symmetry) and the Riemann curvature tensor (geometry). It is found that perturbative unitarity of the scattering amplitudes involving the Higgs bosons and the longitudinal gauge bosons demands the flatness of the scalar manifold. The relationship between the finiteness of the electroweak oblique corrections and perturbative unitarity of the scattering amplitudes is also clarified in this language: we verify that once the tree-level unitarity is ensured, then the one-loop finiteness of the oblique correction parameters S and U is automatically guaranteed.

hep-ph↗

arXiv2019

A $μ$-$τ$-philic scalar doublet under $Z_n$ flavor symmetry

We propose a minimal model which accommodates the long-standing anomaly of muon magnetic moment based on abelian discrete flavor symmetries. The standard model is extended by scalar doublets charged under a $Z_n$ lepton flavor symmetry. In these models, a large contribution to the muon magnetic moment can be obtained by the chirality enhancement from new scalar mediated diagrams without conflicting with the flavor symmetry. Thanks to the lepton flavor symmetry, these models automatically forbid lepton flavor violation. The minimal model is based on $Z_4$ symmetry with only one extra scalar doublet. In this model, we show that the parameter space favored by the muon $g-2$ can easily be consistent with experimental constraints and theoretical bounds such as the electroweak precision tests, lepton universality, potential stability condition and triviality bound as well as the LHC direct search mass bound. The new contributions to the muon electric dipole moment and the Higgs decay into $γγ$ can be indirect signals of the model.

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