We calculate the cross section for the process $\mu^-\mu^+\to \nu_\mu\bar{\nu}_\mu t\bar{t}H$ with complex top Yukawa coupling, which can be obtained by adding a gauge invariant dimension-6 operator to the Standard Model (SM) Lagrangian. The Feynman-Diagram (FD) gauge and the unitary (U) gauge amplitudes give exactly the same cross section, and subtle gauge theory cancellation among diagrams...
The Higgs mass as one of the fundamental parameters in the Standard Model has been already measured pretty well by the data collected so far at the LHC. However in some cases of looking for small deviations from the SM, current precision or projection of the Higgs mass measurement at the LHC or HL-LHC may not be good enough. One prominent example is for the SM prediction of the Higgs partial...
In the upcoming generation of collider experiments, such as the proposed Linear Collider Higgs Factory, precise measurement of particle flow (PF) is pivotal for enhancing the energy resolution of jets, which consist of numerous hadrons observed in the final state. To achieve this, we focus on equipping fine-segmented electromagnetic calorimeters with high-precision time measurement...
The AWAKE project at CERN makes use of plasma to transfer energy from the SPS proton beam to a short witness beam of electrons. We here give an overview of the project, from the exploitation of beam-plasma instabilities to generate large accelerating fields, to the next stages of the project, which will demonstrate sustained accelerating gradients and control of the witness bunch emittance. ...
For the success of the International Linear Collider (ILC), it is crucial for the project to be accepted and integrated within the local communities. This requires close cooperation between the ILC Laboratory and the surrounding municipalities to develop "next-generation city planning initiatives triggered by the ILC" that bring extensive and diverse value to the region. Furthermore, it is...
Dark Matter being electrically neutral does not participate in electromagnetic interactions at leading order. However, we discuss here fermionic dark matter (DM) with permanent magnetic and electric dipole moment that interacts electromagnetically with photons at loop-level through a dimension-5 operator. We discuss the search prospect of the dark matter at the proposed International Linear...
The BELLA Center has been pursuing laser and laser-plasma accelerator (LPA) research for high energy physics. One of the ultimate goals is to provide a building block for future linear colliders. At the flagship 1-Hz 1-PW laser facility, the development of a 10-GeV class LPA module is ongoing, and such modules in series are envisioned as the path to a high energy collider at TeV energies and...
Neutrino oscillation is a phenomenon where the neutrino oscillates between its flavor states while propagating. This comes as a result of neutrino flavor states being eigenstates of the weak interaction Hamiltonian but not of the propagation Hamiltonian. The latter possesses different eigenstates called the mass states. The change of basis between these states is described by a unitary matrix...
The ILC is currently proposed to be running at 250 GeV at the initial stage, based on the fact that the cross section of the leading Higgs production channel (ZH) peaks at more or less 250 GeV. Due to the effects of beamstraglung and initial state radiation which shift the effective center of mass energies, the more optimal collision energy has not been known yet. First, we will carry out...
Transformers are one of the recent big achievements of machine learning, which enables realistic communication on natural language processing such as ChatGPT, as well as being applied to many other fields such as image processing. The basic concept of a Transformer is to learn relation between two objects by an attention mechanism. This structure is especially efficient with large input...
The existence of dark matter is currently one of the strong motivations for beyond the standard model. We consider the model of the composite dark matter. Our model assumes that meson-like dark matter (call it dark mesons) is a bounded state of dark quark ($\psi$) and anti-dark quark ($\bar{\psi}$) pairs, where $\psi$ and $\bar{\psi}$ have a confining force at work. Confining force is based on...
Recently, CMS group shows the data of the multi-muon signals. Two years ago, possible excess of dimuon signal was reported in Moriond 2023. This year, four muon signal is reported in Moriond 2024. Both data indicates the excess level of $2\sigma$. It is possible that these excesses are from Hidden sector physics. We consider the way to account for the excesses by setting SM and 2 dark sector....
We have developed the energy calibration method by using the machine learning for the ILC EM calorimeter (ECAL), a sampling calorimeter consisting with Silicon-Tungsten layers.
In this method, we use deep neural network (DNN) to get the energy of the incident particle (energy calibration), as a regression problem,
to improve the energy calibration resolution of ECAL.
We have developed the...
The International Linear Collider (ILC) is an electron-positron linear collider to explore physics beyond the Standard Model of particle physics in the center of mass energy of 250 GeV to 1 TeV.
In the TDR, to make a positron, a helical undulator of more than 150 m long will be planning to insert in the main electron linac.
And in parallel, to mitigate the risks associated with the...
We study Majorana Right Handed Neutrinos (RHN) production at ILC. Various extensions of the SM aim to explain the origin of the tiny neutrino mass; one of them is by the introduction of RHN. When we assume that RHN is a Majorana particle, RHN pair production is allowed in e−e+ collisions. We focus on this RHN pair production based on a minimal U(1)B−L model. A distinctive signature is a pair...
Superconducting radio-frequency cavities made of pure bulk niobium (Nb) is an essential tool in modern accelerator science and technology. Nb superconducting radio-frequency (SRF) cavities can extremely efficiently accelerate charged particles. At the High Energy Accelerator Research Organization(KEK), Tesla-shaped 1.3 GHz Nb SRF cavities has been developed for next-generation accelerator...
We study the W pair production at future lepton colliders. For the production of longitudinally polarized W bosons, it is well known that large gauge cancellation occurs among the amplitudes, especially at high energies, because of the energy growth of each amplitude. In this study, we adopt a recently-proposed gauge fixing, so-called Feynman-Diagram gauge and revisit the process to show such...
Minimal dark matter is one of the most motivated dark matter candidates, and many analyses at collider experiments for this model have been discussed. In our work, we considered the search for minimal dark matter at future high-energy lepton collider experiments. We found that the indirect search, which measures the quantum correction to the muon elastic scattering, is much more sensitive than...
