arXiv subjects

Masako Iwasaki

Publications and source records attributed to Masako Iwasaki.

10 recordsLinked to original sources

arXiv2026

Future of Artificial Intelligence for Science in Japan 2024 Community Report

This white paper summarizes scientific challenges and AI/ML research opportunities identified through the FAIRS Japan 2024 unconference process. The discussion focuses on three major physics domains: accelerator physics, cosmology and astrophysics, and neutrino physics. Although each domain has distinct scientific goals and experimental constraints, several common technical themes emerge: high-dimensional reconstruction, fast and accurate simulation, uncertainty propagation, simulation-to-data mismatch, anomaly detection, real-time decision-making, and shared infrastructure.

hep-ph↗

arXiv2026

Search for Sub-GeV Axion-Like Particles at EBES Pilot Run Using 4 GeV Positron Beam at KEK LINAC

We report the results of a search for sub-GeV axion-like particles (ALPs) using pilot run data from the Electron Beam-dump Experiment at KEK LINAC Switching Yard 3 (EBES). The data were collected in December 2023 with a 4 GeV positron beam and correspond to $1.3\times10^{14}$ positrons on target. In the pilot run setup, a tungsten beam dump and a single PbO calorimeter were used. We consider ALP production via the Primakoff process induced by bremsstrahlung photons in the beam dump, followed by the decay $a\toγγ$. The background was estimated with a data-driven method, and a signal region was defined such that the expected background yield is below 0.1 events. No events were observed after unblinding. Upper limits at the 90% confidence level were derived in the ALP mass-coupling plane, extending the experimental coverage into a region of parameter space not explored by previous searches.

hep-ex↗

arXiv2022

Development of a Vertex Finding Algorithm using Recurrent Neural Network

Deep learning is a rapidly-evolving technology with possibility to significantly improve physics reach of collider experiments. In this study we developed a novel algorithm of vertex finding for future lepton colliders such as the International Linear Collider. We deploy two networks; one is simple fully-connected layers to look for vertex seeds from track pairs, and the other is a customized Recurrent Neural Network with an attention mechanism and an encoder-decoder structure to associate tracks to the vertex seeds. The performance of the vertex finder is compared with the standard ILC reconstruction algorithm.

physics.data-an↗

arXiv2001

The LCDROOT Analysis Package

The North American Linear Collider Detector group has developed simulation and analysis program packages. LCDROOT is one of the packages, and is based on ROOT and the C++ programing language to maximally benefit from object oriented programming techniques. LCDROOT is constantly improved and now has a new topological vertex finder, ZVTOP3. In this proceeding, the features of the LCDROOT simulation are briefly described.

hep-ex↗

arXiv2001

Study of Top-quark Production and Decay Vertices with LCD Fast Simulation

We report a study of top-quark reconstruction in $e^+e^- \rightarrow t\bar{t}$ events at a 500 GeV linear collider using the LCD Fast simulator. The initial study of top-quark anomalous couplings is also reported. The final states of 4 jets and lepton as well as 6 jets are used. Using the 4 jets and lepton final state, we estimate the preliminary sensitivities for form factors at the $γ/Z^0 t\bar{t}$ vertex. In the 6 jets reconstruction, we show abilities of the top-quark charge identification and the $c$-quark tagging in W decays.

hep-ex↗

arXiv2001

LCD ROOT Simulation and Analysis Tools

The North American Linear Collider Detector group has developed a simulation program package based on the ROOT system. The package consists of Fast simulation, the reconstruction of the Full simulated data, and physics analysis utilities.

hep-ex↗

arXiv2000

Measurements of Parity-Violation Parameters at SLD

We present direct measurements of the parity-violation parameters $A_b$, $A_c$, and $A_s$ at the $Z^0$ resonance with the SLD detector. The measurements are based on approximately 530k hadronic $Z^0$ events collected in 1993-98. Obtained results are $A_b = 0.914\pm0.024$ (SLD combined: preliminary), $A_c = 0.635\pm0.027$ (SLD combined: preliminary), and $A_s = 0.895\pm0.066(stat.)\pm 0.062(sys.)$.

hep-ex↗

arXiv1999

Study of top-quark reconstruction with LCD Fast Simulation

We report the study of top-quark reconstruction in $e^+e^- \to t\bar{t}$ events at a 500 GeV linear collider using the LCD Fast Simulator. The final states of 6 jets as well as 4 jets and lepton are used. In order to reconstruct the jets, the performance of charged and neutral cluster separation are studied. We compare top-quark reconstruction for the LCD Small and LCD Large detectors, including the effect of varying the calorimeter granularity.

hep-ex↗

arXiv1999

Measurements of $Z^0$ to Heavy-quark couplings at SLD

We present measurements of $Z^0$ to heavy-quark coupling electroweak parameters, $R_b$, $R_c$, and parity-violation parameter $A_c$, from SLD. The measurements are based on approximately 550k hadronic $Z^0$ events collected in 1993-98. Obtained preliminary results of $R_b$ and $R_c$ measurements are $R_b = 0.2159 \pm 0.0014 \pm 0.0014$ and $R_c = 0.1685 \pm 0.0047 \pm 0.0043$. In the $A_c$ measurement, we use four methods to determine the initial-quark charge: combined Kaon charge and Vertex charge, lepton, exclusively reconstructed D*, D-mesons, and a new method using inclusive soft-pion from D*. The preliminary results of these four methods were combined to give $A_c = 0.634 \pm 0.027$.

hep-ex↗

arXiv1995

Electron identification using the TOPAZ detector at TRISTAN

We present an electron-identification method using the time-projection chamber and the lead-glass calorimeter in the TOPAZ detector system. Using this method we have achieved good electron identification against hadron backgrounds over a wide momentum range in the hadronic events produced by both single-photon exchange and two-photon processes. Pion-rejection factors and electron efficiencies were 163 and 68.4\% for high-$P_T$ electrons and 137 and 42.7\% for low-$P_T$ electrons in the single-photon-exchange process, and 8600 and 36.0\% for the two-photon process, respectively.

hep-ex↗