Y. Yoshimura
A5025029678- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Neutrino Physics Research
- Particle Detector Development and Performance
- Nuclear physics research studies
- Medical Imaging Techniques and Applications
- Dark Matter and Cosmic Phenomena
- Radioactive Decay and Measurement Techniques
- Radiation Detection and Scintillator Technologies
- Atomic and Subatomic Physics Research
- Astrophysics and Cosmic Phenomena
- Atomic and Molecular Physics
- Black Holes and Theoretical Physics
- Radioactivity and Radon Measurements
- International Science and Diplomacy
- Congenital Heart Disease Studies
- Vascular Anomalies and Treatments
- Coronary Artery Anomalies
- Scientific Measurement and Uncertainty Evaluation
- Cold Atom Physics and Bose-Einstein Condensates
- Particle Accelerators and Free-Electron Lasers
- Computational Physics and Python Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Cardiac Valve Diseases and Treatments
Tokyo Metropolitan Children's Medical Center
2024
High Energy Accelerator Research Organization
1995-2022
Universidade de Santiago de Compostela
2015
Kyoto University
2007
Laboratoire de Physique Nucléaire et de Hautes Énergies
2003-2005
Institut National de Physique Nucléaire et de Physique des Particules
2003-2005
Sorbonne Université
2003-2005
Centre National de la Recherche Scientifique
2003-2005
Université Paris Cité
2003-2005
Budker Institute of Nuclear Physics
2002
Invariant mass spectra of e(+) e(-) pairs have been measured in 12 GeV p + A reactions to detect possible in-medium modification vector mesons. Copper and carbon targets are used study the nuclear-size dependence invariant distributions. significant excess on low-mass side phi meson peak is observed low betagamma(= beta/square root(1-beta(2))) region mesons (betagamma < 1.25) with copper targets. However, high betagamma > 1.25), spectral shapes well described by Breit-Wigner shape when...
Evidence of a heavy neutrino, $\nu_H$, in the $K^+\to\mu^+\nu_H$ decays was sought using E949 experimental data with an exposure $1.70\times 10^{12}$ stopped kaons. With major background from radiative $K^+\to\mu^+\nu_\mu\gamma$ decay understood and suppressed, upper limits (90% C.L.) on neutrino mixing matrix element between muon $|U_{\mu H}|^2$, were set at level $10^{-7}$ to $10^{-9}$ for mass region 175 300 MeV/$c^2$.
The goal of the DIRAC experiment at CERN (PS212) is to measure $\pi^+\pi^-$ atom lifetime with 10% precision. Such a measurement would yield precision 5% on value $S$-wave $\pi\pi$ scattering lengths combination $|a_0-a_2|$. Based part collected data we present first result lifetime, $\tau=[2.91 ^{+0.49}_{-0.62}]\times 10^{-15}$ s, and discuss major systematic errors. This corresponds $|a_0-a_2|=0.264 ^{+0.033}_{-0.020} m_{\pi}^{-1}$.
We searched for possible signatures of top-quark production in 508 ${e}^{+}{e}^{\ensuremath{-}}$ hadronic annihilation events collected at $\sqrt{s}=52$ GeV by the TOPAZ detector KEK collider TRISTAN. The observed cross section and shape are consistent with standard-model predictions without top quarks. A lower limit (95% confidence level) on mass lightest meson is set 25.8 GeV.
Evidence of the $K^+\to\mu^+\nu\bar\nu\nu$ decay was searched for using E949 experimental data with an exposure $1.70\times 10^{12}$ stopped kaons. The sample is dominated by backgrond process $K^+\to\mu^+\nu_\mu\gamma$. An upper limit on rate $\Gamma(K^+\to\mu^+\nu\bar\nu\nu)< 2.4\times 10^{-6}\Gamma(K^+\to all)$ at 90% confidence level set assuming Standard Model muon spectrum. are presented in such a way as to allow calculation rates any assumed $\mu^+$
We present evidence for the first observation of electromagnetically bound $\pi^\pm K^\mp$-pairs ($\pi K$-atoms) with DIRAC experiment at CERN-PS. The $\pi K$-atoms are produced by 24 GeV/c proton beam in a thin Pt-target and $\pi^\pm$ $K^\mp$-mesons from atom dissociation analyzed two-arm magnetic spectrometer. observed enhancement low relative momentum corresponds to production 173 $\pm$ 54 K$-atoms. mean life is related s-wave K$-scattering lengths, measurement which goal experiment. From...
After observing and investigating the double-exotic (a atom is a bound system, in which both oppositely charged components are unstable particles like μ,π,K,…) π+π− with ground state lifetime τ of about 3×10−15 s, upgraded DIRAC experiment at CERN PS accelerator observes for first time long-lived states same lifetimes 10−11 s more. The number characteristic pion pairs resulting from breakup (ionisation) atoms amounts to 436±61, corresponding signal-to-error ratio better than 7 standard...
After having announced the statistically significant observation (5.6~$\sigma$) of new exotic $\pi K$ atom, DIRAC experiment at CERN proton synchrotron presents measurement corresponding atom lifetime, based on full data sample: $\tau = (5.5^{+5.0}_{-2.8}) \cdot 10^{-15}s$. By means a precise relation ($<1\%$) between lifetime and scattering length, following value for S-wave isospin-odd length $a_0^{-}~=~\frac{1}{3}(a_{1/2}-a_{3/2})$ has been derived: $\left|a_0^-\right|...
We present results on inclusive study of particle production ratios in 405-GeV/c $\mathrm{pp}$ interactions from a Fermilab experiment using the 30-in. hydrogen bubble chamber. Single- and double-pion $\frac{{\ensuremath{\pi}}^{+}}{{\ensuremath{\pi}}^{\ensuremath{-}}}$, $\frac{{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}}{{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}}$,...
We have searched for new sequential heavy leptons L± in e+e− collisions at √s =52 GeV using the TOPAZ detector KEK storage ring TRISTAN. In collected data with an integrated luminosity of 3.6 pb−1, no evidence production has been observed. A lower mass limit is determined to be 25.5 GeV/c2 95% confidence level.Received 18 November 1987DOI:https://doi.org/10.1103/PhysRevD.37.1339©1988 American Physical Society
In this work the Coulomb effects (Coulomb correlations) in $\pi^+\pi^-$ pairs produced p + Ni collisions at 24 GeV/$c$, are studied using experimental pair distributions $Q$, relative momentum center of mass system (c.m.s), and its projections $Q_L$ (longitudinal component) $Q_t$ (transverse to direction laboratory (l.s.). The $Q_L$, {\sl pairs} c.m.s. have been simulated assuming they described by phase space modified known point-like correlation function $A_C(Q)$, corrected for small due...
In this work, the Coulomb effects (Coulomb correlations) in <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msup><a:mi>π</a:mi><a:mo>+</a:mo></a:msup><a:msup><a:mi>π</a:mi><a:mo>−</a:mo></a:msup></a:math> pairs produced <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:mi mathvariant="normal">p</c:mi><c:mo>+</c:mo><c:mi>Ni</c:mi></c:mrow></c:math> collisions at <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"...