A5038978270- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Muon and positron interactions and applications
- Quantum Chromodynamics and Particle Interactions
- Particle accelerators and beam dynamics
- Particle Detector Development and Performance
- Superconducting Materials and Applications
- Radiation Detection and Scintillator Technologies
- Particle Accelerators and Free-Electron Lasers
- High-Energy Particle Collisions Research
- Atomic and Subatomic Physics Research
- Computational Physics and Python Applications
- Nuclear physics research studies
- Physics of Superconductivity and Magnetism
- Nuclear Physics and Applications
- Black Holes and Theoretical Physics
- Advanced NMR Techniques and Applications
- Advanced Condensed Matter Physics
- Cosmology and Gravitation Theories
- Radiation Therapy and Dosimetry
- Gamma-ray bursts and supernovae
- Medical Imaging Techniques and Applications
- International Science and Diplomacy
Osaka University
2016-2025
The University of Tokyo
1988-2024
Osaka University of Tourism
2023
RIKEN
2023
University of Fukui
2002-2022
High Energy Accelerator Research Organization
2002-2020
RIKEN Center for Computational Science
2019-2020
Université Clermont Auvergne
2019-2020
Toneyama National Hospital
2010-2020
Naval Research Laboratory Information Technology Division
2019-2020
We present measurements of nu_mu disappearance in K2K, the KEK to Kamioka long-baseline neutrino oscillation experiment. One hundred and twelve beam-originated events are observed fiducial volume Super-Kamiokande with an expectation 158.1^{+9.2}_{-8.6} without oscillation. A distortion energy spectrum is also seen 58 single-ring muon-like reconstructed energies. The probability that observations explained by for no 0.0015% (4.3sigma). In a two flavor scenario, allowed Delta m^2 region at...
This article reviews the current theoretical and experimental status of field muon decay its potential to search for new physics beyond standard model. The importance rare processes with lepton flavor violation is highly stressed, together precision measurements normal decay. Recent up-to-date motivations based on supersymmetric models, in particular grand unified theories, are described along other models. Future prospects experiments sources high intensity further progress this also discussed.
We present results for ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ oscillation in the KEK to Kamioka (K2K) long-baseline neutrino experiment. K2K uses an accelerator-produced beam with a mean energy of 1.3 GeV directed at Super-Kamiokande detector. observed energy-dependent disappearance ${\ensuremath{\nu}}_{\ensuremath{\mu}}$, which we presume have oscillated ${\ensuremath{\nu}}_{\ensuremath{\tau}}$. The probability that would observe these if there is no 0.0050% ($4.0\ensuremath{\sigma}$).
We present a search for non-zero theta_{13} and deviations of sin^2 theta_{23} from 0.5 in the oscillations atmospheric neutrino data Super-Kamiokande -I, -II, -III. No distortions flux consistent with are found both mass hierarchy hypotheses agreement data. The best fit at Delta m^2 = 2.1 x 10^-3 eV^2, 0.0, =0.5. In normal (inverted) constrained one-dimensional 90% C.L. to < 0.04 (0.09) 1.9 (1.7) 2.6 (2.7) eV^2. mixing angle is within 0.407 <= 0.583
Super-Kamiokande (SK) can search for weakly interacting massive particles (WIMPs) by detecting neutrinos produced from WIMP annihilations occurring inside the Sun. In this analysis, we include neutrino events with interaction vertices in detector addition to upward-going muons surrounding rock. Compared previous result, which used only, signal acceptances light (few−GeV/c2−200−GeV/c2) WIMPs are significantly increased. We fit 3903 days of SK data contribution annihilation found no...
The status of the research on muon colliders is discussed and plans are outlined for future theoretical experimental studies. Besides continued work parameters a 3-4 0.5 TeV center-of-mass (CoM) energy collider, many studies now concentrating machine near 0.1 that could be factory s-channel production Higgs particles. We discuss various components in such colliders, starting from proton accelerator needed to generate pions heavy-Z target proceeding through phase rotation decay ($\pi \to \mu...
The conclusions of the Physics Working Group international scoping study a future Neutrino Factory and super-beam facility (the ISS) are presented. ISS was carried by community between NuFact05, 7th International Workshop on Factories Superbeams, Laboratori Nazionali di Frascati, Rome, June 21-26, 2005) NuFact06 (Ivine, California, 24{30 August 2006). physics case for an extensive experimental programme to understand properties neutrino is presented role high-precision measurements...
Positive-muon spin-rotation and -relaxation measurements of the oxygen-deficient perovskite ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{\mathrm{x}}$ have revealed local antiferromagnetic order for 6.0\ensuremath{\lesssim}x\ensuremath{\lesssim}6.4 with a N\'eel temperature ${T}_{\mathrm{N}}$ that decreases rapidly increasing oxygen content x. For slowly annealed samples 6.35\ensuremath{\lesssim}x\ensuremath{\lesssim}6.5 superconducting transition ${T}_{c}$ increases smoothly x from...
A new Super-Kamiokande (SK) search for Supernova Relic Neutrinos (SRNs) was conducted using 2853 live days of data. Sensitivity is now greatly improved compared to the 2003 SK result, which placed a flux limit near many theoretical predictions. This more detailed analysis includes variety improvements such as increased efficiency, lower energy threshold, and an expanded data set. New combined upper limits on SRN are between 2.8 3.0 nu_e cm^-2 s^-1 > 16 MeV total positron (17.3 E_nu).
A new measurement of the ${\mathrm{\ensuremath{\pi}}}^{+}$\ensuremath{\rightarrow}${\mathit{e}}^{+}$\ensuremath{\nu} branching ratio gives ${\mathit{R}}_{\mathrm{\ensuremath{\pi}}\mathit{e}\ensuremath{\nu}}$=\ensuremath{\Gamma}(\ensuremath{\pi}\ensuremath{\rightarrow}e\ensuremath{\nu}+\ensuremath{\pi}\ensuremath{\rightarrow}e\ensuremath{\nu}\ensuremath{\gamma})/\ensuremath{\Gamma}...
The weak nucleon axial-vector form factor for quasi-elastic interactions is determined using neutrino interaction data from the K2K Scintillating Fiber detector in beam at KEK. More than 12,000 events are analyzed, of which half charged-current nu-mu n to mu- p occurring primarily oxygen nuclei. We use a relativistic Fermi gas model and assume approximately dipole with one parameter, axial vector mass M_A, fit shape distribution square momentum transfer nucleus. Our best result M_A = 1.20...
The magnetic properties of four different phases the YBa 2 Cu 3 O x system, including famous 90 K superconductor, have been probed by positive muon spin relaxation method (µ + SR). oxygen-deficient tetragonal insulating phase ( ∼6.2) was found to be magnetically ordered, thus most likely antiferromagnetic, near room temperature.
Abstract A new experimental search for the charged-lepton-flavor-violating process of neutrinoless muon-to-electron conversion by J-PARC E21 (the COMET experiment), which aims at a factor 10 000 improvement over current limit, is described, together with physics motivation charged lepton flavor violation. The first-stage approach experiment (COMET Phase-I), has recently been taken earlier realization measurement, also mentioned.
We present the result of an indirect search for high energy neutrinos from WIMP annihilation in Sun using upward-going muon (upmu) events at Super-Kamiokande. Datasets SKI-SKIII (3109.6 days) were used analysis. looked excess neutrino signal as compared with expected atmospheric background three upmu categories: stopping, non-showering, and showering. No significant was observed. The 90% C.L. upper limits flux induced by WIMPs 100 GeV/c$^2$ 6.4$\times10^{-15}$ cm$^{-2}$ sec$^{-1}$...
We have searched for proton decay via $p \rightarrow \nu K^{+}$ using Super-Kamiokande data from April 1996 to February 2013, 260 kiloton$\cdot$year exposure in total. No evidence this mode is found. A lower limit of the lifetime set $5.9 \times 10^{33}$ years at 90% confidence level.
We report an indication that the elastic scattering rate of solar $^8$B neutrinos with electrons in Super-Kamiokande detector is larger when pass through Earth during nighttime. determine day/night asymmetry, defined as difference average day and night divided by those two rates, to be $(-3.2\pm1.1(\text{stat})\pm0.5(\text{syst}))\%$, which deviates from zero 2.7 $\sigma$. Since process mostly sensitive electron-flavored neutrinos, a non-zero asymmetry implies flavor oscillations are...
We describe the status of our effort to realize a first neutrino factory and progress made in understanding problems associated with collection cooling muons towards that end. summarize physics can be done factories as well intense cold beams muons. The potential muon colliders is reviewed, both Higgs Factories compact high energy lepton colliders. timescale research development reviewed latest designs channels including promise ring coolers achieving longitudinal transverse simultaneously....
Additional evidence for the rare kaon decay K+-->pi+nu(nu) has been found in a new data set with comparable sensitivity to previously reported result. One event was observed pion momentum region examined, 211<P<229 MeV/c, bringing total combined two. Including all taken, backgrounds were estimated contribute 0.15+/-0.05 events. The branching ratio is B(K+-->pi+nu(nu)) = 1.57(+1.75)(-0.82)x10(-10).
We have searched for proton decays via $p\ensuremath{\rightarrow}{e}^{+}{\ensuremath{\pi}}^{0}$ and $p\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\pi}}^{0}$ using data from a $91.7\text{ }\text{ }\mathrm{kt}\ifmmode\cdot\else\textperiodcentered\fi{}\mathrm{yr}$ exposure of Super-Kamiokande-I $49.2\text{ Super-Kamiokande-II. No candidate events were observed with expected backgrounds induced by atmospheric neutrinos 0.3 each decay mode. From these results, we set lower limits...
In models where the gravitino is lightest supersymmetric particle, next-to-lightest particle (NLSP) long-lived. We consider an important charged NLSP candidate, scalar tau $\stackrel{\texttildelow{}}{\ensuremath{\tau}}$. Slow NLSPs may be produced at future colliders and they stopped in a massive stopper which simultaneously serves as detector for its decay products. found number of events 1 kton to $\mathrm{O}(10) \mathrm{k}\mathrm{t}\mathrm{o}\mathrm{n}$ could significant enough study...
In this paper we study non-standard neutrino interactions as an example of physics beyond the standard model using atmospheric data collected during Super-Kamiokande I(1996-2001) and II(2003-2005) periods. We focus on flavor-changing-neutral-currents (FCNC), which allow flavor transitions via neutral current interactions, effects violate lepton non-universality (NU) give rise to different neutral-current interaction-amplitudes for flavors. obtain a limit FCNC coupling parameter,...
Super-Kamiokande atmospheric neutrino data were fit with an unbinned maximum likelihood method to search for the appearance of tau leptons resulting from interactions oscillation-generated neutrinos in detector. Relative expectation unity, normalization is found be 1.42 ± 0.35(stat)(-0.12)(+0.14)(syst) excluding no-tau-appearance hypothesis, which would zero, at 3.8σ level. We estimate that 180.1 44.3(stat)(-15.2)(+17.8) (syst) produced 22.5 kton fiducial volume detector by during 2806 day...
Searches for a nucleon decay into charged antilepton (e+ or μ+) plus light meson (π0, π−, η, ρ0, ρ−, ω) were performed using the Super-Kamiokande I and II data. Twelve modes searched for. The total exposure is 140.9 kiloton⋅years, which includes 91.7 kiloton⋅year (1489.2 live days) of Super-Kamiokande-I 49.2 (798.6 II. number candidate events in data was consistent with atmospheric neutrino background expectation. No significant evidence observed Thus, lower limits on partial lifetime at 90%...
The experimental sensitivity to μ→e conversion on nuclei is expected improve by four orders of magnitude in coming years. We consider the impact flavour-changing tensor and axial-vector four-fermion operators which couple spin nucleons. Such operators, have not previously been considered, contribute three ways: with they mediate a spin-dependent transition; all coherent (A2-enhanced) spin-independent via finite recoil effects loop mixing dipole, scalar, vector operators. estimate rate...