A5055794726- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- ZnO doping and properties
- Quantum and electron transport phenomena
- Semiconductor Quantum Structures and Devices
- Particle Accelerators and Free-Electron Lasers
- Superconducting Materials and Applications
- Neutrino Physics Research
- Semiconductor materials and devices
- Chalcogenide Semiconductor Thin Films
- Electronic and Structural Properties of Oxides
- Physics of Superconductivity and Magnetism
- Dark Matter and Cosmic Phenomena
- Advancements in Semiconductor Devices and Circuit Design
- Microwave Engineering and Waveguides
- Advanced Materials Characterization Techniques
- Copper-based nanomaterials and applications
- Heusler alloys: electronic and magnetic properties
- Acoustic Wave Phenomena Research
- Magnetic properties of thin films
- Black Holes and Theoretical Physics
- Magnetic and transport properties of perovskites and related materials
- Electromagnetic Compatibility and Noise Suppression
- Topological Materials and Phenomena
Osaka University
1997-2022
Nagaoka University of Technology
2016-2018
University of Fukui
2018
Nagaoka University
2016
Japan Advanced Institute of Science and Technology
2012-2014
KTH Royal Institute of Technology
2012
Kagoshima University
2005-2009
Murata (Japan)
1993-2003
High Energy Accelerator Research Organization
2003
University of Arizona
2000-2001
We have compared the decay rates of ${K}_{L}$ and ${K}_{S}$ to ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ ${\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ final states using a subset data from KTeV experiment (E832) at Fermilab. find that direct-CP-violation parameter $\mathrm{Re}({\ensuremath{\epsilon}}^{\ensuremath{'}}/\ensuremath{\epsilon})$ is equal...
We investigated the structural, magnetic, transport, and thermoelectric properties of polycrystalline delafossite oxides, $\mathrm{Cu}{\mathrm{Cr}}_{1\ensuremath{-}x}{\mathrm{Mg}}_{x}{\mathrm{O}}_{2}$ $(0\ensuremath{\leqslant}x\ensuremath{\leqslant}0.04)$. found that, with substitution ${\mathrm{Mg}}^{2+}$ ions at Cr site, resistivity Seebeck coefficient drastically decrease without a change N\'eel temperature $({T}_{N}=26\phantom{\rule{0.3em}{0ex}}\mathrm{K})$. In contrast to...
We report the first observation of a manifestly CP violating effect in K(L)-->pi(+)pi(-)e(+)e(-) decay mode. A large asymmetry was observed distribution these decays CP-odd and T-odd angle straight phi between planes e(+)e(-) pi(+)pi(-) pairs K(L) center mass system. After acceptance corrections, overall is found to be [13.6+/-2. 5(stat)+/-1.2(syst)]%. This largest CP-violating yet when integrating over entire phase space mode such an angular variable.
We present a measurement of the charge asymmetry delta(L) in mode K(L)-->pi(+/-)e(-/+)nu based on 298 x 10(6) analyzed decays. measure value = [3322+/-58(stat)+/-47(syst)]x10(-6), good agreement with previous measurements and 2.4 times more precise than current best published result. The result is used to place stringent limits CPT DeltaS DeltaQ violation neutral kaon system.
We report on a search for the decay KL→π0ν¯ν, carried out as part of E799-II, rare KL experiment at Fermilab. Within standard model, KL→π0ν¯ν is dominated by direct CP violating processes, and thus an observation implies confirmation violation. No events were observed, we set upper limit branching ratio to be <5.9×10−7 90% confidence level.Received 8 July 1999DOI:https://doi.org/10.1103/PhysRevD.61.072006©2000 American Physical Society
Narrow gap InGaAs two-dimensional electron gas (2DEG) bilayer samples are fabricated and confirmed to have good electronic qualities as well strong Rashba-type spin-orbit interactions (SOIs). The 2DEG systems realized by molecular beam epitaxy in the form of wide quantum wells (QWs) with thicknesses tQW ∼ 40–120 nm modulation doped both upper lower InAlAs barriers. From Hall measurements, overall mobility values μe ∼15 m2/V s found for total sheet density ns ∼8 × 1011/cm2, although is...
We report on a new measurement of the decay ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}\ensuremath{\gamma}$ by KTeV experiment at Fermilab. determine branching ratio to be $(1.68\ifmmode\pm\else\textpm\fi{}0.07\ifmmode\pm\else\textpm\fi{}0.08)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$. Our data show first evidence for low-mass $\ensuremath{\gamma}\ensuremath{\gamma}$ signal as predicted recent $O({p}^{6})$ chiral perturbation calculations which...
The recent discovery of a large CP violating asymmetry in KL-->pi+pi-e+e- mode has prompted us to seach for the associated KL-->pi 0 pi e+e- decay KTeV-E799 experiment at Fermilab. In 2.7 x 10(11) K(L) decays, one candidate event been observed with an expected background 0.3 event, resulting upper limit branching ratio 6.6 10(-9) 90% C.L.
Local atomic structures around Mn in $(\mathrm{Zn},\mathrm{Sn},\mathrm{Mn}){\mathrm{As}}_{2}$ thin films grown on InP (001) substrates were studied using x-ray fluorescence holography. The reconstructed three-dimensional images showed that the addition of resulted further distortions As sublattice from pure sphalerite ${\mathrm{ZnSnAs}}_{2}$. first-principles calculations distortion could be attributed to shortening Mn-As bond length induced by p-d exchange mechanism, which mediates...
We present the first measurement of form factor ratios g(1)/f(1) (direct axial vector to vector), g(2)/f(1) (second class current), and f(2)/f(1) (weak magnetism) for decay Xi(0)-->Sigma(+)e(-)nu macro(e) using KTeV (E799) beam line detector at Fermilab. From Sigma(+) polarization measured with Sigma(+)-->p pi(0) e(-)-nu; correlation, we measure be 1.32+/-(0.21)(0.17)(stat)+/-0.05(syst), assuming SU(3)(f) (flavor) values f(2)/f(1). Our results are all consistent exact symmetry.
We present results of a search for new form hadronic matter, six-quark, dibaryon state called the H0, predicted to exist in several theoretical models. Analyzing data collected by experiment E799-II at Fermilab, we searched decay H0-->Lambdappi(-) and found no candidate events. place an upper limit on [B(H0-->Lambdappi(-))dsigma(H)/dOmega]/(dsigma(Xi)/dOmega) and, context published models, exclude region lightly bound mass states just below LambdaLambda threshold, 2.194<M(H)<2.231 GeV/c(2),...
We searched for the appearance of π+π− pairs with invariant mass ≥648MeV/c2 in a neutral beam. Such an observation could signify decay long-lived light particle. find no evidence this decay. Our null result severely constrains existence R0 hadron, which is lightest bound state gluon and gluino (g˜g), thereby also gluino. Depending on photino mass, we exclude lifetime ranges 1.2–4.6GeV/c2 2×10−10–7×10−4s, respectively.Received 18 July 1997DOI:https://doi.org/10.1103/PhysRevLett.79.4083©1997...
We report on a search for the decay KL-->pi(0)e+e- carried out by KTeV/E799 experiment at Fermilab. This is expected to have significant CP violating contribution and measurement of its branching ratio could support Cabibbo-Kobayashi-Maskawa mechanism violation or point new physics. Two events were observed in 1997 data with an background 1.06+/-0.41 events, we set upper limit B(KL-->pi(0)e+e-)<5.1 x 10(-10) 90% confidence level.
We report on the analysis of rare decay K(L)-->mu(+)mu(-)gamma 1997 data from KTeV experiment at Fermilab. A total 9327 candidate events are observed with 2.4% background, representing a factor 40 increase in statistics over current world sample. find that B(K(L)-->mu(+)mu(-)gamma) = (3.62 +/- 0.04(stat) 0.08(syst)) x 10(-7). The form parameter alpha(K*) is measured to be -0.160(+0.026)(-0.028). In addition, we make first measurement alpha D'Ambrosio-Isidori-Portolés factor, finding -1.54...
We report the first branching fraction measurement of decay ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{e}^{+}{e}^{\ensuremath{-}}$. With a sample 46 candidates, and an expected background level 9.4 events, is determined to be...
Electrical spin injection experiments are performed at 1.5 K in a new hybrid structure, In0.75Ga0.25As two-dimensional electron gases with lateral Co0.8Fe0.2 electrodes. From the electrode spacing (\lesssim9 µm) dependence of spin-valve signals nonlocal regime, we obtained very promising results such as longer diffusion length Ls ∼5.1 µm and higher polarization η ∼5.7% than those former reports. They mainly attained by suppression D'yakonov–Perel' relaxation process due to tuned spin–orbit couplings.
We observe 441 K(L)-->e(+)e(-)e(+)e(-) candidate events with a background of 4.2 and measure B(K(L)-->e(+)e(-)e(+)e(-)) = [3.72+/-0.18(stat)+/-0.23(syst)]x10(-8) in the KTeV/E799II experiment at Fermilab. Using distribution angle between planes e(+)e(-) pairs, we CP parameters beta(CP) -0.23+/-0.09(stat)+/-0.02(syst) gamma(CP) -0.09+/-0.09(stat)+/-0.02(syst). also present first detailed study invariant mass spectrum this decay mode.
We have performed studies of the K(0)(L)-->pi(+)pi(-)gamma direct emission ( DE) and inner Bremsstrahlung IB) vertices, based on data collected by KTeV during 1996 Fermilab fixed target run. find a(1)/a(2) = -0.737+/-0.034 GeV2 for DE form-factor parameter in rho-propagator parametrization, report fits form factor to linear quadratic functions as well. concurrently measure gamma(K(0)(L)-->pi(+)pi(-)gamma,E(*)(gamma)>20 MeV)/gamma(K(0)(L)-->pi(+)pi(-)) (20.8+/-0.3)x10(-3), a DE/(DE+IB)...
We investigated the substitution effects of Mg2+, Ca2+, and Al3+ for Cr3+ on magnetic, transport thermal properties delafossite oxide CuCrO2, which possesses a quasi-2D Heisenberg triangular antiferromagnetic (AF) lattice. Magnetization specific heat measurements indicated that AF ordering is promoted by nonmagnetic Mg2+ (S = 3/2), despite fact spin vacancy introduced in 120° structure at Cr sites. These results suggest residual magnetic frustration partially broken fluctuations, are...
The relationship between Mn concentration and Curie temperature (TC) is studied for Mn-doped ZnSnAs2 ferromagnetic semiconductors, epitaxially grown on InP substrates by molecular beam epitaxy. In the phase, distributions in a (Zn,Mn,Sn)As2 thin film with 7.2 cation percent (cat. %) are investigated using three-dimensional atom probe tomography. results indicate an inhomogeneous distribution which spreads to relatively high of 9.0 at. % (at. %). paramagnetic it found that transition takes...
We present the first observation of Ξ0 beta decay, using KTeV beam line and detector at Fermilab. have identified 176 decay events after subtracting a 7 event background. Normalization to 41 024 simultaneously collected Ξ0→Λ0π0 decays yields branching ratio Γ(Ξ0→Σ+e−ν¯e)/Γtotal=(2.71±0.22statistical±0.31systematic)×10−4. The flavor symmetric quark model calculation agrees with this result.Received 23 December 1998DOI:https://doi.org/10.1103/PhysRevLett.82.3751©1999 American Physical Society
The magnetization of (Zn,Sn,Mn)As2 thin films epitaxially grown on InP(001) substrates exhibited an anomalous temperature dependence, increasing slightly with temperature, compared estimates based the mean-field theory (MFT). Assuming that ferromagnetic (FM) and antiferromagnetic (AF) phases coexist at low these magnetic properties can be well explained by AF-FM transition through a paramagnetic phase. Néel TN AF phase is estimated from threshold difference curve between experimental...
The branching ratio of the rare decay ${\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}$ has been measured in E799-II, a kaon experiment using KTeV detector at Fermilab. We observed 275 candidate events, with an expected background $21.4\ifmmode\pm\else\textpm\fi{}6.2$ events which includes contribution from Dalitz decays....