M. Sumihama
A5072186689- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Neutrino Physics Research
- Nuclear physics research studies
- Computational Physics and Python Applications
- Particle Detector Development and Performance
- Particle Accelerators and Free-Electron Lasers
- Dark Matter and Cosmic Phenomena
- Black Holes and Theoretical Physics
- Medical Imaging Techniques and Applications
- Superconducting Materials and Applications
- Atomic and Subatomic Physics Research
- Advanced NMR Techniques and Applications
- Advanced X-ray Imaging Techniques
- Astrophysics and Cosmic Phenomena
- Radiopharmaceutical Chemistry and Applications
- Nuclear Physics and Applications
- Advanced Data Storage Technologies
- Atomic and Molecular Physics
- Advanced MRI Techniques and Applications
- Muon and positron interactions and applications
- Chemical Reactions and Isotopes
- Physics of Superconductivity and Magnetism
- Cosmology and Gravitation Theories
Gifu University
2014-2023
University of Cincinnati
2013-2023
Osaka University
2003-2022
Jožef Stefan Institute
2015
University of Maribor
2015
Tohoku University
2008-2014
University of Bonn
2013
University of Giessen
2013
University of the Basque Country
2013
Campbell Collaboration
2012
The gamman-->K(+)K(-)n reaction on 12C has been studied by measuring both K+ and K- at forward angles. A sharp baryon resonance peak was observed 1.54+/-0.01 GeV/c(2) with a width smaller than 25 MeV/c(2) Gaussian significance of 4.6sigma. strangeness quantum number (S) the is +1. It can be interpreted as molecular meson-baryon or alternatively an exotic five-quark state (uuddsmacr;) that decays into neutron. consistent lowest member antidecuplet baryons predicted chiral soliton model.
Differential cross sections and photon beam asymmetries for the gamma p rightarrow K+ Lambda Sigma0 reactions have been measured in energy range from 1.5 GeV to 2.4 angular Theta_{cm} = 0 60 of scattering angle center mass system at SPring-8/LEPS facility. The both found be positive increase with energy. differential agree data by CLAS collaboration cosTheta_{cm}<0.9 within experimental uncertainties, but discrepancy SAPHIR K+Lambda reaction is large cosTheta_{cm}>0.9. In reaction,...
Excitation energy spectra of 89ΛY, 51ΛV, and 12ΛC have been measured via the (π+,K+) reaction by using SKS spectrometer at K6 beam line in KEK 12-GeV Proton Synchrotron. In 89ΛY spectrum, obtained with an resolution 1.65 MeV (FWHM) highest statistics so far, we succeeded clearly observing a characteristic fine structure heavy Λ hypernuclear systems precisely obtaining series single-particle energies very wide excitation range more than 20 MeV, for first time. Also 51ΛV similar to that was...
The photo-production of ϕ mesons from Li, C, Al, and Cu at forward angles has been measured Eγ=1.5–2.4GeV. number events for incoherent is found to have a target mass dependence A0.72±0.07 in the kinematical region |t|⩽0.6GeV2/c2. total cross section ϕ–nucleon interaction, σϕN, estimated as 35−11+17mb using A-dependence yield Glauber-type multiple scattering theory. This value much larger than σϕN free space, suggesting that properties might change nuclear medium.
The γd→K+K−pn reaction has been studied to search for the evidence of Θ+ by detecting K+K− pairs at forward angles. Fermi-motion-corrected nK+ invariant mass distribution shows a narrow peak 1.524±0.002+0.003 GeV/c2. statistical significance calculated from shape analysis is 5.1 σ, and differential cross section γn→K−Θ+ estimated be 12±2 nb/sr in photon energy range 2.0 2.4 GeV LEPS angular assuming isotropic production γn center-of-mass system. obtained results support existence Θ+.9...
Differential cross sections for γp→K+Λ(1405) and γp→K+Σ0(1385) reactions have been measured in the photon energy range from 1.5 to 2.4 GeV angular of 0.8<cos(Θ)<1.0 K+ scattering angle center-of-mass system. This data is first measurement Λ(1405) photoproduction section. The line shapes Σ+π− Σ−π+ decay modes were different with each other, indicating a strong interference isospin 0 1 terms Σπ amplitudes. ratios production Σ0(1385) two ranges: near threshold (1.5<Eγ<2.0 GeV) far it...
The interference fragmentation function translates the of a quark with transverse projection spin into an azimuthal asymmetry two final-state hadrons. In e+e- annihilation product functions is measured. We report nonzero asymmetries for pairs charge-ordered pi+pi- pairs, which indicate significant in this channel. results are obtained from 672 fb-1 data sample that contains 711 \times 106 and was collected at near ?(4S) resonance, Belle detector KEKB asymmetric-energy collider.
An experiment with a newly developed high-resolution kaon spectrometer (HKS) and scattered electron novel configuration was performed in Hall C at Jefferson Lab (JLab). The ground state of neutron-rich hypernucleus, He 7 Lambda, observed for the first time (e,e'K+) reaction an energy resolution ~0.6 MeV. This is best reported to date hypernuclear spectroscopy. he Lambda binding supplies last missing information A=7, T=1 iso-triplet, providing new input charge symmetry breaking (CSB) effect...
The spin-orbit splitting of Lambda single-particle states in (13)(Lambda)C was measured. 13C(K-,pi(-))(13)(Lambda)C reaction used to excite both the 1/2(-) and 3/2(-) simultaneously, which have predominantly 12C(0(+)) x p(Lambda) configuration. gamma rays from ground state were measured coincidence with pi(-)'s, by ls found be 152+/-54(stat)+/-36(syst) keV. value is 20-30 times smaller than exhibited nuclear shell model. This gives us new insight into YN interaction.
Beam polarization asymmetries for the p(gamma-->,K+)Lambda and p(gamma-->,K+)Sigma(0) reactions are measured first time E(gamma)=1.5-2.4 GeV 0.6<cos((theta(c.m.)(K+))<1.0 by using linearly polarized photons at Laser-Electron-Photon facility SPring-8 (LEPS). The observed positive gradually increase with rising photon energy. data not consistent theoretical predictions based on tree-level effective-Lagrangian approaches. Including new results in development of models is, therefore, crucial...
Photoproduction of a phi meson on protons was studied by means linearly polarized photons at forward angles in the low-energy region from threshold to Egamma = 2.37 GeV. The differential cross sections t -|t|min do not increase smoothly as increases but show local maximum around 2.0 angular distributions demonstrate that mesons are photoproduced predominantly helicity-conserving processes, and is likely due unnatural-parity processes.
The 1H(e,e′π+)n cross section was measured for arange of four-momentum transfer up to Q2=3.91GeV2 at values the invariant mass W above resonance region. Q2 dependence longitudinal component found be consistent with Q2-scaling prediction hard exclusive processes. This suggests that QCD factorization theorem is applicable rather low Q2. transverse term falls off slower than naive Q−8 expectation and remains appreciable even Q2=3.91GeV2.Received 12 July...
We have measured the nuclear transparency of A(e,e′π+) process in H2, C12, Al27, Cu63, and Au197 targets. These measurements were performed at Jefferson Laboratory over a four momentum transfer squared range Q2=1.1 to 4.7 (GeV/c)2. The was extracted as super-ratio (σA/σH) from data model pion-electroproduction nuclei without π−N final-state interactions. Q2 atomic number dependence both show deviations traditional physics expectations are consistent with calculations that include quantum...
Differential cross sections and photon-beam asymmetries for the gamma p -> K+ Lambda(1520) reaction have been measured with linearly polarized photon beams at energies from threshold to 2.4 GeV 0.6<cos(theta)<1. A new bump structure was found W=2.11 in sections. The is not well reproduced by theoretical calculations introducing a nucleon resonance J<=3/2. This result suggests that might be produced possibly J>=5/2 or process, example an interference effect phi photoproduction having similar
We measure the inclusive production cross sections of hyperons and charmed baryons from ${e}^{+}{e}^{\ensuremath{-}}$ annihilation using a $800\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ data sample taken near $\mathrm{\ensuremath{\Upsilon}}(4S)$ resonance with Belle detector at KEKB asymmetric-energy collider. The feed-down contributions heavy particles are subtracted our data, direct presented for first time. divided by number spin states $S=\ensuremath{-}1$ follow an exponential...
The ${}_{\ensuremath{\Lambda}}^{13}\mathrm{C}$ hypernucleus was studied by measuring $\ensuremath{\gamma}$ rays in coincidence with the ${}^{13}\mathrm{C}{(K}^{\ensuremath{-}},{\ensuremath{\pi}}^{\ensuremath{-}})$ reaction. from ${1/2}^{\ensuremath{-}}$ and ${3/2}^{\ensuremath{-}}$ states, which are partners of spin-orbit doublet states a predominant configuration ${[}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.}{(0}^{+})\ensuremath{\bigotimes}{p}_{\ensuremath{\Lambda}}],$ to ground state were...
Photoproduction of Lambda(1520) with liquid hydrogen and deuterium targets was examined at photon energies below 2.4 GeV in the SPring-8 LEPS experiment. For first time, differential cross sections were measured low a target. A large asymmetry production from protons neutrons observed backward K+/0 angles. This suggests importance contact term, which coexists t-channel K exchange under gauge invariance. interpretation compatible sections, decay asymmetry, beam forward K+
We report preliminary results on the analysis of three-body Y(10860)=> B barB pi, Y(10860) => (B barB* + c.c.) pi and B* decays including an observation Zb(10610)+- pi-+ [B barB*+c.c]+- Zb(10650)+- [B* barB*]+- as intermediate channels. measure branching fractions to be Br(Y(10860)=> barB*+c.c.]+- pi-+)=(28.3+-2.9+-4.6)x10^{-3} pi-+)=(14.1+-1.9+-2.4)x10^{-3} set 90% C.L. upper limit barB]+- pi-+)<4.0x10^{-3}. also amplitude Y(10860)=>Y(nS)pi+pi-, n=1,2,3 internal structure...
Differential cross sections and decay asymmetries for coherent $ϕ$-meson photoproduction from deuterons were measured the first time at forward angles using linearly polarized photons $E_γ$= 1.5-2.4 GeV. This reaction offers a unique way to directly access natural-parity Pomeron dynamics gluon exchange low energies. The zero degrees increase with increasing photon energy. demonstrate complete dominance of processes, showing that isovector unnatural-parity $π$-meson is small. Nevertheless...
The Σ(1385) resonance, or Σ*, is well known as part of the standard baryon decuplet with spin J=32. Measurements reaction γp→K+Σ*0 are difficult to extract due overlap nearby Λ(1405) resonance. However, γn→K+Σ*− has no its charge. Here we report first measurement cross sections and beam asymmetries for photoproduction Σ*− from a deuteron target. at forward angles range 0.4 1.2 μb, broad maximum near Eγ≃1.8 GeV. negative, in contrast positive values γn→K+Σ− reaction.Received 19 September...
Cross sections for the $^{1}\mathrm{H}$($e,{e}^{\ensuremath{'}}{\ensuremath{\pi}}^{+})n$ process on $^{1}\mathrm{H}$, $^{2}\mathrm{H}$, $^{12}\mathrm{C}$, $^{27}\mathrm{Al}$, $^{63}\mathrm{Cu}$, and $^{197}\mathrm{Au}$ targets were measured at Thomas Jefferson National Accelerator Facility (Jefferson Lab) to extract nuclear transparencies. Data taken from ${Q}^{2}=1.1$--4.7 GeV${}^{2}$ a fixed center-of-mass energy of $W=2.14$ GeV. The ratio ${\ensuremath{\sigma}}_{L}$...
The LEPS/SPring-8 experiment made a comprehensive measurement of the spin-density matrix elements for γp→ϕp, γd→ϕpn, and γd→ϕd at forward production angles. A linearly polarized photon beam Eγ=1.6–2.4 GeV was used ϕ mesons. natural-parity Pomeron exchange processes remain dominant near threshold. unnatural-parity pseudoscalar is visible in from nucleons but greatly reduced coherent deuterons. There no strong Eγ dependence, there some dependence on momentum transfer. small finite value...
The $\phi$-$\Lambda(1520)$ interference effect in the $\gamma p\to K^+K^-p$ reaction has been measured for first time energy range from 1.673 to 2.173 GeV. relative phases between $\phi$ and $\Lambda(1520)$ production amplitudes were obtained kinematic region where two resonances overlap. measurement results support strong constructive when $K^+K^-$ pairs are observed at forward angles, but destructive proton emission angles. Furthermore, does not account $\sqrt{s}=2.1$ GeV bump structure...
We have measured the neutron spectra emitted in weak decay of $_{\ensuremath{\Lambda}}^{12}\mathrm{C}$ and $_{\ensuremath{\Lambda}}^{89}\mathrm{Y}$ over energy region above $10\phantom{\rule{0.3em}{0ex}}\text{MeV}$ $({\ensuremath{\pi}}^{+},{K}^{+})$ reaction with better statistics an improved signal-to-background ratio. The yields nonmesonic decays were obtained from spectra. By using proton yield $_{\ensuremath{\Lambda}}^{12}\mathrm{C}$, ${\ensuremath{\Gamma}}_{n}∕{\ensuremath{\Gamma}}_{p}$...