46 research outputs found

    Production Spectra of 3^3He(π\pi, KK) Reactions with Continuum Discretized Coupled Channels

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    We investigate theoretically Λ\Lambda production spectra of 3^3He(π\pi, KK) reactions at pπ=p_\pi= 1.05--1.20 GeV/cc in the distorted-wave impulse approximation, using the continuum-discretized coupled-channel method. The production cross section of a Λ3^3_\LambdaH(1/2+^+) ground state is also discussed.Comment: 8 pages, 4 figures; contribution to the Proceedings of the 8th International Conference on Quarks and Nuclear Physics (QNP2018), Tsukuba, November 13-17, 201

    Repulsion and absorption of the Σ\Sigma-nucleus potential for Σ\Sigma^--5^5He in the 6^6Li(π\pi^-, K+K^+) reaction

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    We study phenomenologically inclusive spectra of the 6^6Li(π\pi^-, K+K^+) reaction at 1.2 GeV/cc within a distorted-wave impulse approximation with the optimal Fermi-averaging πpK+Σ\pi^- p \to K^+ \Sigma^- tt matrix. We attempt to clarify the property of a Σ\Sigma-nucleus potential for Σ\Sigma^--5^5He by comparing the calculated spectra with the data of the J-PARC E10 experiment. The result shows that the repulsive and absorptive components of the Σ\Sigma^--5^5He potential provide the ability to explain the data of the continuum spectra in Σ\Sigma and Λ\Lambda regions; the strengths of VΣV_\Sigma \simeq +30 MeV and WΣW_\Sigma \simeq -26 MeV are favored within the Woods-Saxon potential, consistent with analyses for heavier nuclei. Effects of the size and potential range for Σ\Sigma^--5^5He in the neutron excess of (NZ)/(N+Z)=(N-Z)/(N+Z)= 0.2 are also discussed.Comment: 35 pages, 11 figure

    Discrimination of Σ\Sigma-nucleus potentials in the angular distribution of elastic scattering of Σ\Sigma^- hyperons from nuclei

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    We theoretically investigate the elastic scattering of 50-MeV Σ\Sigma^- hyperons from 28^{28}Si and 208^{208}Pb in order to clarify the radial distribution of Σ\Sigma-nucleus (optical) potentials. The angular distributions of differential cross sections are calculated using several potentials that can explain experimental data of the Σ\Sigma^- atomic X-ray and (π\pi^-, K+K^+) reaction spectra simultaneously. The magnitude and oscillation pattern of the angular distributions are understood by the use of nearside/farside decompositions of their scattering amplitudes. It is shown that the resultant angular distributions can considerably discriminate among the radial distributions of the potentials that have a repulsion inside the nuclear surface and an attraction outside the nucleus with a sizable absorption

    Medium effects on Ξ\Xi^- production in the nuclear (KK^-, K+K^+) reaction

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    We study theoretically medium effects on Ξ\Xi^- production in the (KK^-, K+K^+) reaction, using the optimal Fermi-averaging procedure which describes the Fermi motion of a nucleon on the on-energy-shell KpK+ΞK^-p\to K^+\Xi^- reaction condition in nuclei. The result shows the strong energy and angular dependence of the in-medium KpK+ΞK^-p\to K^+\Xi^- cross section,which affects significantly the shape and magnitude of the production spectrum for Ξ\Xi^- hypernuclear states in the (KK^-, K+K^+) reaction on a nuclear target.The application to the Ξ\Xi^- quasi-free production via the (KK^-, K+K^+) reaction on a 12^{12}C target is also discussed in a Fermi gas model.Comment: 18 pages, 5 figure

    Coulomb-assisted Σ\bm\Sigma^--nucleus bound states in the (KK^-, π+\pi^+) reaction

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    We study a production of Coulomb-assisted Σ\Sigma^--nucleus bound states by nuclear (KK^-, π+\pi^+) reactions within a distorted-wave impulse approximation, so as to examine several types of the Σ\Sigma-nucleus potentials that are consistent with the available Σ\Sigma^- atomic X-ray data and nuclear (π\pi^-, K+K^+) data. We theoretically demonstrate the inclusive (KK^-, π+\pi^+) spectra of the Σ\Sigma^- unstable bound states on 28^{28}Si, 58^{58}Ni, and 208^{208}Pb targets at incident KK^- lab momenta pK=400800p_{K}= 400\text{--}800 MeV/c. The results show that the near-recoilless (KK^-, π+\pi^+) reaction on the 58^{58}Ni target gives a clear candidate to confirm properties of the Σ\Sigma-nucleus potentials having a repulsion inside the nuclear surface and an attraction outside the nucleus with a sizable absorption, whereas details of the repulsion of the potential at the nuclear center cannot be determined by the inclusive spectra. This is a promising attempt to extract properties of the Σ\Sigma-nucleus potential in the nucleus at forthcoming J-PARC experiments, as a full complement to the analyses of the Σ\Sigma^- atomic and (π\pi^-, K+K^+) data

    Production of doubly strange hypernuclei via {\Xi}- doorways in the 16O(K-, K+) reaction at 1.8 GeV/c

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    We examine theoretically production of doubly strange hypernuclei, 16 {\Xi}-C and 16 {\Lambda}{\Lambda}C, in doublecharge exchange 16O(K-, K+) reactions using a distorted-wave impulse approximation. The inclusive K+ spectrum at the incident momentum pK- = 1.8 GeV/c and scattering angle {\theta}lab = 0^{\circ} is estimated in a one-step mechanism, K-p \to K+{\Xi}- via {\Xi}- doorways caused by a {\Xi}-p-{\Lambda}{\Lambda} coupling. The calculated spectrum in the {\Xi}- bound region indicates that the integrated cross sections are on the order of 7-12 nb/sr for significant 1- excited states with 14C(0+, 2+) \otimes s{\Lambda}p{\Lambda} configurations in 16 {\Lambda}{\Lambda}C via the doorway states of the spin-stretched 15N(1/2-, 3/2-) \otimes s{\Xi}- in 16 {\Xi}-C due to a high momentum transfer q{\Xi}- \approx 400 MeV/c. The {\Xi}- admixture probabilities of these states are on the order of 5-9%. However, populations of the 0+ ground state with 14C(0+) \otimes s2{\Lambda} and the 2+ excited state with 14C(2+) \otimes s2 {\Lambda} are very small. The sensitivity of the spectrum on the {\Xi}N-{\Lambda}{\Lambda} coupling strength enables us to extract the nature of {\Xi}N-{\Lambda}{\Lambda} dynamics in nuclei, and the nuclear (K-, K+) reaction can extend our knowledge of the S = -2 world.Comment: 10 pages, 3 figure

    The Japanese space gravitational wave antenna; DECIGO

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    DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. DECIGO is expected to open a new window of observation for gravitational wave astronomy especially between 0.1 Hz and 10 Hz, revealing various mysteries of the universe such as dark energy, formation mechanism of supermassive black holes, and inflation of the universe. The pre-conceptual design of DECIGO consists of three drag-free spacecraft, whose relative displacements are measured by a differential Fabry– Perot Michelson interferometer. We plan to launch two missions, DECIGO pathfinder and pre- DECIGO first and finally DECIGO in 2024

    DECIGO pathfinder

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    DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) which is a future space gravitational wave antenna. DECIGO is expected to provide us fruitful insights into the universe, in particular about dark energy, a formation mechanism of supermassive black holes, and the inflation of the universe. Since DECIGO will be an extremely large mission which will formed by three drag-free spacecraft with 1000m separation, it is significant to gain the technical feasibility of DECIGO before its planned launch in 2024. Thus, we are planning to launch two milestone missions: DPF and pre-DECIGO. The conceptual design and current status of the first milestone mission, DPF, are reviewed in this article

    The status of DECIGO

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    DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) is the planned Japanese space gravitational wave antenna, aiming to detect gravitational waves from astrophysically and cosmologically significant sources mainly between 0.1 Hz and 10 Hz and thus to open a new window for gravitational wave astronomy and for the universe. DECIGO will consists of three drag-free spacecraft arranged in an equilateral triangle with 1000 km arm lengths whose relative displacements are measured by a differential Fabry-Perot interferometer, and four units of triangular Fabry-Perot interferometers are arranged on heliocentric orbit around the sun. DECIGO is vary ambitious mission, we plan to launch DECIGO in era of 2030s after precursor satellite mission, B-DECIGO. B-DECIGO is essentially smaller version of DECIGO: B-DECIGO consists of three spacecraft arranged in an triangle with 100 km arm lengths orbiting 2000 km above the surface of the earth. It is hoped that the launch date will be late 2020s for the present

    The Japanese space gravitational wave antenna—DECIGO

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