Publications (3)0 Total impact
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Article: Search for the decay $B^0\to DK^{*0}$ followed by $D\to K^-\pi^+$
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ABSTRACT: We report a study of the decay $B^0\rightarrow D K^+\pi^-$ followed by $D\rightarrow K^-\pi^+$, where $D$ indicates $D^0$ or $\bar{D}^0$. We reconstruct the $D K^+\pi^-$ state in a phase space corresponding to $D K^{*}(892)^0$. The CP-violating angle $\phi_3$ affects its decay rate via the interference between $b\rightarrow u$ and $b\rightarrow c$ transitions. The result is obtained from a 711 ${\rm fb}^{-1}$ data sample that contains 772 $\times 10^6 B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We measure the ratio ${\cal R}_{DK^{*0}} \equiv \Gamma(B^0\rightarrow [K^-\pi^+]_DK^+\pi^-)/\Gamma(B^0\rightarrow [K^+\pi^-]_DK^+\pi^-)$ to be $(4.1 ^{+ 5.6 + 2.8}_{- 5.0 - 1.8}) \times 10^{-2}$, and set an upper limit of ${\cal R}_{DK^{*0}} < 0.16$ at the 95% confidence level.05/2012; -
Article: Precise measurement of the CP violation parameter sin2phi_1 in B0-->(c\bar c)K0 decays
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ABSTRACT: We present a precise measurement of the CP violation parameter sin2phi_1 and the direct CP violation parameter A_f using the final data sample of 772x10^6 B\bar B pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. One neutral B meson is reconstructed in a J/psi K0S, psi(2S) K0S, chi_c1 K0S or J/psi K0L CP-eigenstate and its flavor is identified from the decay products of the accompanying B meson. From the distribution of proper time intervals between the two B decays, we obtain the following CP violation parameters: sin2phi_1=0.667+-0.023(stat)+-0.012(syst) and A_f=0.006+-0.016(stat)+-0.012(syst).01/2012; -
Article: Test results of 60-kA HTS current lead for fusion application
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ABSTRACT: A 60-kA high-temperature-superconductor (HTS) current lead has been fabricated and tested aiming at the application to a fusion magnet system. The HTS current lead consists of a forced flow cooled copper part and a conduction cooled HTS part. The HTS part is composed of 288 Ag-alloy sheathed Bi-2223 tapes, which are cylindrically arrayed on a stainless steel tube. For the Ag alloy, Ag–10at.%Au is used to obtain low thermal conductivity. Operation of a 60-kA current, which is the world record, was successfully achieved at a cooling condition of 20 K, 3.2 g/s for the copper part, and a low heat leak of 4.8 W at 4.2 K was demonstrated. This result indicates that the electric power of a refrigerator to cool the current lead can be reduced by 1/3 of that in a conventional current lead. In conclusion, technology of a large HTS current lead for fusion application is established.Physica C: Superconductivity.
Institutions
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2012
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Tohoku University
- Research Center for Electron Photon Science
Sendai, Kagoshima-ken, Japan -
High Energy Accelerator Research Organization
Tsukuba, Ibaraki-ken, Japan
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