We report the first observation of the doubly Cabibbo-suppressed decays D(+)→K(+)η((')) using a 791 fb(-1) data sample collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) ...collider. The ratio of the branching fractions of doubly Cabibbo-suppressed relative to singly Cabibbo-suppressed D(+)→π(+)η((')) decays are B(D(+)→K(+)η)/B(D(+)→π(+)η)=(3.06±0.43±0.14)% and B(D(+)→K(+)η')/B(D(+)→π(+)η')=(3.77±0.39±0.10)%. From these, we find that the relative final-state phase difference between the tree and annihilation amplitudes in D(+) decays, δ(TA), is (72±9)° or (288±9)°. We also report the most precise measurements of CP asymmetries to date: A(CP)(D(+)→π(+)η)=(+1.74±1.13±0.19)% and A(CP)(D(+)→π(+)η')=(-0.12±1.12±0.17)%.
We measured the neutron beam polarization of the BL05/NOP (Neutron Optics and Physics) beamline at J-PARC with an accuracy of less than 10−3 using polarized 3He gas as a neutron spin analyzer. ...Precise polarimetry of the neutron beam is necessary to understand the beamline optics as well as for the asymmetry measurements of the neutron beta decay, which are planned in this beamline.
► We have measured neutron beam polarization with an accuracy of 0.03% using a 3He neutron spin filter. ► This accuracy was achieved by flipping the 3He polarization with adiabatic fast-passage (AFP) NMR. ► The 3He spin flipping canceled most of systematic uncertainties. ► Such accuracy is necessary for the precise neutron beta decay measurements planned at BL05 of the J-PARC spallation neutron source.
ATF2 is a final-focus test beam line which aims to focus the low emittance beam from the ATF damping ring to a vertical size of about 37 nm and to demonstrate nanometer level beam stability. Several ...advanced beam diagnostics and feedback tools are used. In December 2008, construction and installation were completed and beam commissioning started, supported by an international team of Asian, European, and U.S. scientists. The present status and first results are described.
The energy spectrum of cosmic-ray antiprotons (p̄'s) has been measured by BESS successively in 1993, 1995, 1997 and 1998. In total, 848 p̄'s were clearly identified in energy range 0.18–4.20 GeV. ...From these successive measurements of the p̄ spectrum at various solar activity, we discuss about the effect of the solar modulation and the origin of cosmic-ray p̄'s. The p̄/p ratios showed no distinctive year-to-year variation during the positive Sun's polarity phase.
In the colorectal tumor, the lesions suitable for the endoscopic treatment are those with no lymph node metastasis such as adenomas, intramucosal cancers, and minimally invasive submucosal cancer ...(invasion depth 1000 m, well and moderately differentiated type, no lymphovascular invasion). The new endOscopic technique, endoscopic submucosal dissection (ESD) enables en-bloc resection of the lesions regardless of their size and location. In order to perform ESD more easily, safely, and efficiently, we invented water jet short needle knives (Flush knife). Emitting a jet of water from the tip of a sheath enables submucosal local injection with a knife itself without replacement of operative instruments, which leads to efficient treatment. Especially, Flush knife is very effective for the lesions located at lower rectum and anal canal where there are many vessels. We treated a total of 361 colorectal lesions by ESD between June 2002 and July 2007, and en-block complete resection rate was 98.3 %. In 12 cases, "muscle retracting sign" was recognized. This sign is an index of the discontinuation of ESD, but it is impossible to diagnose preoperatively. The postoperative bleeding occurred in 0.8 % (3 cases: no blood transfusion is needed). The intraoperative perforation occurred in 1.9 % (6 cases: 5 cases were treated conservatively, 1 case was treated surgically) and the postoperative perforation occurred in 1 case (0.3%) treated surgically. ESD is the extremely effective treatment for the colorectal tumors and also is possible to be performed safely with the appropriate choice of the devices and strategy for dissection.
The processes γγ → ωϕ, ϕϕ, and ωω are measured using an 870 fb(-1) data sample collected with the Belle detector at the KEKB asymmetric-energy e+ e- collider. Production of vector meson pairs is ...clearly observed and their cross sections are measured for masses that range from threshold to 4.0 GeV. In addition to signals from well established spin-zero and spin-two charmonium states, there are resonant structures below charmonium threshold, which have not been previously observed. We report a spin-parity analysis for the new structures and determine the products of the η(c), χ(c0), and χ(c2) two-photon decay widths and branching fractions to ωϕ, ϕϕ, and ωω.
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