We report a measurement of the CP-violation parameter sin2φ1 at the Υ(5S) resonance using a new tagging method, called "B-π tagging." In Υ(5S) decays containing a neutral B meson, a charged B, and a ...charged pion, the neutral B is reconstructed in the J/ψK(S)(0) CP-eigenstate decay channel. The initial flavor of the neutral B meson at the moment of the Υ(5S) decay is opposite to that of the charged B and may thus be inferred from the charge of the pion without reconstructing the charged B. From the asymmetry between B-π(+) and B-π(-) tagged J/ψK(S)(0) yields, we determine sin2φ1=0.57±0.58(stat)±0.06(syst). The results are based on 121 fb(-1) of data recorded by the Belle detector at the KEKB e(+)e(-) collider.
We present a precise measurement of the CP violation parameter sin2φ1 and the direct CP violation parameter A(f) using the final data sample of 772×10(6) BBover ¯ pairs collected at the Υ(4S) ...resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. One neutral B meson is reconstructed in a J/ψK(S)(0), ψ(2S)K(S)(0), χ(c1)K(S)(0), or J/ψK(L)(0) 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: sin2φ1=0.667±0.023(stat)±0.012(syst) and A(f)=0.006±0.016(stat)±0.012(syst).
We report the observation of two narrow structures in the mass spectra of the π(±)Υ(nS) (n=1, 2, 3) and π(±)h(b)(mP) (m=1, 2) pairs that are produced in association with a single charged pion in ...Υ(5S) decays. The measured masses and widths of the two structures averaged over the five final states are M(1)=(10,607.2±2.0) MeV/c2, Γ(1)=(18.4±2.4) MeV, and M(2)=(10,652.2±1.5) MeV/c2, Γ(2)=(11.5±2.2) MeV. The results are obtained with a 121.4 fb(-1) data sample collected with the Belle detector in the vicinity of the Υ(5S) resonance at the KEKB asymmetric-energy e+ e- collider.
We search for CP violation in Cabibbo-suppressed charged D meson decays by measuring the difference between the CP-violating asymmetries for the Cabibbo-suppressed decays D(±)→K(+)K(-)π(±) and the ...Cabibbo-favored decays D(s)(±)→K(+)K(-)π(±) in the K(+)K(-) mass region of the ϕ resonance. Using 955 fb(-1) of data collected with the Belle detector, we obtain A(CP)(D+→ϕπ+)=(+0.51±0.28±0.05)%. The measurement improves the sensitivity of previous searches by more than a factor of 5. We find no evidence for direct CP violation.
We report the first observations of the spin-singlet bottomonium states h(b)(1P) and h(b)(2P). The states are produced in the reaction e(+)e(-)→h(b)(nP)π(+)π(-) using a 121.4 fb(-1) data sample ...collected at energies near the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We determine Mh(b)(1P)=(9898.2(-1.0-1.1)(+1.1+1.0)) MeV/c(2) and Mh(b)(2P)=(10,259.8±0.6(-1.0)(+1.4)) MeV/c(2), which correspond to P-wave hyperfine splittings ΔM(HF)=(+1.7±1.5) and (+0.5(-1.2)(+1.6)) MeV/c(2), respectively. The significances of the h(b)(1P) and h(b)(2P) are 5.5σ and 11.2σ, respectively. We find that the production of the h(b)(1P) and h(b)(2P) is not suppressed relative to the production of the Υ(1S), Υ(2S), and Υ(3S).
Early stage colorectal tumors can be removed by endoscopic mucosal resection but larger such tumors (20 mm) may require piecemeal resection. Endoscopic submucosal dissection (ESD) using newly ...developed endo-knives has enabled en-block resection of lesions regardless of size and shape. However ESD for colorectal tumor is technically difficult. Therefore, we performed EMR with small incision (EMR with SI) for more reliable EMR, ESD with snaring (simplified ESD) and ESD using the standard Flush knife and the novel ball tipped Flush knife (Flush knife BT) for easier and safer colorectal ESD.
The aims of our study were (1) to compare the treatment results of the following 3 methods (EMR with SI/si-mplified ESD/ESD) for early stage colorectal tumors, and (2) to assess the performance of Flush knife BT in colorectal ESD.
We treated 24/44/468 colorectal tumors and examined the clinicopathological features and treatment results such as tumor size, resected specimen size, procedure time, en-bloc resection rate, complication rate. We also treated 58 colorectal tumors (LST-NG:20, LST-G:36, other:2) using standard Flush knife and 80 colorectal tumors (LST-NG:32, LSTG:44, other:2) using Flush knife BT, and examined the clinicopathological features and treatment results mentioned above and also the procedure speed.
The median tumor size (mm) (EMR with SI/ simplified EMR/ESD) was 20/17/30 (EMR with SI vs. simplified ESD: p = n.s, simplified ESD vs. ESD: p < 0.0001). The median resected specimen size (mm) was 22.5/26/41 (EMR with SI vs. simplified ESD: p = 0.0018, simplified ESD vs. ESD: p < 0.0001). The procedure time (min.) was 19/27/60 (EMR with SI vs. simplified ESD: p = n.s, simplified ESD vs. ESD: p < 0.0001) The en-block resection rate (%) was 83.3/90.9 /98.9. The complication rate (post-operative bleeding rate/perforation p=n.s). In the treatment results of ESD for LSTs by knives, there was no difference between standard Flush knife and Flush knife BT for clinicopathological features and treatment results (procedure time, complication rate and en bloc R0 resection rate). However, procedure speed (cm2/min.) of LST-G was significantly faster in the Flush knife BT than in standard Flush knife. (standard Flush knife: 0.21 vs. Flush knife BT: 0.27, p = 0.034).
EMR with small incision (EMR with SI) and ESD with snaring (simplified ESD) are good option to fill the gap between EMR and ESD in the colorectum, and also considered to become the nice training for the introduction of ESD. Flush knife BT appears to improve procedure speed compared with standard Flush knife, especially for LST-G in colo-rectal ESD.
We present a new measurement of the Cabibbo-Kobayashi-Maskawa matrix element |Vcb| from B0→D*−ℓ+νℓ decays, reconstructed with the full Belle data set of 711 fb−1 integrated luminosity. Two form ...factor parametrizations, originally conceived by the Caprini-Lellouch-Neubert (CLN) and the Boyd, Grinstein and Lebed (BGL) groups, are used to extract the product F(1)ηEW|Vcb| and the decay form factors, where F(1) is the normalization factor and ηEW is a small electroweak correction. In the CLN parametrization we find F(1)ηEW|Vcb|=(35.06±0.15±0.56)×10−3, ρ2=1.106±0.031±0.007, R1(1)=1.229±0.028±0.009, R2(1)=0.852±0.021±0.006. For the BGL parametrization we obtain F(1)ηEW|Vcb|=(34.93±0.23±0.59)×10−3, which is consistent with the world average when correcting for F(1)ηEW. The branching fraction of B0→D*−ℓ+νℓ is measured to be B(B0→D*−ℓ+νℓ)=(4.90±0.02±0.16)%. We also present a new test of lepton flavor universality violation in semileptonic B decays, B(B0→D*−e+ν)B(B0→D*−μ+ν)=1.01±0.01±0.03. The errors quoted correspond to the statistical and systematic uncertainties, respectively. This is the most precise measurement of F(1)ηEW|Vcb| and form factors to date and the first experimental study of the BGL form factor parametrization in an experimental measurement.
A time projection chamber (TPC) is a strong candidate for the central tracker of the international linear collider (ILC) experiment and we have been conducting a series of cosmic ray experiments ...under a magnetic field up to 4T, using a small prototype TPC with a replaceable readout device: multi-wire proportional chamber (MWPC) or gas electron multiplier (GEM). We first confirmed that the MWPC readout could not be a fall-back option of the ILC-TPC under a strong axial magnetic field of 4T since its spatial resolution suffered severely from the so called E×B effect in the vicinity of the wire planes. The GEM readout, on the other hand, was found to be virtually free from the E×B effect and gave the resolution determined by the transverse diffusion of the drift electrons (diffusion limited). Furthermore, GEMs allow a wider choice of gas mixtures than MWPCs. Among the gases we tried so far a mixture of Ar–CF4-isobutane seems promising as the operating gas of the ILC-TPC because of its small diffusion constant especially under a strong magnetic field. We report the spatial resolution obtained with the GEM readout in this gas mixture. Also presented is the spatial resolution of a GEM-based ILC-TPC estimated from the measurement with the prototype.
We report an observation of the
$B^{\pm } \to J/\psi \eta K^{\pm }$
and
$B^0 \to J/\psi \eta K^0_S$
decays using
$772\times 10^{6}B\overline {B}$
pairs collected at the
$\Upsilon (4S)$
resonance with ...the Belle detector at the KEKB asymmetric-energy
$e^+e^-$
collider. We obtain the branching fractions
${\mathcal B}(B^{\pm }\rightarrow J/\psi \eta K^{\pm })=(1.27\pm 0.11(\hbox {stat.})\pm 0.11(\hbox {syst.}))\times 10^{-4}$
and
${\mathcal B}(B^0\to J/\psi \eta K^0_S)=(5.22 \pm 0.78 (\hbox {stat.}) \pm 0.49 (\hbox {syst.}))\times 10^{-5}$
. We search for a new narrow charmonium(-like) state
$X$
in the
$J/\psi \eta $
mass spectrum and find no significant excess. We set upper limits on the product of branching fractions,
${\mathcal B}(B^\pm \to XK^\pm){\mathcal B}(X \to J/\psi \eta)$
, at
$3872\,\hbox {MeV}\,c^{-2}$
where a
$C$
-odd partner of
$X(3872)$
may exist, at
$\psi (4040)$
and
$\psi (4160)$
assuming their known mass and width, and over a range from 3.8 to
$4.8\,\hbox {GeV}\,c^{-2}$
. The obtained upper limits at 90% confidence level for
$X^{C\hbox {-}{\rm odd}}(3872)$
,
$\psi (4040)$
, and
$\psi (4160)$
are
$3.8\times 10^{-6}$
,
$15.5\times 10^{-6}$
, and
$7.4\times 10^{-6}$
, respectively.
In this paper, we report searches for antihelium in cosmic rays using two recently flown magnetic rigidity spectrometers. BESS-TeV had extended rigidity with an MDR of 1.4
TV and had a flight ...duration of one day. BESS-Polar was optimized for collecting power. It was flown for 8.5 days and had an MDR of 240
GV. The former flight allows us to explore a previously unexplored rigidity band and the latter flight yields a factor of three improvement in the overall BESS limit. No antihelium candidate was found in the rigidity ranges of 1–500
GV, and 0.6–20
GV, among 7
×
10
4 events taken with BESS-TeV, and 8
×
10
6 events taken with BESS-Polar, respectively.
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