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S Okuno

Publications and source records attributed to S Okuno.

At least 19 recordsLinked to original sources
PubMed2006

Observation of B+ --> Lambda c+ Lambda c- K+ and B0 --> Lambda c+ Lambda c- K0 decays.

We report the first measurements of the doubly charmed baryonic B decays B --> Lambda c+ Lambda c- K. The B+ --> Lambda c+ Lambda c- K+ decay is observed with a branching fraction of (6.5(-0.9)(+1.0)+/-1.1+/-3.4)x10(-4) and a statistical significance of 15.4sigma. The B0 --> Lambda c+ Lambda c- K0 decay is observed with a branching fraction of (7.9(-2.3)(+2.9)+/-1.2+/-4.1)x10(-4) and a statistical significance of 6.6sigma. The branching fraction errors are statistical, systematic, and the error resulting from the uncertainty of the Lambda c+ --> pK- pi+ decay branching fraction. The analysis is based on 357 fb(-1) of data accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider.

Journal Article↗
PubMed2006

Study of J/psi-->pp[over],LambdaLambda[over] and observation of eta(c)-->LambdaLambda[over] at Belle.

We study the baryonic charmonium decays of B mesons B+-->etacK+ and B+-->J/psiK+, where the etac and J/psi subsequently decay into a pp[over] or LambdaLambda[over] pair. We measure the J/psi-->pp[over] and LambdaLambda[over] anisotropy parameters alphaB=-0.60+/-0.13+/-0.14 (pp[over]), -0.44+/-0.51+/-0.31 (LambdaLambda[over ]) and compare to results from e;{+}e;{-}-->J/psi formation experiments. We also report the first observation of etac-->LambdaLambda[over]. The measured branching fraction is B(etac-->LambdaLambda[over ])=(0.87(+0.24)/(-0.21)(stat)(+0.09/-0.14) (syst)+/-0.27(PDG))x10-3. This study is based on a 357 fb-1 data sample recorded on the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider.

Journal Article↗
PubMed2006

Observation of a near-threshold D(0)D[over](0)pi(0) enhancement in B-->D(0)D[over](0)pi(0)Kappa decay.

We report the first observation of a near-threshold enhancement in the D(0)D[over](0)pi(0) system from B-->D(0)D[over](0)pi(0)Kappa decays using a 414 fb(-1) data sample collected at the Upsilon(4S) resonance. The enhancement peaks at a mass M=3875.2+/-0.7(+0.3)/(-1.6) +/-0.8 MeV/c2 and the branching fraction for events in the peak is B(B-->D(0)D[over](0)pi(0)Kappa)=(1.22+/-0.31(+0.23)/(-0.30))x10(-4). The data were collected with the Belle detector at the KEKB energy-asymmetric e+ e- collider.

Journal Article↗
PubMed2006

Measurement of the quark mixing parameter cos2phi1 using time-dependent Dalitz analysis of B0 -->D[KS(0)pi + pi-]h0.

We present a measurement of the angle phi1 of the Cabibbo-Kobayashi-Maskawa unitarity triangle using a time-dependent Dalitz analysis of D-->KS(0)pi + pi- decays produced in neutral B meson decay to a neutral D meson and a light meson (B0-->D*h0). The method allows a direct extraction of 2phi1 and, therefore, helps to resolve the ambiguity between 2phi1 and pi-2phi1 in the measurement of sin2phi1. We obtain sin2phi1= 0.78 +/- 0.44 +/- 0.22 and cos2varphi1 = 1.87(-0.53-0.32)(+0.40 + 0.22). The sign of cos2phi1 is determined to be positive at 98.3% C.L.

Journal Article↗
PubMed2006

Measurement of D0-->pilnu(Klnu) form factors and absolute branching fractions.

Using a 282 fb-1 data sample collected by the Belle experiment at the KEKB e+e- collider, we study D0 decays to K-l+nu and pi-l+nu final states. The D0 flavor and momentum are tagged through a full reconstruction of the recoiling charm meson and additional mesons from fragmentation. The reconstruction method provides very good resolution in neutrino momentum and in q2=(pl+pnu)2. Normalizing to the total number of D0 tags, we measure the absolute branching fractions to be B(D0-->Klnu)=(3.45+/-0.07stat+/-0.20syst)% and B(D0-->pilnu)=(0.255+/-0.019stat+/-0.016syst)% and the semileptonic form factors (within the modified pole model) f+K(0)=0.695+/-0.007stat+/-0.022syst and f+pi(0)=0.624+/-0.020stat+/-0.030syst.

Journal Article↗
PubMed2006

Role of fibroblast growth factor-23 in peripheral vascular calcification in non-diabetic and diabetic hemodialysis patients.

INTRODUCTION: Fibroblast growth factor (FGF) 23 is a recently identified circulating factor that regulates phosphate (Pi) metabolism. Since the derangement of Pi control is an important risk factor for vascular calcification, we investigated the importance of plasma FGF-23 in the development of vascular calcification in the aorta and peripheral artery in hemodialysis patients with and without diabetes mellitus (DM). METHODS: Male hemodialysis patients with DM (n=32) and without DM (n=56) were examined. Plasma samples were obtained before the start of dialysis sessions, and the FGF-23 levels were determined by enzyme-linked immunosorbent assay. Roentgenography of the aorta and hand artery was performed, and visible vascular calcification was evaluated by one examiner, who was blinded to the patient characteristics. RESULTS: In the 56 non-DM hemodialysis patients, vascular calcification was found in the hand artery in 5 patients (8.9%) and in the aorta in 23 patients (41.1%). These levels were significantly lower (p<0.05) than in the 32 DM patients, of whom, 19 (59.4%) and 21 (65.6%) had vascular calcification of the hand artery and aorta, respectively. Multiple regression analyses performed separately in the non-DM and DM patients showed that the plasma FGF-23 level, CaxPi product, and body weight are independent factors significantly associated with hand-artery calcification and that diastolic blood pressure is associated with aorta calcification in non-DM patients. In DM patients, the plasma FGF-23 level and hemodialysis duration emerged as independent factors associated with hand-artery calcification and diastolic blood pressure was associated with aorta calcification. The independent association of the plasma FGF-23 level with hand-artery calcification was retained in both non-DM and DM patients when adjusted for the CaxPi product. CONCLUSION: Our findings show that the plasma FGF-23 level is an independent factor negatively associated with peripheral vascular calcification in the hand artery, but not in the aorta, in both male non-DM and DM hemodialysis patients, even when adjusted for the CaxPi product. This study raises the possibility that the plasma FGF-23 level may provide a reliable marker for Moenckeberg's medial calcification in male hemodialysis patients, independent of its regulatory effect on Pi metabolism.

Adult↗
PubMed2006

Measurement of forward-backward asymmetry and Wilson coefficients in B --> K*l+l-.

We report the first measurement of the forward-backward asymmetry and the ratios of Wilson coefficients and in A9/A7 and A10/A7 in B --> K*l+l-, where l represents an electron or a muon. We find evidence for the forward-backward asymmetry with a significance of 3.4sigma. The results are obtained from a data sample containing 386 x 10(6) BB pairs that were collected on the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.

Journal Article↗
PubMed2006

Measurement of azimuthal asymmetries in inclusive production of hadron pairs in e(+)e(-) annihilation at Belle.

The Collins effect connects transverse quark spin with a measurable azimuthal dependence in the yield of hadronic fragments around the quark's momentum vector. Using two different reconstruction methods, we find evidence of statistically significant azimuthal asymmetries for charged pion pairs in e(+)e(-) annihilation at a center-of-mass energy of 10.52 GeV, which can be attributed to a transverse polarization of the primordial quarks. The measurement was performed using a sample of 79 x 10(6) hadronic events collected with the Belle detector.

Journal Article↗
PubMed2006

Observation of a chi(c2)' candidate in gamma gamma --> DD production at belle.

We report on a search for new resonant states in the process gamma gamma --> DD. A candidate C-even charmonium state is observed in the vicinity of 3.93 GeV/c2. The production rate and the angular distribution in the gamma gamma center-of-mass frame suggest that this state is the previously unobserved chi(c2)', the 2(3)P2 charmonium state.

Journal Article↗
PubMed2005

Measurements of the branching fraction and polarization in B+ --> rho+ K*0 decays.

We present the results of a study of the charmless vector-vector decay B+ --> rho+ K*0, based on 253 fb(-1) of data collected with the Belle detector at the KEKB asymmetric-energy e+ e- collider. We obtain the branching fraction B(B+ --> rho+ K*0) = [8.9 +/- 1.7(stat) +/- 1.2(syst)] x 10(-6). We also perform a helicity analysis of the rho and K* vector mesons, and obtain the longitudinal polarization fraction f(L)(B+ --> rho+ K*0) = 0.43 +/- 0.11(stat)(-0.02)(+0.05) (syst).

Journal Article↗
PubMed2005

Observation of a near-threshold omegaJ/psi mass enhancement in exclusive B-->KomegaJ/psi decays.

We report the observation of a near-threshold enhancement in the omegaJ/psi invariant mass distribution for exclusive B-->KomegaJ/psi decays. The results are obtained from a 253 fb(-1) data sample that contains 275 x 10(6) BB pairs that were collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e(+)e(-) collider. The statistical significance of the omegaJ/psi mass enhancement is estimated to be greater than 8sigma.

Journal Article↗
PubMed2005

Study of B0-->rho+/- pi-/+ time-dependent CP violation at Belle.

We present a time-dependent analysis of CP violation in B0-->rho(+/-)pi(-/+) decays based on a 140 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at KEKB. We obtain the charge asymmetry A(rhopi)(CP)=-0.16+/-0.10(stat)+/-0.02(syst). An unbinned maximum-likelihood fit to the Deltat distributions yields C(rhopi)=0.25+/-0.17(stat)+0.02-0.06(syst), DeltaC(rhopi)=0.38+/-0.18(stat)+0.02-0.04(syst), S(rhopi)=-0.28+/-0.23(stat)+0.10-0.08(syst), and DeltaS(rhopi)=-0.30+/-0.24(stat)+/-0.09(syst). The direct CP violation parameters for B-->rho(+)pi(-) and B-->rho(-)pi(+) decays are A(+-)(rhopi)=-0.02+/-0.16(stat)+0.05-0.02(syst) and A(-+)(rhopi)=-0.53+/-0.29(stat)+0.09-0.04(syst).

Journal Article↗
PubMed2005

Observation of an isotriplet of excited charmed baryons decaying to lambda+c pi.

We report the observation of an isotriplet of excited charmed baryons, decaying into Lambda(+)(c)pi(-), Lambda(+)(c)pi(0), and Lambda(+)(c)pi(+). We measure the mass differences M(Lambda(+)(c)pi)-M(Lambda(+)(c)) and widths to be 515.4(+3.2+2.1)(-3.1-6.0) MeV/c(2), 61(+18+22)(-13-13) MeV for the neutral state; 505.4(+5.8+12.4)(-4.6-2.0) MeV/c(2), 62(+37+52)(-23-38) MeV for the charged state; and 514.5(+3.4+2.8)(-3.1-4.9) MeV/c(2), 75(+18+12)(-13-11) MeV for the doubly charged state, where the uncertainties are statistical and systematic, respectively. These results are obtained from a 281 fb(-1) data sample collected with the Belle detector near the Upsilon(4S) resonance, at the KEKB asymmetric energy e(+)e(-) collider.

Journal Article↗
PubMed2005

Observation of B+-->K1(1270)+gamma.

We report the observation of the radiative decay B+-->K1(1270)(+) gamma using a data sample of 140 fb(-1) taken at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- collider. We find the branching fraction to be B(B+-->K1(1270)(+)gamma)=(4.3+/-0.9(stat.)+/-0.9(syst.))x10(-5) with a significance of 7.3sigma. We find no significant signal for B+-->K1(1400)(+)gamma and set an upper limit B(B+-->K1(1400)(+)gamma)<1.5 x 10(-5) at the 90% confidence level. We also measure inclusive branching fractions for B+-->K+pi+pi-gamma and B0-->K0pi+pi-gamma in the mass range 1 GeV/c(2)<M(K+(0)pi+pi-)<2 GeV/c(2).

Journal Article↗
PubMed2005

Increased incidence of vertebral fracture in older female hemodialyzed patients with type 2 diabetes mellitus.

Bone disease in hemodialysis (HD) patients with type 2 diabetes mellitus (DM) is characterized by low bone turnover (Inaba M, et al. Am J Kidney Dis 2002; 39:1261-1269), although their bone quality is yet to be determined. The present study was designed to examine whether the prevalence of vertebral fracture in female HD patients with type 2 DM, age 65 years and older, might be increased, and the relation of this fracture to bone mineral density (BMD) determined by dual X-ray absorptiometry (DXA), since few data are available on the effect of DM on bone strength at lumbar spine. The prevalence of vertebral fracture in type 2 DM HD patients was 32.3%, which was greater than that of non-DM HD patients (13.3%) when adjusted for age and HD duration. Logistic regression analysis elucidated the presence of DM and age as independent risk factors for an increased prevalence of vertebral fracture in HD patients. In non-DM HD patients, those with vertebral fracture showed age significantly higher and BMD in either lumbar spine or distal one third of radius significantly lower than the respective value in those without fracture. However, in DM HD patients, neither BMD in lumbar spine nor distal one third of radius was significantly lower in those with vertebral fracture than in those without. Furthermore, age did not differ significantly between DM HD patients with and without fracture. In conclusion, female type 2 DM HD patients, age 65 years and older, showed significantly higher incidence of vertebral fracture than non-DM HD patients. Although age and low BMD emerged as independent risk factors for vertebral fracture in non-DM HD patients, those factors failed to be a risk factor in DM HD patients, suggesting that BMD determined by DXA might not be reliable in assessing bone strength in DM HD patients.

Absorptiometry, Photon↗
PubMed2004

Observation of B+-->LambdaLambdaK+.

We report the first observation of the charmless hyperonic B decay, B+-->LambdaLambdaK+, using a 140 fb(-1) data sample recorded at the Upsilon(4S) resonance with the Belle detector at the KEKB (e+)(e-) collider. The measured branching fraction is B(B+-->LambdaLambdaK+) = (2.91(+0.90)(-0.70) +/- 0.38) x 10(-6). We also perform a search for the related decay mode B+-->LambdaLambdapi+, but do not find a significant signal. We set a 90% confidence-level upper limit of B(B+-->LambdaLambdapi+) < 2.8 x 10(-6).

Journal Article↗
PubMed2004

Evidence for B+-->omegal+nu.

We have searched for the decay B+-->omegal(+)nu (l=e or mu) in 78 fb(-1) of Upsilon(4S) data (85x10(6)BB events) accumulated with the Belle detector. The final state is fully reconstructed using the omega decay into pi(+)pi(-)pi(0), combined with detector hermeticity to estimate the neutrino momentum. A signal of 414+/-125 events is found in the data, corresponding to a branching fraction of (1.3+/-0.4+/-0.2+/-0.3)x10(-4), where the first two errors are statistical and systematic, respectively. The third error reflects the estimated form-factor uncertainty.

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