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An absolute measurement of the Λ_{c}^{+} lifetime is reported using Λ_{c}^{+}âpK^{-}π^{+} decays in events reconstructed from data collected by the Belle II experiment at the SuperKEKB asymmetric-energy electron-positron collider. The total integrated luminosity of the data sample, which was collected at center-of-mass energies at or near the Ï(4S) resonance, is 207.2 fb^{-1}. The result, τ(Λ_{c}^{+})=203.20±0.89±0.77 fs, where the first uncertainty is statistical and the second systematic, is the most precise measurement to date and is consistent with previous determinations.
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Using the data sample of 980 fb^{-1} collected with the Belle detector operating at the KEKB asymmetric-energy e^{+}e^{-} collider, we present the results of an investigation of the Λπ^{+} and Λπ^{-} invariant mass distributions looking for substructure in the decay Λ_{c}^{+}âΛπ^{+}π^{+}π^{-}. We find a significant signal in each mass distribution. When interpreted as resonances, we find for the Λπ^{+} (Λπ^{-}) combination a mass of 1434.3±0.6(stat)±0.9(syst) MeV/c^{2} [1438.5±0.9(stat)±2.5(syst) MeV/c^{2}], an intrinsic width of 11.5±2.8(stat)±5.3(syst) MeV/c^{2} [33.0±7.5(stat)±23.6(syst) MeV/c^{2}] with a significance of 7.5σ (6.2σ). As these two signals are very close to the K[over ¯]N threshold, we also investigate the possibility of a K[over ¯]N cusp, and find that we cannot discriminate between these two interpretations due to the limited size of the data sample.
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We present the first search for the pair production of dark particles X via K_{L}^{0}âXX with X decaying into two photons using the data collected by the KOTO experiment. No signal was observed in the mass range of 40-110 MeV/c^{2} and 210-240 MeV/c^{2}. This sets upper limits on the branching fractions as B(K_{L}^{0}âXX)<(1-4)×10^{-7} and B(K_{L}^{0}âXX)<(1-2)×10^{-6} at the 90% confidence level for the two mass regions, respectively.
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The differential cross sections of the Σ^{-}pâΛn reaction were measured accurately for the Σ^{-} momentum (p_{Σ}) ranging from 470 to 650 MeV/c at the J-PARC Hadron Experimental Facility. Precise angular information about the Σ^{-}pâΛn reaction was obtained for the first time by detecting approximately 100 reaction events at each angular step of Δcosθ=0.1. The obtained differential cross sections show a slightly forward-peaking structure in the measured momentum regions. The cross sections integrated for -0.7≤cosθ≤1.0 were obtained as 22.5±0.68 [statistical error(stat.)] ±0.65 [systematic error(syst.)] mb and 15.8±0.83(stat)±0.52(syst) mb for 470
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The rare decay K_{L}âπ^{0}νν[over ¯] was studied with the dataset taken at the J-PARC KOTO experiment in 2016, 2017, and 2018. With a single event sensitivity of (7.20±0.05_{stat}±0.66_{syst})×10^{-10}, three candidate events were observed in the signal region. After unveiling them, contaminations from K^{±} and scattered K_{L} decays were studied, and the total number of background events was estimated to be 1.22±0.26. We conclude that the number of observed events is statistically consistent with the background expectation. For this dataset, we set an upper limit of 4.9×10^{-9} on the branching fraction of K_{L}âπ^{0}νν[over ¯] at the 90% confidence level.
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In an emulsion-counter hybrid experiment performed at J-PARC, a Ξ^{-} absorption event was observed which decayed into twin single-Λ hypernuclei. Kinematic calculations enabled a unique identification of the reaction process as Ξ^{-}+^{14}Nâ_{Λ}^{10}Be+_{Λ}^{5}He. For the binding energy of the Ξ^{-} hyperon in the Ξ^{-}-^{14}N system a value of 1.27±0.21 MeV was deduced. The energy level of Ξ^{-} is likely a nuclear 1p state which indicates a weak ΞN-ΛΛ coupling.
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We measured missing mass spectrum of the ^{12}C(γ,p) reaction for the first time in coincidence with potential decay products from η^{'} bound nuclei. We tagged an (η+p) pair associated with the η^{'}NâηN process in a nucleus. After applying kinematical selections to reduce backgrounds, no signal events were observed in the bound-state region. An upper limit of the signal cross section in the opening angle cosθ_{lab}^{ηp}<-0.9 was obtained to be 2.2 nb/sr at the 90% confidence level. It is compared with theoretical cross sections, whose normalization ambiguity is suppressed by measuring a quasifree η^{'} production rate. Our results indicate a small branching fraction of the η^{'}NâηN process and/or a shallow η^{'}-nucleus potential.
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We report the first observation of the double strange baryon Ξ(1620)^{0} in its decay to Ξ^{-}π^{+} via Ξ_{c}^{+}âΞ^{-}π^{+}π^{+} decays based on a 980 fb^{-1} data sample collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. The mass and width are measured to be 1610.4±6.0(stat)_{-4.2}^{+6.1} (syst) MeV/c^{2} and 59.9±4.8(stat)_{-7.1}^{+2.8}(syst) MeV, respectively. We obtain 4.0σ evidence of the Ξ(1690)^{0} with the same data sample. These results shed light on the structure of hyperon resonances with strangeness S=-2.
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We report the first observation of the spontaneous polarization of Λ and Λ[over ¯] hyperons transverse to the production plane in e^{+}e^{-} annihilation, which is attributed to the effect arising from a polarizing fragmentation function. For inclusive Λ/Λ[over ¯] production, we also report results with subtracted feed-down contributions from Σ^{0} and charm. This measurement uses a dataset of 800.4 fb^{-1} collected by the Belle experiment at or near a center-of-mass energy of 10.58 GeV. We observe a significant polarization that rises with the fractional energy carried by the Λ/Λ[over ¯] hyperon.
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A search for the rare decay K_{L}âπ^{0}νν[over ¯] was performed. With the data collected in 2015, corresponding to 2.2×10^{19} protons on target, a single event sensitivity of (1.30±0.01_{stat}±0.14_{syst})×10^{-9} was achieved and no candidate events were observed. We set an upper limit of 3.0×10^{-9} for the branching fraction of K_{L}âπ^{0}νν[over ¯] at the 90% confidence level (C.L.), which improved the previous limit by almost an order of magnitude. An upper limit for K_{L}âπ^{0}X^{0} was also set as 2.4×10^{-9} at the 90% C.L., where X^{0} is an invisible boson with a mass of 135 MeV/c^{2}.
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We present first evidence that the cosine of the CP-violating weak phase 2ß is positive, and hence exclude trigonometric multifold solutions of the Cabibbo-Kobayashi-Maskawa (CKM) Unitarity Triangle using a time-dependent Dalitz plot analysis of B^{0}âD^{(*)}h^{0} with DâK_{S}^{0}π^{+}π^{-} decays, where h^{0}∈{π^{0},η,ω} denotes a light unflavored and neutral hadron. The measurement is performed combining the final data sets of the BABAR and Belle experiments collected at the Ï(4S) resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain (471±3)×10^{6}BB[over ¯] pairs recorded by the BABAR detector and (772±11)×10^{6}BB[over ¯] pairs recorded by the Belle detector. The results of the measurement are sin2ß=0.80±0.14(stat)±0.06(syst)±0.03(model) and cos2ß=0.91±0.22(stat)±0.09(syst)±0.07(model). The result for the direct measurement of the angle ß of the CKM Unitarity Triangle is ß=[22.5±4.4(stat)±1.2(syst)±0.6(model)]°. The measurement assumes no direct CP violation in B^{0}âD^{(*)}h^{0} decays. The quoted model uncertainties are due to the composition of the D^{0}âK_{S}^{0}π^{+}π^{-} decay amplitude model, which is newly established by performing a Dalitz plot amplitude analysis using a high-statistics e^{+}e^{-}âcc[over ¯] data sample. CP violation is observed in B^{0}âD^{(*)}h^{0} decays at the level of 5.1 standard deviations. The significance for cos2ß>0 is 3.7 standard deviations. The trigonometric multifold solution π/2-ß=(68.1±0.7)° is excluded at the level of 7.3 standard deviations. The measurement resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle.
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We report on the first observation of γ rays emitted from an sd-shell hypernucleus, _{Λ}^{19}F. The energy spacing between the ground state doublet, 1/2^{+} and 3/2^{+} states, of _{Λ}^{19}F is determined to be 315.5±0.4(stat)_{-0.5}^{+0.6}(syst) keV by measuring the γ-ray energy of the M1(3/2^{+}â1/2^{+}) transition. In addition, three γ-ray peaks are observed and assigned as E2(5/2^{+}â1/2^{+}), E1(1/2^{-}â1/2^{+}), and E1(1/2^{-}â3/2^{+}) transitions. The excitation energies of the 5/2^{+} and 1/2^{-} states are determined to be 895.2±0.3(stat)±0.5(syst) and 1265.6±1.2(stat)_{-0.5}^{+0.7}(syst) keV, respectively. It is found that the ground state doublet spacing is well described by theoretical models based on existing s- and p-shell hypernuclear data.
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Differential cross sections and photon-beam asymmetries for the γ[over â]pâπ^{-}Δ^{++}(1232) reaction have been measured for 0.7
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Using data recorded with the Belle detector, we observe a new excited hyperon, an Ω^{*-} candidate decaying into Ξ^{0}K^{-} and Ξ^{-}K_{S}^{0} with a mass of 2012.4±0.7(stat)±0.6(syst) MeV/c^{2} and a width of Γ=6.4_{-2.0}^{+2.5}(stat)±1.6(syst) MeV. The Ω^{*-} is seen primarily in Ï(1S),Ï(2S), and Ï(3S) decays.
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BACKGROUND AND AIMS: Intracranial arterial stenosis (ICAS) is one of the most common causes of stroke, especially in Asians. Hyperuricemia has been associated with an increased risk of comorbidities such as metabolic syndrome or cardiovascular diseases. However, there are few studies focusing on the association between serum uric acid (SUA) levels and asymptomatic ICAS. The aim of this study was to explore the association between SUA and the prevalence of ICAS in middle-aged Korean health screening examinees. METHODS AND RESULTS: A cross-sectional study was performed on 9417 males and 7755 females who underwent a comprehensive health examination including transcranial Doppler (TCD) ultrasonography. The association of SUA and ICAS was analyzed using multivariate logistic regression. The prevalence of ICAS among the total examinee population was 3.55%. In females, the multivariate-adjusted odds ratio for ICAS was 1.52 (confidence interval 1.13-2.04) in the 3rd quartile of SUA and 1.45 (1.05-2.00) in the highest quartile, compared to the reference (P for trend 0.008). This trend was evident in all clinically relevant subgroups evaluated, including women with low inflammation status. SUA was not significantly associated with the prevalence of ICAS among males. In a sensitivity analysis, the multivariate-adjusted odds ratio of middle cerebral artery stenosis in females was 1.60 (1.09-2.37) in the highest quartile compared to the reference (P for trend 0.023). CONCLUSIONS: Higher SUA level was associated with increased risk of ICAS among middle-aged females but not males. A further cohort study is warranted to elucidate the effect of SUA on asymptomatic ICAS.
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Hiperuricemia/sangue , Doenças Arteriais Intracranianas/sangue , Ácido Úrico/sangue , Adulto , Doenças Assintomáticas , Biomarcadores/sangue , Comorbidade , Estudos Transversais , Feminino , Humanos , Hiperuricemia/diagnóstico , Hiperuricemia/epidemiologia , Doenças Arteriais Intracranianas/diagnóstico por imagem , Doenças Arteriais Intracranianas/epidemiologia , Masculino , Pessoa de Meia-Idade , Prevalência , República da Coreia/epidemiologia , Estudos Retrospectivos , Medição de Risco , Fatores de Risco , Ultrassonografia Doppler TranscranianaRESUMO
The study aims to evaluate the rate of transition to osteoporosis in 360 RA patients and estimate the rescreening intervals of bone mineral density (BMD) testing. Osteoporosis was newly developed in 24.8 % during mean follow-up of 7.4 years. The estimated time of a BMD testing interval was dependent on the baseline T-score in RA patients. INTRODUCTION: Although BMD testing is routinely performed in RA patients, the interval between BMD tests has not been determined. METHODS: We retrospectively recruited 360 consecutive female patients with RA, who underwent repeated BMD testing, with a mean age of 53.7 ± 10.2 years and a mean follow-up duration of 7.4 ± 5.0 years. We stratified the study participants into five groups based on their baseline T-score range. The testing interval was defined as the estimated time for 10 % of patients in each subgroup to transition to osteoporosis. Competing-risk analyses were performed with sensitivity analysis by menopausal status and risk factors for transition to osteoporosis. RESULTS: At baseline, 15 % of screened patients had osteoporosis, and during follow-up, that proportion increased to 24.8 %. The estimated BMD testing interval for 10 % of patients to develop osteoporosis was 9.6 years for those with normal BMD, 7.6 years for those with mild osteopenia, 4.7 years for those with moderate osteopenia, and 2.1 years for those with severe osteopenia. No significant risk factor for transition to osteoporosis was identified in this cohort. CONCLUSIONS: Our data indicate that osteoporosis will develop in less than 10 % of female RA patients during rescreening intervals of approximately 9 years for those with normal bone density at baseline, 7 years for those with mild osteopenia, 4 years for those with moderate osteopenia, and 2 years for those with severe osteopenia at baseline. BMD interval in RA patients could be adjusted according to their baseline BMD T-scores.
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Artrite Reumatoide/complicações , Densidade Óssea/fisiologia , Osteoporose/diagnóstico , Osteoporose/etiologia , Absorciometria de Fóton , Adulto , Idoso , Artrite Reumatoide/fisiopatologia , Doenças Ósseas Metabólicas/diagnóstico , Doenças Ósseas Metabólicas/etiologia , Doenças Ósseas Metabólicas/fisiopatologia , Progressão da Doença , Feminino , Seguimentos , Humanos , Programas de Rastreamento/organização & administração , Pessoa de Meia-Idade , Osteoporose/fisiopatologia , Estudos Retrospectivos , Medição de Risco/métodosRESUMO
The Ï-Λ(1520) interference effect in the γpâK^{+}K^{-}p reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between Ï and Λ(1520) production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when K^{+}K^{-} pairs are observed at forward angles but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the sqrt[s]=2.1 GeV bump structure in forward differential cross sections for Ï photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange, or rescattering processes via other hyperon states.
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The exclusive reaction γpâK(+)π(-)Σ(+) was measured for the first time using linearly polarized photons at beam energies from 1.85 to 2.96 GeV. Angular distributions in the rest frame of the K(+)π(-) system were fitted to extract spin-density matrix elements of the K(*0) decay. The measured parity spin asymmetry shows that natural-parity exchange is dominant in this reaction. This result clearly indicates the need for t-channel exchange of the κ(800) scalar meson.
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The RENO experiment has observed the disappearance of reactor electron antineutrinos, consistent with neutrino oscillations, with a significance of 4.9 standard deviations. Antineutrinos from six 2.8 GW(th) reactors at the Yonggwang Nuclear Power Plant in Korea, are detected by two identical detectors located at 294 and 1383 m, respectively, from the reactor array center. In the 229 d data-taking period between 11 August 2011 and 26 March 2012, the far (near) detector observed 17102 (154088) electron antineutrino candidate events with a background fraction of 5.5% (2.7%). The ratio of observed to expected numbers of antineutrinos in the far detector is 0.920±0.009(stat)±0.014(syst). From this deficit, we determine sin(2)2θ(13)=0.113±0.013(stat)±0.019(syst) based on a rate-only analysis.
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OBJECTIVE: T-cell immunoglobulin- and mucin-domain-containing molecule 3 (TIM-3) is a novel transmembrane protein that is involved in the regulation of T-helper 1 (Th1)-cell-mediated immunity. This study was undertaken to investigate the expressions of TIM-3 and its ligand galectin 9 (Gal-9) with respect to disease activity in rheumatoid arthritis (RA). METHODS: Blood was collected from 39 RA patients and 31 healthy controls. Blood leucocyte TIM-3 and Gal-9 mRNA levels and RA disease activity were determined. Synovial tissue (ST) from five RA patients and five osteoarthritis (OA) patients were examined for TIM-3 mRNA expression and were also analysed for TIM-3 by immunohistology. RESULTS: TIM-3 mRNA expression was significantly higher in the ST of RA patients than in the ST of OA patients. TIM-3 was expressed in the synovial sublining area in ST of RA patients but not in OA ST. TIM-3 mRNA expression from peripheral blood mononuclear cells (PBMCs) of RA patients was negatively correlated with the 28-joint Disease Activity Score (DAS28). Gal-9 mRNA level in PBMCs of RA patients was higher than in healthy controls, and was significantly higher in patients with low disease activity compared to those with moderate to high disease activity. Gal-9 mRNA expression in PBMCs of RA patients was positively correlated with forkhead box P3 (FoxP3) mRNA expression. CONCLUSION: TIM-3 and its interaction with Gal-9 are closely associated with RA disease activity and may play an important role in the pathogenesis of RA. In addition to the negative regulatory effect of Gal-9 mediated through the TIM-3-Gal-9 pathway, Gal-9 may exert its suppressive effect on RA disease activity by modulation of regulatory T (Treg) cells.