First Simultaneous Determination of Inclusive and Exclusive |V_{ub}|.

The first simultaneous determination of the absolute value of the Cabibbo-Kobayashi-Maskawa matrix element V_{ub} using inclusive and exclusive decays is performed with the full Belle data set at the ϒ(4S) resonance, corresponding to an integrated luminosity of 711 fb^{-1}. We analyze collision events in which one B meson is fully reconstructed in hadronic modes. This allows for the reconstruction of the hadronic X_{u} system of the semileptonic b→uℓν[over ¯]_{ℓ} decay. We separate exclusive B→πℓν[over ¯]_{ℓ} decays from other inclusive B→X_{u}ℓν[over ¯]_{ℓ} and backgrounds with a two-dimensional fit that utilizes the number of charged pions in the X_{u} system and the four-momentum transfer q^{2} between the B and X_{u} systems. Combining our measurement with information from lattice QCD and QCD calculations of the inclusive partial rate as well as external experimental information on the shape of the B→πℓν[over ¯]_{ℓ} form factor, we determine |V_{ub}^{excl}|=(3.78±0.23±0.16±0.14)×10^{-3} and |V_{ub}^{incl}|=(3.88±0.20±0.31±0.09)×10^{-3}, respectively, with the uncertainties being the statistical error, systematic errors, and theory errors. The ratio of |V_{ub}^{excl}|/|V_{ub}^{incl}|=0.97±0.12 is compatible with unity.

Search for a Heavy Neutrino in τ Decays at Belle.

We report on a search for a heavy Majorana neutrino in the decays τ^{-}→π^{-}ν_{h}, ν_{h}→π^{±}ℓ^{∓}, ℓ=e, µ. The results are obtained using the full data sample of 988 fb^{-1} collected with the Belle detector at the KEKB asymmetric energy e^{+}e^{-} collider, which contains 912×10^{6} ττ pairs. We observe no significant signal and set 95% CL upper limits on the couplings of the heavy right-handed neutrinos to the conventional standard model left-handed neutrinos in the mass range 0.2-1.6 GeV/c^{2}. This is the first study of a mixed couplings of heavy neutrinos to τ leptons and light-flavor leptons.

First Measurement of the Michel Parameter ξ

We report the first measurement of the Michel parameter ξ^{'} in the τ^{-}→µ^{-}ν[over ¯]_{µ}ν_{τ} decay with a new method proposed just recently. The measurement is based on the reconstruction of the τ^{-}→µ^{-}ν[over ¯]_{µ}ν_{τ} events with subsequent muon decay in flight in the Belle central drift chamber. The analyzed data sample of 988 fb^{-1} collected by the Belle detector corresponds to approximately 912×10^{6} τ^{+}τ^{-} pairs. We measure ξ^{'}=0.22±0.94(stat)±0.42(syst), which is in agreement with the standard model prediction of ξ^{'}=1. Statistical uncertainty dominates in this study, being a limiting factor, while systematic uncertainty is well under control. Our analysis proved the practicability of this promising method and its prospects for further precise measurement in future experiments.

Search for the Lepton Flavor Violating Decays B

We present a search for the lepton flavor violating decays B^{+}→K^{+}τ^{±}ℓ^{∓}, with ℓ=(e,µ), using the full data sample of 772×10^{6} BB[over ¯] pairs recorded by the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We use events in which one B meson is fully reconstructed in a hadronic decay mode. We find no evidence for B^{±}→K^{±}τℓ decays and set upper limits on their branching fractions at the 90% confidence level in the (1-3)×10^{-5} range. The obtained limits are the world's best results.

First Measurement of the B

We study B^{+}→π^{+}π^{0}π^{0} using 711 fb^{-1} of data collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We measure an inclusive branching fraction of (19.0±1.5±1.4)×10^{-6} and an inclusive CP asymmetry of (9.2±6.8±0.7)%, where the first uncertainties are statistical and the second are systematic, and a B^{+}→ρ(770)^{+}π^{0} branching fraction of (11.2±1.1±0.9_{-1.6}^{+0.8})×10^{-6}, where the third uncertainty is due to possible interference with B^{+}→ρ(1450)^{+}π^{0}. We present the first observation of a structure around 1 GeV/c^{2} in the π^{0}π^{0} mass spectrum, with a significance of 6.4σ, and measure a branching fraction to be (6.9±0.9±0.6)×10^{-6}. We also report a measurement of local CP asymmetry in this structure.

First Observation of Λπ

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}^{+}→Λπ^{+}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.

Evidence of a New Excited Charmed Baryon Decaying to Σ_{c}(2455)

We present the study of B[over ¯]^{0}→Σ_{c}(2455)^{0,++}π^{±}p[over ¯] decays based on 772×10^{6} BB[over ¯] events collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. The Σ_{c}(2455)^{0,++} candidates are reconstructed via their decay to Λ_{c}^{+}π^{∓} and Λ_{c}^{+} decays to pK^{-}π^{+}, pK_{S}^{0}, and Λπ^{+} final states. The corresponding branching fractions are measured to be B(B[over ¯]^{0}→Σ_{c}(2455)^{0}π^{+}p[over ¯])=(1.09±0.06±0.07)×10^{-4} and B(B[over ¯]^{0}→Σ_{c}(2455)^{++}π^{-}p[over ¯])=(1.84±0.11±0.12)×10^{-4}, which are consistent with the world average values with improved precision. A new structure is found in the M_{Σ_{c}(2455)^{0,++}π^{±}} spectrum with a significance of 4.2σ including systematic uncertainty. The structure is possibly an excited Λ_{c}^{+} and is tentatively named Λ_{c}(2910)^{+}. Its mass and width are measured to be (2913.8±5.6±3.8) MeV/c^{2} and (51.8±20.0±18.8) MeV, respectively. The products of branching fractions for the Λ_{c}(2910)^{+} are measured to be B(B[over ¯]^{0}→Λ_{c}(2910)^{+}p[over ¯])×B(Λ_{c}(2910)^{+}→Σ_{c}(2455)^{0}π^{+})=(9.5±3.6±1.6)×10^{-6} and B(B[over ¯]^{0}→Λ_{c}(2910)^{+}p[over ¯])×B(Λ_{c}(2910)^{+}→Σ_{c}(2455)^{++}π^{-})=(1.24±0.35±0.10)×10^{-5}. Here, the first and second uncertainties are statistical and systematic, respectively.

Measurement of Two-Particle Correlations of Hadrons in e

The measurement of two-particle angular correlation functions in high-multiplicity e^{+}e^{-} collisions at sqrt[s]=10.52 GeV is reported. In this study, the 89.5 fb^{-1} of hadronic e^{+}e^{-} annihilation data collected by the Belle detector at KEKB are used. Two-particle angular correlation functions are measured in the full relative azimuthal angle (Δϕ) and three units of pseudorapidity (Δη), defined by either the electron beam axis or the event-shape thrust axis, and are studied as a function of charged-particle multiplicity. The measurement in the thrust axis analysis, with mostly outgoing quark pairs determining the reference axis, is sensitive to the region of additional soft gluon emissions. No significant anisotropic collective behavior is observed with either coordinate analyses. Near-side jet correlations appear to be absent in the thrust axis analysis. The measurements are compared to predictions from various event generators and are expected to provide new constraints to the phenomenological models in the low-energy regime.

Search for a Light Higgs Boson in Single-Photon Decays of ϒ(1S) Using ϒ(2S)→π

We search for a light Higgs boson (A^{0}) decaying into a τ^{+}τ^{-} or µ^{+}µ^{-} pair in the radiative decays of ϒ(1S). The production of ϒ(1S) mesons is tagged by ϒ(2S)→π^{+}π^{-}ϒ(1S) transitions, using 158×10^{6} ϒ(2S) events accumulated with the Belle detector at the KEKB asymmetric energy electron-positron collider. No significant A^{0} signals in the mass range from the τ^{+}τ^{-} or µ^{+}µ^{-} threshold to 9.2 GeV/c^{2} are observed. We set the upper limits at 90% credibility level (C.L.) on the product branching fractions for ϒ(1S)→γA^{0} and A^{0}→τ^{+}τ^{-} varying from 3.8×10^{-6} to 1.5×10^{-4}. Our results represent an approximately twofold improvement on the current world best upper limits for the ϒ(1S)→γA^{0}(→τ^{+}τ^{-}) production. For A^{0}→µ^{+}µ^{-}, the upper limits on the product branching fractions for ϒ(1S)→γA^{0} and A^{0}→µ^{+}µ^{-} are at the same level as the world average limits, and vary from 3.1×10^{-7} to 1.6×10^{-5}. The upper limits at 90% credibility level on the Yukawa coupling f_{ϒ(1S)} and mixing angle sinθ_{A^{0}} are also given.

Impact of COVID-19 on Guillain-Barre Syndrome in India: A Multicenter Ambispective Cohort Study.

Introduction/Aims: Studies conducted during the coronavirus disease 2019 (COVID-19) pandemic have reported varied data regarding the incidence of Guillain-Barre syndrome (GBS). The present study investigated demographic and clinical features, management, and outcomes of patients with GBS during a specified period of the COVID-19 pandemic, and compared these features to those of GBS in the previous year. Methods: A multicenter, ambispective cohort study including 26 centers across India was conducted. Data from a pre-COVID-19 period (March 1 to August 31, 2019) were collected retrospectively and collected ambispectively for a specified COVID-19 period (March 1 to August 31, 2020). The study was registered with the Clinical Trial Registry India (CTRI/2020/11/029143). Results: Data from 555 patients were included for analysis: pre-COVID-19 (n = 334) and COVID-19 (n = 221). Males were more commonly affected during both periods (male:female, 2:1). Gastroenteritis was the most frequent antecedent event in 2019 (17.4%), whereas fever was the most common event in 2020 (10.7%). Paraparesis (21.3% versus [vs.] 9.3%, P = 0.001) and sensory involvement (51.1% vs. 41.3%; P = 0.023) were more common during COVID-19 in 2020, whereas back pain (26.3% vs. 18.4%; P = 0.032) and bowel symptoms (20.7% vs. 13.7%; P = 0.024) were more frequent in the pre-COVID period. There was no difference in clinical outcomes between the two groups in terms of GBS disability score at discharge and 3 months after discharge. Independent predictors of disability in the pre-COVID period included areflexia/hyporeflexia, the requirementfor intubation, and time to bulbar weakness; in the COVID-19 period, independent predictors included time from onset to admission, intubation, and intubation requirement. The mortality rate was 2.3% during the entire study period (13/555 cases). Discussion: Results of this study revealed an overall reduction in the frequency of GBS during the pandemic. The lockdown likely reduced the risk for antecedent infections due to social distancing and improved hygiene, which may have resulted in the reduction of the frequency of GBS.

Measurements of the Branching Fractions of the Semileptonic Decays Ξ_{c}

Using data samples of 89.5 and 711 fb^{-1} recorded at energies of sqrt[s]=10.52 and 10.58 GeV, respectively, with the Belle detector at the KEKB e^{+}e^{-} collider, we report measurements of branching fractions of semileptonic decays Ξ_{c}^{0}→Ξ^{-}ℓ^{+}ν_{ℓ} (ℓ=e or µ) and the CP-asymmetry parameter of Ξ_{c}^{0}→Ξ^{-}π^{+} decay. The branching fractions are measured to be B(Ξ_{c}^{0}→Ξ^{-}e^{+}ν_{e})=(1.31±0.04±0.07±0.38)% and B(Ξ_{c}^{0}→Ξ^{-}µ^{+}ν_{µ})=(1.27±0.06±0.10±0.37)%, and the decay parameter α_{Ξπ} is measured to be 0.63±0.03±0.01 with much improved precision compared with the current world average. The corresponding ratio B(Ξ_{c}^{0}→Ξ^{-}e^{+}ν_{e})/B(Ξ_{c}^{0}→Ξ^{-}µ^{+}ν_{µ}) is 1.03±0.05±0.07, which is consistent with the expectation of lepton flavor universality. The first measured asymmetry parameter A_{CP}=(α_{Ξ^{-}π^{+}}+α_{Ξ[over ¯]^{+}π^{-}})/(α_{Ξ^{-}π^{+}}-α_{Ξ[over ¯]^{+}π^{-}})=0.024±0.052±0.014 is found to be consistent with zero. The first and the second uncertainties above are statistical and systematic, respectively, while the third ones arise due to the uncertainty of the Ξ_{c}^{0}→Ξ^{-}π^{+} branching fraction.

Measurement of Differential Branching Fractions of Inclusive B→X_{u}ℓ

The first measurements of differential branching fractions of inclusive semileptonic B→X_{u}ℓ^{+}ν_{ℓ} decays are performed using the full Belle data set of 711 fb^{-1} of integrated luminosity at the ϒ(4S) resonance and for ℓ=e, µ. With the availability of these measurements, new avenues for future shape-function model-independent determinations of the Cabibbo-Kobayashi-Maskawa matrix element |V_{ub}| can be pursued to gain new insights in the existing tension with respect to exclusive determinations. The differential branching fractions are reported as a function of the lepton energy, the four-momentum-transfer squared, light-cone momenta, the hadronic mass, and the hadronic mass squared. They are obtained by subtracting the backgrounds from semileptonic B→X_{c}ℓ^{+}ν_{ℓ} decays and other processes, and corrected for resolution and acceptance effects.

2D and 3D radiographic outcome assessment of the effect of guided tissue regeneration using resorbable collagen membrane in the healing of through-and-through periapical lesions - a randomized controlled trial.

AIM: To evaluate the effect of collagen membrane on the healing of through-and-through periapical lesions using 2-dimensional (2D) and 3-dimensional (3D) imaging techniques. METHODOLOGY: Thirty-two patients with periapical radiolucencies measuring at least 10 mm and with confirmed loss of buccal and lingual cortical plates were randomly divided into GTR and control groups. Periapical surgery was performed in both groups, using a resorbable collagen membrane in the GTR group only. 2D healing was evaluated according to Molven's criteria, while 3D healing was assessed using modified PENN 3D criteria, RAC indices and the B index, 12 months after surgery. Data were analysed using Chi-square, Mann-Whitney and Wilcoxon signed rank tests. RESULTS: Thirty patients were analysed at the 12 months follow-up. Both groups had a significant reduction in the size of lesions [92 ± 12% (control) and 86 ± 14% (GTR) in 2D and 85 ± 19% (Control) and 82 ± 13% (GTR) in 3D], with no significant difference between the groups (P > 0.05). A total of 29(14 control, 15 GTR) teeth and 26(13 control, 13 GTR) teeth were classified as success according to Molven's (2D) and modified PENN 3D criteria, respectively, with no significant difference in success between 2D and 3D assessments. RAC indices of 3D images revealed the greatest percentage of complete healing in R scores (55% for Control, 41% for GTR), whereas cortical plate had the lowest percentage of healing (30% for Control, 27% for GTR) (P > 0.05). Only 2 (13%) patients in each group had complete healing using the B index. CONCLUSION: Periapical surgery with or without GTR was a predictable and viable solution for through-and-through lesions. There was no benefit in using a collagen membrane with regard to the outcome of periapical surgery in through-and-through lesions. Both cone beam computed tomography (CBCT) and periapical radiographs (PA) allowed similar assessment of healing after periapical surgery.

Prevalence of stroke in rural community--an overview of Indian experience.

Various prevalence studies of stroke conducted in different regions of rural India have been analyzed and compared with prevalence study of stroke in 51,165 rural population of Haryana. The prevalence of stoke varies in different regions of country and ranges from 40 to 270/100,000 rural population. The prevalence rates correspond to that in urban areas in same region but is much lower than stroke prevalence in metropolitan cities in India and from reported prevalence of 400-800/100,000 in Western countries. Ethnic, socio-economic and dietary factors may be responsible for this variance.