Using the entire Belle data sample of 980 fb−1 of e+e− collisions, we present the results of a study of excited Ωc charmed baryons in the decay mode Ξc+K−. We show confirmation of four of the five ...narrow states reported by the LHCb Collaboration: the Ωc(3000), Ωc(3050), Ωc(3066), and Ωc(3090).
Here, we present a measurement of angular observables and a test of lepton flavor universality in the B → K*ℓ+ℓ- decay, where ℓ is either e or μ . The analysis is performed on a data sample ...corresponding to an integrated luminosity of 711fb-1 containing 772×106 B B ¯ pairs, collected at the Υ ( 4S ) resonance with the Belle detector at the asymmetric-energy e+e- collider KEKB. The finding is consistent with standard model (SM) expectations, where the largest discrepancy from a SM prediction is observed in the muon modes with a local significance of 2.6σ .
We present the first measurements of the absolute branching fractions of Ξc+ decays into Ξ−π+π+ and pK−π+ final states. Our analysis is based on a data set of (772±11)×106 BB¯ pairs collected at the ...ϒ(4S) resonance with the Belle detector at the KEKB e+e− collider. We measure the absolute branching fraction of B¯0→Λ¯c−Ξc+ with the Ξc+ recoiling against Λ¯c− in B¯0 decays resulting in B(B¯0→Λ¯c−Ξc+)=1.16±0.42(stat.)±0.15(syst.)×10−3. We then measure the product branching fractions B(B¯0→Λ¯c−Ξc+)B(Ξc+→Ξ−π+π+) and B(B¯0→Λ¯c−Ξc+)B(Ξc+→pK−π+). Dividing these product branching fractions by B¯0→Λ¯c−Ξc+ yields B(Ξc+→Ξ−π+π+)=2.86±1.21(stat.)±0.38(syst.)% and B(Ξc+→pK−π+)=0.45±0.21(stat.)±0.07(syst.)%. Our result for B(Ξc+→Ξ−π+π+) can be combined with Ξc+ branching fractions measured relative to Ξc+→Ξ−π+π+ to set the absolute scale for many Ξc+ branching fractions.
We report the result for a search for the leptonic decay of B+→μ+νμ using the full Belle dataset of 711 fb−1 of integrated luminosity at the ϒ(4S) resonance. In the Standard Model leptonic B-meson ...decays are helicity and Cabibbo-Kobayashi-Maskawa suppressed. To maximize sensitivity an inclusive tagging approach is used to reconstruct the second B meson produced in the collision. The directional information from this second B meson is used to boost the observed μ into the signal B-meson rest frame, in which the μ has a monochromatic momentum spectrum. Though its momentum is smeared by the experimental resolution, this technique improves the analysis sensitivity considerably. Analyzing the μ momentum spectrum in this frame we find B(B+→μ+νμ)=(5.3±2.0±0.9)×10−7 with a one-sided significance of 2.8 standard deviations over the background-only hypothesis. This translates to a frequentist upper limit of B(B+→μ+νμ)<8.6×10−7 at 90% confidence level. The experimental spectrum is then used to search for a massive sterile neutrino, B+→μ+N, but no evidence is observed for a sterile neutrino with a mass in a range of 0–1.5 GeV. The determined B+→μ+νμ branching fraction limit is further used to constrain the mass and coupling space of the type II and type III two-Higgs-doublet models.
We report measurements of the production cross sections of charged pions, kaons, and protons as a function of fractional energy, the event-shape variable called thrust, and the transverse momentum ...with respect to the thrust axis. These measurements access the transverse momenta created in the fragmentation process, which are of critical importance to the understanding of any transverse-momentum-dependent distribution and fragmentation functions. The low transverse-momentum part of the cross sections can be well described by Gaussians in transverse momentum as is generally assumed but the fractional-energy dependence is nontrivial and different hadron types have varying Gaussian widths. The width of these Gaussians decreases with thrust and shows an initially rising, then decreasing fractional-energy dependence. The widths for pions and kaons are comparable within uncertainties, while those for protons are significantly narrower. These single-hadron cross sections and Gaussian widths are obtained from a 558 fb−1 data sample collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider.
We report results from a study of the spin and parity of Ξ c ( 2970 ) + using a 980 fb −1 data sample collected by the Belle detector at the KEKB asymmetric-energy e+e− collider. The decay angle ...distributions in the chain Ξc (2970)+→ Ξc (2645) 0π+ → Ξ+c π− π+ are analyzed to determine the spin of this charmed-strange baryon. The angular distributions strongly favor the Ξc (2970)+ spin J = 1/2 over 3/2 or 5/2, under an assumption that the lowest partial wave dominates in the decay. We also measure the ratio of Ξc (2970)+ decay branching fractions R = B Ξc (2970)+ → Ξc (2645)0π+/B Ξc (2970)+ → Ξ0c π+ = 1.67 ± 0.29 (stat)+0.15 −0.09 (syst) ± 0.25 (IS), where the last uncertainty is due to possible isospin-symmetry-breaking effects. This R value favors the spin-parity J P = 1/2+ with the spin of the light-quark degrees of freedom sl = 0. This is the first determination of the spin and parity of a charmed-strange baryon.
Study on chromosomes of fish has become a priority area of research in recent years. Chromosome analysis can be useful for addressing a variety of evolutionary and genetic questions about fishes. The ...global fish fauna consists of about 28,900 species of fishes of which 2,200 species are cytogenetically studied. India's contribution so far was around 220 species. Fish chromosome studies of freshwater fishes are further sporadic in Orissa. Therefore, the present study is proposed for a systematic cytogenetic investigation of some freshwater fishes of Orissa. Karyotypic study of 5 species namely Labeo fimbriatus (Fam. Cyprinidae), Puntius sophore (Fam. Cyprinidae), Osteobrama cotio cotio (Fam. Cyprinidae), Chanda nama (Fam. Chandidae), and, Xenentodon cancila (Fam. Benonidae) from rural ponds of Bhubaneswar, India, was carried out. The diploid chromosome number in Labeo fimbriatus was 50 with a chromosomal formula of 10m+10sm+30T (FN=70), Puntius sophore 2n=48, 2m+46T (FN=50), Osteobrama cotio cotio 2n=54, 10m+8sm+8st+28T (FN=72), Chanda nama 2n=50, 8m+6sm+10st+26T (FN=64) and Xenentodon cancila, 2n=48 with chromosomal formula of 22m+10sm+6st+10T (FN=80). The evolutionary significance of these karyotypes of 5 species has been discussed.
We report the first observation of the decay Λ+c→pK+π- using a 980 fb-1 data sample collected by the Belle detector at the KEKB asymmetric-energy e+e- collider. This is the first observation of a ...doubly Cabibbo-suppressed decay of a charmed baryon. We measure the branching ratio of this decay with respect to its Cabibbo-favored counterpart to be B(Λ+c→pK+π-)/B(Λ+c→pK-π+)=(2.35±0.27±0.21)×10-3, where the uncertainties are statistical and systematic, respectively.
We measure the inclusive production cross sections of hyperons and charmed baryons from e+e− annihilation using a 800 fb−1 data sample taken near the ϒ(4S) resonance with the Belle detector at the ...KEKB asymmetric-energy e+e− collider. The feed-down contributions from heavy particles are subtracted using our data, and the direct production cross sections are presented for the first time. The production cross sections divided by the number of spin states for S=−1 hyperons follow an exponential function with a single slope parameter except for the Σ(1385)+ resonance. Suppression for Σ(1385)+ and Ξ(1530)0 hyperons is observed. Among the production cross sections of charmed baryons, a factor of 3 difference for Λc+ states over Σc states is observed. This observation suggests a diquark structure for these baryons.
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