Measurement of the decays B → η ℓ ν ℓ and B → η ′ ℓ ν ℓ in fully reconstructed events at Belle

We report branching fraction measurements of the decays B+→ηℓ+νℓ and B+→η′ℓ+νℓ based on 711 fb−1 of data collected near the Υ(4S) resonance with the Belle experiment at the KEKB asymmetric-energy e+e− collider. This data sample contains 772 million B¯B events. One of the two Bmesons is fully reconstructed in a hadronic decay mode. Among the remaining (“signal-B”) daughters, we search for the η meson in two decay channels, η→γγ and η→π+π−π0, and reconstruct the η′meson in η′→ηπ+π− with subsequent decay of the η into γγ. Combining the two η modes and using an extended maximum likelihood, the B+→ηℓ+νℓ branching fraction is measured to be (4.2±1.1(stat.)±0.3(syst.))×10−5. For B+→η′ℓ+νℓ, we observe no significant signal and set an upper limit of 0.72×10−4 at 90% confidence level

Un estudio con médicos y enfermeras de una clínica privada de la ciudad de Santa Marta, Colombia

La presente investigación tuvo como propósito fundamental determinar el grado de relación existente entre el síndrome de Burnout y los factores de motivación laboral de los profesionales de la salud de una clínica privada del distrito de Santa Marta, basado metodológicamente en una investigación transversal no experimental de tipo correlacional. La muestra estuvo conformada por 73 personas distribuidas en 44 auxiliares enfermeras, 11 médicos y 18 enfermeras jefes a quienes se les aplicó los instrumentos Cuestionario de Motivación para el Trabajo CMT y Maslach Burnout Inventory (MBI-HSS). Los resultados obtenidos demuestran que no hay presencia de síndrome de Burnout y que el perfil motivacional predominante corresponde al de salario teniendo en cuenta las condiciones de motivación externa, además indican que no existe relación significativa entre las variables de los factores motivacionales para el trabajo y el Síndrome de Burnout. Los autores recomiendan aplicar estrategias de prevención del síndrome en los trabajadores de la salud, tales como mejoras en las retribuciones, capacitaciones, estímulos, y otros

Measurement of the branching fraction of the decay B+ →π+π-ℓ+νℓ in fully reconstructed events at Belle

We present an analysis of the exclusive B+→π+π-ℓ+νℓ decay, where ℓ represents an electron or a muon, with the assumption of charge-conjugation symmetry and lepton universality. The study exploits the full ϒ(4S) data sample collected by the Belle detector, corresponding to 711 fb-1 of integrated luminosity. Events are selected by fully reconstructing one B meson in hadronic decay modes, subsequently determining the properties of the other B meson. We extract the signal yields using a binned maximum-likelihood fit to the missing-mass squared distribution in bins of the invariant mass of the two pions or the momentum transfer squared. We measure a total branching fraction of B(B+→π+π-ℓ+νℓ)=[22.7-1.6+1.9(stat)±3.5(syst)]×10-5, where the uncertainties are statistical and systematic, respectively. This result is the first reported measurement of this decay

Measurement of B (Bs →dsX) with Bs semileptonic tagging

We report the first direct measurement of the inclusive branching fraction B(Bs→DsX) via Bs tagging in e+e-→ (5S) events. Tagging is accomplished through a partial reconstruction of semileptonic decays Bs→DsXℓν, where X denotes unreconstructed additional hadrons or photons and ℓ is an electron or muon. With 121.4 fb-1 of data collected at the (5S) resonance by the Belle detector at the KEKB asymmetric-energy e+e- collider, we obtain B(Bs→DsX)=(60.2±5.8±2.3)%, where the first uncertainty is statistical and the second is systematic

Test of lepton flavor universality and search for lepton flavor violation in B → Kℓℓ decays

We present measurements of the branching fractions for the decays B → Kμ+μ− and B → Ke+e−, and their ratio (RK), using a data sample of 711 fb−1 that contains 772 × 106BB¯ events. The data were collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. The ratio RK is measured in five bins of dilepton invariant-mass-squared (q2): q2 ∈ (0.1, 4.0), (4.00, 8.12), (1.0, 6.0), (10.2, 12.8) and (\u3e 14.18) GeV2/c4, along with the whole q2 region. The RK value for q2 ∈ (1.0, 6.0) GeV2/c4 is 1.03−0.24+0.28 ± 0.01. The first and second uncertainties listed are statistical and systematic, respectively. All results for RK are consistent with Standard Model predictions. We also measure CP-averaged isospin asymmetries in the same q2 bins. The results are consistent with a null asymmetry, with the largest difference of 2.6 standard deviations occurring for the q2 ∈ (1.0, 6.0) GeV2/c4 bin in the mode with muon final states. The measured differential branching fractions, dℬ /dq2, are consistent with theoretical predictions for charged B decays, while the corresponding values are below the expectations for neutral B decays. We have also searched for lepton-flavor-violating B → Kμ±e∓ decays and set 90% confidence-level upper limits on the branching fraction in the range of 10−8 for B+ → K+μ±e∓, and B0 → K0μ±e∓ modes. [Figure not available: see fulltext.

First determination of the spin and parity of the charmed-strange baryon Ξc (2970)+

We report results from a study of the spin and parity of Ξc(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+→Ξc+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)+→Ξc′0π+]=1.67±0.29(stat)-0.09+0.15(syst)±0.25(IS), where the last uncertainty is due to possible isospin-symmetry-breaking effects. This R value favors the spin-parity JP=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

Measurement of the Branching Fraction of the Decay B+→π+π−ℓ+νℓ\boldsymbol{B^{+}\to\pi^{+}\pi^{-}\ell^{+}\nu_\ell} in Fully Reconstructed Events at Belle

We present an analysis of the exclusive $B^{+}\to\pi^{+}\pi^{-}\ell^{+}\nu_{\ell}$ decay, where $\ell$ represents an electron or a muon, with the assumption of charge-conjugation symmetry and lepton universality. The analysis uses the full $\Upsilon(4S)$ data sample collected by the Belle detector, corresponding to 711 fb$^{-1}$ of integrated luminosity. We select the events by fully reconstructing one $B$ meson in hadronic decay modes, subsequently determining the properties of the other $B$ meson. We extract the signal yields using a binned maximum-likelihood fit to the missing-mass squared distribution in bins of the invariant mass of the two pions or the momentum transfer squared. We measure a total branching fraction of ${{\cal B}(B^{+}\to \pi^{+}\pi^{-}\ell^{+}\nu_{\ell})= [22.7 ^{+1.9}_{-1.6} (\mathrm{stat}) \pm 3.5(\mathrm{syst}) ]\times 10^{-5}}$, where the uncertainties are statistical and systematic, respectively. This result is the first reported measurement of this decay.Comment: 23 pages, 19 figure

First search for the η\u3csub\u3ec2\u3c/sub\u3e(1D) in B decays at Belle

© 2020, The Author(s). The first dedicated search for the ηc2(1D) is carried out using the decays B+→ ηc2(1D)K+, B0 → ηc2(1D)KS0, B0→ ηc2(1D)π−K+, and B+→ ηc2(1D)π+KS0 with ηc2(1D) → hcγ. No significant signal is found. For the ηc2(1D) mass range between 3795 and 3845 MeV/c2, the branching-fraction upper limits are determined to be ℬ(B+→ ηc2(1D)K+) × ℬ(ηc2(1D) → hcγ) \u3c 3.7 × 10−5, ℬ(B0→ ηc2(1D)K0) × ℬ(ηc2(1D) → hcγ) \u3c 3.5 × 10−5, ℬ(B0→ ηc2(1D)π−K+) × ℬ(ηc2(1D) → hcγ) \u3c 1.0 × 10−4, and ℬ(B+→ ηc2(1D)π+KS0) × ℬ(ηc2(1D) → hcγ) \u3c 1.1 × 10−4 at 90% C.L. The analysis is based on the 711 fb−1 data sample collected on the ϒ(4S) resonance by the Belle detector, which operated at the KEKB asymmetric-energy e+e− collider. [Figure not available: see fulltext.

Search for B0 decays to invisible final states (+γ) at Belle

© 2020 authors. We report searches for B0→invisible and B0→invisible+γ decays, where the energy of the photon is required to be larger than 0.5 GeV. These results are obtained from a 711 fb-1 data sample that contains 772×106BB¯ pairs and was collected near the ϒ(4S) resonance with the Belle detector at the KEKB e+e- collider. We observe no significant signal for either decay and set upper limits on their branching fractions at 90% confidence level of B(B0→invisible)\u3c7.8×10-5 and B(B0→invisible+γ)\u3c1.6×10-5

Search for ω (2012) →k Ξ (1530) →kπ Ξ at Belle

© 2019 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article\u27s title, journal citation, and DOI. Funded by SCOAP 3 . Using data samples of e+e- collisions collected at the I(1S), I(2S), and I(3S) resonances with the Belle detector, we search for the three-body decay of the ω(2012) baryon to KπΞ. This decay is predicted to dominate for models describing the ω(2012) as a KΞ(1530) molecule. No significant ω(2012) signals are observed in the studied channels, and 90% credibility level upper limits on the ratios of the branching fractions relative to KΞ decay modes are obtained