Search for B0 decays to invisible final states (+γ) at Belle
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)<7.8×10-5 and B(B0→invisible+γ)<1.6×10-5. © 2020 authors.
We report the measurement of γγ→ηc(1S),ηc(2S)→η′π+π- with η′ decays to γρ and ηπ+π- using 941 fb-1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The ηc(1S) mass and width are measured to be M=[2984.6±0.7 (stat)±2.2 (syst)±0.3 (model)] MeV/c2 and Γ=[30.8-2.2+2.3 (stat)±2.5 (syst)±1.4 (model)] MeV, respectively. First observation of ηc(2S)→η′π+π- with a significance of 5.5σ including systematic error is obtained, and the ηc(2S) mass is measured to be M=[3635.1±3.7 (stat)±2.9 (syst)±0.4 (model)] MeV/c2. The products of the two-photon decay width and branching fraction (B) of decays to η′π+π- are determined to be ΓγγΓγγB=[65.4±2.6 (stat)±7.8 (syst)] eV for ηc(1S) and [5.6-1.1+1.2 (stat)±1.1 (syst)] eV for ηc(2S). The cross sections for γγ→η′π+π- and η′f2(1270) are measured for the first time. © 2018 authors. Published by the American Physical Society.
Charmed hadrons are a unique probe of CP violation with up-type quarks. Yet, CPviolation in the charm sector is very suppressed by tiny CKM phases in the Standard Model. Any large non-zero measurement would thus be a sign of New Physics. We report on recent measurements of CP asymmetries in multibody charmed meson and baryon decays. The CP asymmetries are studied in regions of the Dalitz space.
We present the result of the search for the rare B meson decay of B+→+νγ with =e,μ. For the search the full data set recorded by the Belle experiment of 711 fb-1 integrated luminosity near the (4S) resonance is used. Signal candidates are reconstructed for photon energies Eγ larger than 1 GeV using a novel multivariate tagging algorithm. The novel algorithm fully reconstructs the second B meson produced in the collision using hadronic modes and was specifically trained to recognize the signal signature in combination with hadronic tag-side B meson decays. This approach greatly enhances the performance. Background processes that can mimic this signature, mainly charmless semileptonic decays and continuum processes, are suppressed using multivariate methods. The number of signal candidates is determined by analyzing the missing mass squared distribution as inferred from the signal side particles and the kinematic properties of the tag-side B meson. No significant excess over the background-only hypothesis is observed and upper limits on the partial branching fraction ΔB with Eγ>1 GeV individually for electron and muon final states as well as for the average branching fraction of both lepton final states are reported. We find a Bayesian upper limit of ΔB(B+→+νγ)<3.0×10-6 at 90% CL and also report an upper limit on the first inverse moment of the light-cone distribution amplitude of the B meson of λB>0.24 GeV at 90% CL. © 2018 authors. Published by the American Physical Society.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.