Observation of the Radiative Decays of ψ (1S) to χc1
We report the first observation of the radiative decay of the ψ(1S) into a charmonium state. The significance of the observed signal of ψ(1S)→γχc1 is 6.3 standard deviations including systematics. The branching fraction is calculated to be B[ψ(1S)→γχc1]=[4.7-1.8+2.4(stat)-0.5+0.4(sys)×10-5]. We also searched for ψ(1S) radiative decays into χc0,2 and ηc(1S,2S), and set upper limits on their branching fractions. These results are obtained from a 24.9 fb-1 data sample collected with the Belle detector at the KEKB asymmetric-energy e+e- collider at a center-of-mass energy equal to the ψ(2S) mass using ψ(1S) tagging by the ψ(2S)→ψ(1S)π+π- transitions. © 2020 authors. Published by the American Physical Society.
The approach proposed to classify commercial banks into banks that have a high probability of revoking a license and reliable banks, as well as an information and logical model for identifying a group of banks (or one bank) among reliable banks that are attractive for investment. The probability of license revocation was assessed using a logistic regression model based on database, consisting of 17559 observations for all banks, covering the period from Q1 2012 to Q4 2017. In view of the multicollinearity in data, RIDGE modification was applied with the algorithm for determining the penalty coefficient. In the model, the indicators of volatility of macroeconomic variables, expressed in the standard deviation and variance of the macroeconomic variable within the period under review, were included as regressors. The null hypothesis of statistical zero coefficients at volatility indicators of macroeconomic variables is rejected at various significance levels. The model is built in the R-studio programming environment using the «RIDGE» package. Based on the hierarchical clustering by the Ward method (as a measure of the distance — the square of the Euclidean distance) eleven clusters were obtained. In this paper, a brief description of these clusters is presented on the basis of the absolute mean values of the variables, as well as the relative average values of the bank's financial variables. Using the nonparametric Kruskal—Wallis criterion, which makes it possible to compare the average values for several groups simultaneously, it was found that the financial variables differ significantly at high levels of significance. The results of the cluster analysis can be used to support the investor's decision to select a cluster (or a bank within the cluster) to conduct stress testing of credit risk (as the largest source of losses) in order to invest in banks belonging to the selected cluster that have withstood stress testing. In the future, based on the results of stress testing of credit risk, it is possible to select from the analyzed cluster those banks that are the most resistant to stressful events and can later be viewed by the investor as investment objects.
In this paper, we propose an approach to take into account the impact of daily changing macroeconomic variables in the development of a model for the probability of revoking a license from Russian banks on the basis of their annual financial indicators. The essence of this approach is that to take into account the influence of macroeconomic variables it is proposed to use not the average value for the sample, but the median and the volatility characteristics: standard deviation and variance. Based on the annual financial performance of banks for the period from 2004 to 2015, as well as the values of macroeconomic variables, a logistic regression model for estimating the likelihood of license revocation from Russian banks was built. The volatility of macroeconomic variables is characterized by the variables "Standard deviation" and "Variance". The problem of eliminating multicollinearity between these variables is proposed to be solved by including in the model standardized values of the variable "Standard deviation" and their squares. An approach is proposed for determining the cutoff threshold in binary selection models, according to which the I and II types of errors are assigned different weights. In the function of determining the cut-off value, an external parameter α is introduced that characterizes the investor's attitude to the I type error (the operating bank is classified as a bank with a revoked license). Classification of banks into operating banks and banks with a revoked license is based on the obtained of the cut-off value, taking into account the selected value of α, at which the function of determining the cut-off value reaches a minimum.
Thus, the approach of taking into account the volatility indicators of macroeconomic variables proposed in the study made it possible to improve the quality of the model for forecasting the revocation of a license from a Russian bank. The model has a stronger predictive ability than models that take into account only the average values of the exchange rate of currencies and other macroeconomic variables.
The experimental results on the ratios of branching fractions R(D)=B(B→Dτ-ντ)/B(B→Dℓ-νℓ) and R(D∗)=B(B→D∗τ-ντ)/B(B→D∗ℓ-νℓ), where ℓ denotes an electron or a muon, show a long-standing discrepancy with the standard model predictions, and might hint at a violation of lepton flavor universality. We report a new simultaneous measurement of R(D) and R(D∗), based on a data sample containing 772×106 BB events recorded at the ϒ(4S) resonance with the Belle detector at the KEKB e+e- collider. In this analysis the tag-side B meson is reconstructed in a semileptonic decay mode and the signal-side τ is reconstructed in a purely leptonic decay. The measured values are R(D)=0.307±0.037±0.016 and R(D∗)=0.283±0.018±0.014, where the first uncertainties are statistical and the second are systematic. These results are in agreement with the standard model predictions within 0.2, 1.1, and 0.8 standard deviations for R(D), R(D∗), and their combination, respectively. This work constitutes the most precise measurements of R(D) and R(D∗) performed to date as well as the first result for R(D) based on a semileptonic tagging method. © 2020 authors.
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.