Search for B- →μ- ν μ Decays at the Belle Experiment
We report the results of a search for the rare, purely leptonic decay B-→μ-ν μ performed with a 711 fb-1 data sample that contains 772×106 BB pairs, collected near the (4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. The signal events are selected based on the presence of a high momentum muon and the topology of the rest of the event showing properties of a generic B-meson decay, as well as the missing energy and momentum being consistent with the hypothesis of a neutrino from the signal decay. We find a 2.4 standard deviation excess above background including systematic uncertainties, which corresponds to a branching fraction of B(B-→μ-νμ)=(6.46±2.22±1.60)×10-7 or a frequentist 90% confidence level interval on the B-→μ-ν μ branching fraction of [2.9,10.7]×10-7. © 2018 authors. Published by the American Physical Society.
This proceeding volume contains selected contributions from the participants of the IV International Young Researchers Conference: Physics, Technologies and Innovation (PTI-2017) held from May 15 to 19, 2017 in Ekaterinburg, Russia. The conference continued the tradition of annual meetings in the general area of modern science and innovative technology. This, fourth, conference was organized and held by the Institute of Physics and Technology of the Ural Federal University, one of the largest educational institutions in Russia. The primary aim of the conference was providing the opportunity for younger researchers (of graduate and postgraduate level) to meet and discuss the results of their studies, and to present their work in front of a panel of national and international experts. To encourage graduate and postgraduate students to attend and make the meeting as accessible as possible, the conference this year, same as previously, was totally free of charge for all the participants.
A direct search for lepton flavour violating decays of the Higgs boson (H) in the H→eτand H→eμ channels is described. The data sample used in the search was collected in proton–proton collisions at with the CMS detector at the LHC and corresponds to an integrated luminosity of 19.7 fb−1. No evidence is found for lepton flavour violating decays in either final state. Upper limits on the branching fractions, B(H→eτ)<0.69%and B(H→eμ)<0.035%, are set at the 95% confidence level. The constraint set onB(H→eτ) is an order of magnitude more stringent than the existing indirect limits. The limits are used to constrain the corresponding flavour violating Yukawa couplings, absent in the standard model.
The article is devoted to the problem of interpreting the concept of time in the context of some concepts of modern physics. This fundamental concept inevitably arises in physical theories, but there is still no adequate description of it in the philosophy of science. In the theory of relativity, quantum field theory, the standard model of elementary particle physics, the theory of loop quantum gravity, superstring theory, and other recent theories, the idea of time is explicitly or implicitly present. Sometimes, as, for example, in the special theory of relativity, it plays a pronounced role, sometimes not, but somehow it is and is implied by the content of the theory and in some cases by its mathematical apparatus. Especially important for solving the problem is the fundamental difference between the space-time processes of the microcosm and the macrocosm. In this connection, there is a need to understand time as it appears in modern physics, its description in the language of philosophy (there is also no satisfactory mathematical apparatus for describing time). This will make it possible to get closer to the answer to the question about the properties of time and, if not answered, then formulate the correct question about what it is. To this end, this study analyzes the key concepts of modern physics, taking into account the historical-scientific and historical-philosophical perspectives, which in some cases allows us to detect the continuity of ideas related to the understanding of time, their development, as well as the emergence of fundamentally new ones. In the course of the analysis, the characteristics of time that are correct from the point of view of physical theory are formulated, and an attempt is made to raise the question of the nature of time. Based on the work done, conclusions are drawn about the current state of the problem and the prospects for its solution.
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.
This book presents invited reviews and original short notes of recent results obtained in studies concerning the fabrication and application of nanostructures, which hold great promise for the next generation of electronic, optoelectronic and energy conversion devices.
Covering exciting and relatively new topics such as fast-progressing nanoelectronics and optoelectronics, molecular electronics and spintronics, nanophotonics, nanosensorics and nanoenergetics as well as nanotechnology and quantum processing of information, this book gives readers a more complete understanding of the practical uses of nanotechnology and nanostructures.
We consider the “Matthew effect” in the citation process which leads to reallocation (or misallocation) of the citations received by scientific papers within the same journals. The case when such reallocation correlates with a country where an author works is investigated. Russian papers in chemistry and physics published abroad were examined. We found that in both disciplines in about 60% of journals Russian papers are cited less than average ones. However, if we consider each discipline as a whole, citedness of a Russian paper in physics will be on the average level, while chemistry publications receive about 16% citations less than one may expect from the citedness of the journals where they appear. Moreover, Russian chemistry papers mostly become undercited in the leading journals of the field. Characteristics of a “Matthew index” indicator and its significance for scientometric studies are also discussed.
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.