Search for a doubly-charged DDK bound state in Υ(1S,2S) inclusive decays and via direct production in e+e− collisions at s√ = 10.520, 10.580, and 10.867 GeV
We report the results of a first search for a doubly-charged DDK bound state, denoted the R++, in Υ(1S) and Υ(2S) inclusive decays and via direct production in e+e− collisions at s√ = 10.520, 10.580, and 10.867 GeV. The search uses data accumulated with the Belle detector at the KEKB asymmetric-energy e+e− collider. No significant signals are observed in the D+D∗+s invariant-mass spectra of all studied modes. The 90\% credibility level upper limits on their product branching fractions in Υ(1S) and Υ(2S) inclusive decays (B(Υ(1S,2S)→R+++anything)×B(R++→D+D∗+s)), and the product values of Born cross section and branching fraction in e+e− collisions (σ(e+e−→R+++anything)×B(R++→D+D∗+s)) at s√ = 10.520, 10.580, and 10.867 GeV under different assumptions of R++ masses varying from 4.13 to 4.17 GeV/c2, and widths varying from 0 to 5 MeV are obtained.
A search for the lepton-flavour violating decay D0 → e ±µ ∓ is made with a dataset corresponding to an integrated luminosity of 3.0 fb−1 of proton-proton collisions at centre-of-mass energies of 7 TeV and 8 TeV, collected by the LHCb experiment. Candidate D0 mesons are selected using the decay D∗+ → D0π + and the D0 → e ±µ ∓ branching fraction is measured using the decay mode D0 → K−π + as a normalisation channel. No significant excess of D0 → e ±µ ∓ candidates over the expected background is seen, and a limit is set on the branching fraction, B(D0 → e ±µ ∓) < 1.3×10−8 , at 90% confidence level. This is an order of magnitude lower than the previous limit and it further constrains the parameter space in some leptoquark models and in supersymmetric models with R-parity violation.
The 25th International Conference on Computing in High Energy and Nuclear Physics (CHEP), organised by CERN, took place as a virtual event from 17–21 May 2021. The conference attracted 1144 registered participants from 46 different countries. There were 207 scientific presentations made over the 5 days of the conference. These were divided between 30 long talks and 2 keynotes, which were presented in plenary sessions; and 175 short talks, which were presented in parallel sessions.
During LHC Run 1, the LHCb experiment recorded around 1011 collision events. This paper describes Event Index — an event search system. Its primary function is to quickly select subsets of events from a combination of conditions, such as the estimated decay channel or number of hits in a subdetector. Event Index is essentially Apache Lucene  optimized for read-only indexes distributed over independent shards on independent nodes.
Simulation is one of the key components in high energy physics. Historically it relies on the Monte Carlo methods which require a tremendous amount of computation resources. These methods may have difficulties with the expected High Luminosity Large Hadron Collider need, so the experiment is in urgent need of new fast simulation techniques. The application of Generative Adversarial Networks is a promising solution to speed up the simulation while providing the necessary physics performance. In this paper we propose the Self-Attention Generative Adversarial Network as a possible improvement of the network architecture. The application is demonstrated on the performance of generating responses of the LHCb type of the electromagnetic calorimeter.
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.