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Measurement of the Charm-Mixing Parameter yCP
Physical Review Letters. 2019. Vol. 122. No. 1. P. 1-10.
Derkach D., Hushchyn M., Kazeev N., Ratnikov F., Arzymatov K., Borisyak M., Chekalina V., Ustyuzhanin A.
A measurement of the charm-mixing parameter yCP using D0 → KþK−, D0 → πþπ−, and D0 → K−πþ decays is reported. The D0 mesons are required to originate from semimuonic decays of B− and B0 mesons. These decays are partially reconstructed in a data set of proton-proton collisions at center-of-mass energies of 7 and 8 TeV collected with the LHCb experiment and corresponding to an integrated luminosity of 3 fb−1. The yCP parameter is measured to be ð0.57 0.13ðstatÞ 0.09ðsystÞÞ%, in agreement with, and as precise as, the current world-average value.
M. Borisyak, N. Kazeev, Journal of Instrumentation 2019 Vol. 14 No. 08 P. 1-8
Data analysis in high energy physics often deals with data samples consisting of a mixture of signal and background events. The sPlot technique is a common method to subtract the contribution of the background by assigning weights to events. Part of the weights are by design negative. Negative weights lead to the divergence of some ...
Added: August 20, 2019
Derkach D., Hushchyn M., Kazeev N. et al., Journal of High Energy Physics 2019 Vol. 2019 No. 2 P. 1-33
A search for CP violation in the Cabibbo-suppressed D0 → K+K−π+π− decay mode is performed using an amplitude analysis. The measurement uses a sample of pp collisions recorded by the LHCb experiment during 2011 and 2012, corresponding to an integrated luminosity of 3.0 fb−1. The D0 mesons are reconstructed from semileptonic b-hadron decays into D0μ−X final states. The selected sample contains more than 160 000 signal decays, allowing ...
Added: March 17, 2019
Derkach D., Hushchyn M., Likhomanenko T. et al., Journal of Physics: Conference Series 2018 Vol. 1085 No. 4 P. 1-5
One of the most important aspects of data analysis at the LHC experiments is the particle identification (PID). In LHCb, several different sub-detectors provide PID information: two Ring Imaging Cherenkov (RICH) detectors, the hadronic and electromagnetic calorimeters, and the muon chambers. To improve charged particle identification, we have developed models based on deep learning and ...
Added: October 18, 2018
Ryzhikov A., Ustyuzhanin A., Journal of Physics: Conference Series 2018 Vol. 1085 P. 1-6
In the research, a new approach for finding rare events in high-energy physics was tested. As an example of physics channel the decay of \tau -> 3 \mu is taken that has been published on Kaggle within LHCb-supported challenge. The training sample consists of simulated signal and real background, so the challenge is to train ...
Added: December 11, 2017
Hushchyn M., Chekalina V., , in : Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. Frontier Detectors for Frontier Physics: 14th Pisa Meeting on Advanced Detectors. : Elsevier, 2019. P. 568-569.
One of the most challenging data analysis tasks of modern High Energy Physics experiments is the identification of particles. In this proceedings we review the new approaches used for particle identification at the LHCb experiment. Machine-Learning based techniques are used to identify the species of charged and neutral particles using several observables obtained by the ...
Added: February 19, 2020
Hushchyn M., Derkach D., Ustyuzhanin A. et al., Nature Physics 2017 Vol. 13 P. 391-396
Differences in the behaviour of matter and antimatter have been observed in K and B meson decays, but not yet in any baryon decay. Such differences are associated with the non-invariance of fundamental interactions under the combined charge-conjugation and parity transformations, known as CP violation. Here, using data from the LHCb experiment at the Large Hadron Collider, we search for CP-violating asymmetries ...
Added: January 30, 2018
Association for Computing Machinery (ACM), 2018
Added: December 27, 2019
Derkach D., Hushchyn M., Kazeev N. et al., Physical Review Letters 2019 Vol. 123 No. 3 P. 1-11
The radiative decay Λ0b→Λγ is observed for the first time using a data sample of proton-proton collisions corresponding to an integrated luminosity of 1.7 fb−1 collected by the LHCb experiment at a center-of-mass energy of 13 TeV. Its branching fraction is measured exploiting the B0→K*0γ decay as a normalization mode and is found to be B(Λ0b→Λγ)=(7.1±1.5±0.6±0.7)×10−6, where the quoted uncertainties are statistical, systematic, and ...
Added: March 16, 2020
Smetanin S., Proceedings of the Institute for System Programming of the RAS 2017 Vol. 29 No. 4 P. 315-324
With the popularization of social media, a vast amount of textual content with additional geo-located and time-stamped information is directly generated by human every day. Both tweet meaning and extended message information can be analyzed in a purpose of exploration of public mood variations within a certain time periods.
This paper aims at describing the development ...
Added: November 23, 2018
Borisyak M., Kazeev N., Journal of Physics: Conference Series 2020 Vol. 1525 Article 012088
Data analysis in high energy physics has to deal with data samples produced from different sources. One of the most widely used ways to unfold their contributions is the sPlot technique. It uses the results of a maximum likelihood fit to assign weights to events. Some weights produced by sPlot are by design negative. Negative ...
Added: October 5, 2021
Hushchyn M., Derkach D., Ustyuzhanin A. et al., Physics Letters B 2018 Vol. 777 P. 16-30
Measurements of CP observables in B±→D(⁎)K± and B±→D(⁎)π± decays are presented, where D(⁎) indicates a neutral D or D⁎ meson that is an admixture of D(⁎)0 and D¯(⁎)0states. Decays of the D⁎ meson to the Dπ0 and Dγ final states are partially reconstructed without inclusion of the neutral pion or photon, resulting in distinctive shapes in the Bcandidate invariant mass distribution. Decays of the D meson are fully reconstructed in the K±π∓, K+K− and π+π− final states. The analysis uses a sample of charged B mesons ...
Added: January 30, 2018
A. Maevskiy, F. Ratnikov, Zinchenko A. et al., The European Physical Journal C - Particles and Fields 2021 Vol. 81 Article 599
High energy physics experiments rely heavily on the detailed detector simulation models in many tasks. Running these detailed models typically requires a notable amount of the computing time available to the experiments. In this work, we demonstrate a new approach to speed up the simulation of the Time Projection Chamber tracker of the MPD experiment at ...
Added: July 12, 2021
Ustyuzhanin A., Likhomanenko T., Derkach D. et al., Journal of Instrumentation 2016 Vol. 11
A new algorithm for the determination of the initial flavour of B0 s mesons is presented. The algorithm is based on two neural networks and exploits the b hadron production mechanism at a hadron collider. The first network is trained to select charged kaons produced in association with the B0 s meson. The second network ...
Added: October 23, 2016
Cham : Springer, 2019
This book constitutes the post-conference proceedings of the 4th International Conference on Machine Learning, Optimization, and Data Science, LOD 2018, held in Volterra, Italy, in September 2018.The 46 full papers presented were carefully reviewed and selected from 126 submissions. The papers cover topics in the field of machine learning, artificial intelligence, reinforcement learning, computational optimization and data ...
Added: October 17, 2019
Derkach D., Borisyak M., Ustyuzhanin A. et al., Physics Letters B 2016 No. 762 P. 253-262
A time-dependent angular analysis of Bs0→ψ(2S)ϕ decays is performed using data recorded by the LHCb experiment. The data set corresponds to an integrated luminosity of 3.0fb−1 collected during Run 1 of the LHC. The CP -violating phase and decay-width difference of the Bs0 system are measured to be ϕs=0.23−0.28+0.29±0.02rad and ΔΓs=0.066−0.044+0.041±0.007ps−1 , respectively, where the ...
Added: October 21, 2016
Ustyuzhanin A., Likhomanenko T., Derkach D. et al., Journal of High Energy Physics 2016
The decays Λb0 → ψ(2S)pK− and Λb0 → J/ψπ+π−pK− are observed in a data sample corresponding to an integrated luminosity of 3 fb−1, collected in proton-proton collisions at 7 and 8 TeV centre-of-mass energies by the LHCb detector. The ψ(2S) mesons are reconstructed through the decay modes ψ(2S) → μ+μ− and ψ(2S) → J/ψπ+π−.
The branching fractions relative to that of Λb0 → J/ψpK− are measured to be
M(Λ0b)=5619.65±0.17±0.17 MeV/c2,M(Λb0)=5619.65±0.17±0.17 MeV/c2, ...
Added: October 23, 2016
V.Belavin, A.Filatov, A.Ustyuzhanin et al., Journal of Physics: Conference Series 2018 Vol. 1085 No. 4 P. 042025-1-042025-6
Traces of electro-magnetic showers in the neutrino experiments may be considered as signals of dark-matter particles. For example, SHiP experiment is going to use emulsion film detectors similar to the ones designed for OPERA experiment from dark matter search. The goal of this research is to develop an algorithm that can identify traces of electro-magnetic ...
Added: December 8, 2017
Borisyak M., Belous M., Derkach D. et al., Journal of Instrumentation 2017
High-energy physics experiments rely on reconstruction of the trajectories of particles produced at the interaction point. This is a challenging task, especially in the high track multiplicity environment generated by p-p collisions at the LHC energies. A typical event includes hundreds of signal examples (interesting decays) and a significant amount of noise (uninteresting examples). This ...
Added: October 18, 2017
Borisyak M., Ustyuzhanin A., Derkach D. et al., Journal of Physics: Conference Series 2017 No. 898 P. 1-7
High-energy physics experiments rely on reconstruction of the trajectories of particles produced at the interaction point. This is a challenging task, especially in the high track multiplicity environment generated by p-p collisions at the LHC energies. A typical event includes hundreds of signal examples (interesting decays) and a significant amount of noise (uninteresting examples). This ...
Added: June 16, 2017
Borisyak M., Усвятцов М., Mulhearn M. J. et al., Journal of Physics: Conference Series 2017 Vol. 3 No. 898 P. 1-8
The CRAYFIS experiment proposes to use privately owned mobile phones as a ground detector array for Ultra High Energy Cosmic Rays. Upon interacting with Earth’s atmosphere, these events produce extensive particle showers which can be detected by cameras on mobile phones. A typical shower contains minimally-ionizing particles such as muons. As these particles interact with ...
Added: June 16, 2017
Derkach D., Hushchyn M., Kazeev N. et al., Journal of High Energy Physics 2019 Vol. 6 P. 1-27
The first untagged decay-time-integrated amplitude analysis of Bs0 → KS0K±π∓ decays is performed using a sample corresponding to 3.0 fb−1 of pp collision data recorded with the LHCb detector during 2011 and 2012. The data are described with an amplitude model that contains contributions from the intermediate resonances K*(892)0,+, K2*(1430)0,+ and K0*(1430)0,+, and their charge conjugates. Measurements of the branching fractions of the decay modes Bs0 → K*(892)±K∓ and 𝐵0𝑠→𝐾∗(---)(892)0𝐾0(---)Bs0→K∗(---)(892)0K0(---) are in ...
Added: March 16, 2020
Derkach D., Kazeev N., Ratnikov F. et al., Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 2020 Vol. 952 No. 0168-9002 P. 161804
We propose a way to simulate Cherenkov detector response using a generative adversarial neural network to bypass low-level details. This network is trained to reproduce high level features of the simulated detector events based on input observables of incident particles. This allows the dramatic increase of simulation speed. We demonstrate that this approach provides simulation ...
Added: February 11, 2019
Kiselyova N. N., Dudarev V., Ryazanov V. V. et al., Inorganic Materials: Applied Research 2021 Vol. 12 No. 2 P. 328-336
New chalcospinels of the most common compositions were predicted: AIBIIICIVX4 (X = S or Se)
and AIIBIIICIIIS4 (A, B, and C are various chemical elements). They are promising for the search for new
materials for magneto-optical memory elements, sensors, and anodes in sodium-ion batteries. The parameter
“a” values of their crystal lattice are estimated. When predicting, only the ...
Added: April 2, 2021
Springer, 2017
This valuable source for graduate students and researchers provides a comprehensive introduction to current theories and applications in optimization methods and network models. Contributions to this book are focused on new efficient algorithms and rigorous mathematical theories, which can be used to optimize and analyze mathematical graph structures with massive size and high density induced ...
Added: June 26, 2017