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Деркач Денис Александрович

Факультет компьютерных наук

Профиль на hse.ru ↗ тел.: 27266
Публикаций
226
Языков
3
Наград
6
Конференций
0
Профиль Публикации (226) Курсы (9)

Профессиональные интересы

физика высоких энергийанализ данных

Должности

  • Заведующий лабораторией — Факультет компьютерных наук, Институт искусственного интеллекта и цифровых наук, Научно-учебная лаборатория методов анализа больших данных
  • Доцент — Факультет компьютерных наук, Департамент больших данных и информационного поиска
  • Научный руководитель образовательной программы — Умные устройства: аппаратная разработка

Био

  • · Начал работать в НИУ ВШЭ в 2015 году.
  • · Научно-педагогический стаж: 7 лет.

Образование

  • 2010 · PhD: Университет Париж XI
  • 2007 · Магистратура: Санкт-Петербургский государственный университет, специальность «Физика», квалификация «Магистр»
  • 2004 · Бакалавриат: Санкт-Петербургский государственный университет, специальность «Физика», квалификация «Бакалавр»

Опыт работы

  • · 2017: н. в

Награды и поощрения

  • · Медаль "Признание - 10 лет успешной работы" НИУ ВШЭ (сентябрь 2025)
  • · Благодарность первого проректора НИУ ВШЭ (август 2024)
  • · Благодарность НИУ ВШЭ (май 2024)
  • · Почетная грамота Министерства науки и высшего образования Российской Федерации (ноябрь 2022)
  • · Благодарность первого проректора НИУ ВШЭ (август 2022)
  • · Благодарность Факультета компьютерных наук НИУ ВШЭ (август 2018)

Гранты и проекты

  • — · на соискание учёной степени кандидата наук

Идентификаторы исследователя

Публикации (226)

Updated search for 𝐵+𝑐 decays to two charm mesons

2021 · ARTICLE · en

A data set corresponding to an integrated luminosity of 9 fb−1 of proton-proton collisions collected by the LHCb experiment has been analysed to search for 𝐵+𝑐→𝐷(∗)+(𝑠)(---)𝐷(∗)0Bc+→D(s)(∗)+(---)D(∗)0 decays. The decays are fully or partially reconstructed, where one or two missing neutral pions or photons from the decay of an excited charm meson are allowed. Upper limits for the branching fractions, normalised to B+ decays to final states with similar topologies, are obtained for sixteen 𝐵+𝑐Bc+ decay modes. For the decay 𝐵+𝑐→𝐷+𝑠𝐷⎯⎯⎯⎯⎯0Bc+→Ds+D¯0, an excess with a significance of 3.4 standard deviations is found.

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Measurement of J/ψ production cross-sections in pp collisions at s√ = 5 TeV

2021 · ARTICLE · en

The production cross-sections of J/ψ mesons in proton-proton collisions at a centre-of-mass energy of 𝑠√s = 5 TeV are measured using a data sample corresponding to an integrated luminosity of 9.13 ± 0.18 pb−1, collected by the LHCb experiment. The cross-sections are measured differentially as a function of transverse momentum, pT, and rapidity, y, and separately for J/ψ mesons produced promptly and from beauty hadron decays (nonprompt). With the assumption of unpolarised J/ψ mesons, the production cross-sections integrated over the kinematic range 0 T 20 GeV/c and 2.0 4.5 are 𝜎prompt 𝐽/𝜓=8.154±0.010±0.283 μb,𝜎nonprompt 𝐽/𝜓=0.820±0.003±0.034 μb,σprompt J/ψ=8.154±0.010±0.283 μb,σnonprompt J/ψ=0.820±0.003±0.034 μb, where the first uncertainties are statistical and the second systematic. These cross-sections are compared with those at 𝑠√s = 8 TeV and 13 TeV, and are used to update the measurement of the nuclear modification factor in proton-lead collisions for J/ψ mesons at a centre-of-mass energy per nucleon pair of 𝑠NN‾‾‾‾√sNN = 5 TeV. The results are compared with theoretical predictions.

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Precise measurement of the fs/fd ratio of fragmentation fractions and of Bs0 decay branching fractions

2021 · ARTICLE · en

The ratio of the B0s and B0 fragmentation fractions, fs=fd, in proton-proton collisions at the LHC, is obtained as a function of B-meson transverse momentum and collision center-of-mass energy from the combined analysis of different B-decay channels measured by the LHCb experiment. The results are described by a linear function of the meson transverse momentum or with a function inspired by Tsallis statistics. Precise measurements of the branching fractions of the B0s → J=ψφ and B0s → D−s πþ decays are performed, reducing their uncertainty by about a factor of 2 with respect to previous world averages. Numerous B0s decay branching fractions, measured at the LHCb experiment, are also updated using the new values of fs=fd and branching fractions of normalization channels. These results reduce a major source of systematic uncertainty in several searches for new physics performed through measurements of B0s branching fractions.

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Search for the doubly heavy baryons Ω0bc and Ξ0bc decaying to Λ+cπ− and Ξ+cπ−

2021 · ARTICLE · en

The first search for the doubly heavy Ω0bc baryon and a search for Ξ0bc baryon are performed using pp collision data collected via the LHCb experiment from 2016 to 2018 at a centre-of-mass energy of 13TeV, corresponding to an integrated luminosity of 5.2fb−1. The baryons are reconstructed via their decays to Λ+cπ− and Ξ+cπ−. No significant excess is found for invariant masses between 6700 and 7300MeV/c2, in a rapidity range from 2.0 to 4.5 and a transverse momentum range from 2 to 20GeV/c. Upper limits are set on the ratio of the Ω0bc and Ξ0bc production cross-section times the branching fraction to Λ+cπ− (Ξ+cπ−) relative to that of the Λ0b (Ξ0b) baryon, for different lifetime hypotheses, at 95% confidence level. The upper limits range from 0.5×10−4 to 2.5×10−4 for the Ω0bc→Λ+cπ− (Ξ0bc→Λ+cπ−) decay, and from 1.4×10−3 to 6.9×10−3 for the Ω0bc→Ξ+cπ− (Ξ0bc→Ξ+cπ−) decay, depending on the considered mass and lifetime of the Ω0bc (Ξ0bc) baryon.

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Search for CP violation in Ξ−b→pK−K−decays

2021 · ARTICLE · en

A search for CP violation in charmless three-body Ξ−b→pK−K− decays is performed using pp collision data recorded with the LHCb detector, corresponding to integrated luminosities of 1 fb−1 at a center-of-mass energy √s=7 TeV, 2 fb−1 at √s=8 TeV and 2 fb−1 at √s=13 TeV. A good description of the phase-space distribution is obtained with an amplitude model containing contributions from Σ(1385), Λ(1405), Λ(1520), Λ(1670), Σ(1775) and Σ(1915) resonances. The model allows for CP -violation effects, which are found to be consistent with zero. The branching fractions of Ξ−b→Σ(1385)K−, Ξ−b→Λ(1405)K−, Ξ−b→Λ(1520)K−, Ξ−b→Λ(1670)K−, Ξ−b→Σ(1775)K− and Ξ−b→Σ(1915)K− decays are also reported. In addition, an upper limit is placed on the product of ratios of Ω−b and Ξ−b fragmentation fractions and the Ω−b→pK−K− and Ξ−b→pK−K− branching fractions.

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Cherenkov detectors fast simulation using neural networks

2020 · ARTICLE · en

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 precision which is consistent with the baseline and discuss possible implications of these results.

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Search for the doubly charmed baryon Ξ cc

2020 · ARTICLE · en

A search for the doubly charmed baryon Ξ cc is performed through its decay to the Λ + c K − π + final state, using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV. The data correspond to a total integrated luminosity of 9 fb −1 . No significant signal is observed in the mass range from 3.4 to 3.8 GeV/c 2 . Upper limits are set at 95% credibility level on the ratio of the Ξ cc production cross-section times the branching fraction to that of Λ + c and Ξ cc baryons. The limits are determined as functions of the Ξ cc mass for different lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 4 to 15 GeV/c.

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Measurement of 𝜓(2𝑆) production cross-sections in proton-proton collisions at √𝑠=7 and 13 TeV

2020 · ARTICLE · en

The cross-sections of 𝜓(2𝑆) meson production in proton-proton collisions at 𝑠√=13 TeV are measured with a data sample collected by the LHCb detector corresponding to an integrated luminosity of 275 pb−1. The production cross-sections for prompt 𝜓(2𝑆) mesons and those for 𝜓(2𝑆) mesons from b-hadron decays (𝜓(2𝑆)-from- 𝑏) are determined as functions of the transverse momentum, 𝑝T, and the rapidity, y, of the 𝜓(2𝑆) meson in the kinematic range 2𝑝T𝑐 and 2.0𝑦 . The production cross-sections integrated over this kinematic region are 𝜎( prompt 𝜓(2𝑆),13 TeV)=1.430±0.005 (stat)±0.099 (syst)μb,𝜎(𝜓(2𝑆)-from- 𝑏,13 TeV)=0.426±0.002 (stat)±0.030 (syst)μb. A new measurement of 𝜓(2𝑆) production cross-sections in pp collisions at 𝑠√=7 TeV is also performed using data collected in 2011, corresponding to an integrated luminosity of 614 pb−1. The integrated production cross-sections in the kinematic range 3.5𝑝T𝑐 and 2.0𝑦 are 𝜎( prompt 𝜓(2𝑆),7 TeV)=0.471±0.001 (stat)±0.025 (syst)μb,𝜎(𝜓(2𝑆)-from- 𝑏,7 TeV)=0.126±0.001 (stat)±0.008 (syst)μb. All results show reasonable agreement with theoretical calculations.

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(1 + ε)-class Classification: an Anomaly Detection Method for Highly Imbalanced or Incomplete Data Sets

2020 · ARTICLE · en

Anomaly detection is not an easy problem since distribution of anomalous samples is unknown a priori. We explore a novel method that gives a trade-off possibility between one-class and two-class approaches, and leads to a better performance on anomaly detection problems with small or non-representative anomalous samples. The method is evaluated using several data sets and compared to a set of conventional one-class and two-class approaches.

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Fast Data-Driven Simulation of Cherenkov Detectors Using Generative Adversarial Networks

2020 · ARTICLE · en

The increasing luminosities of future Large Hadron Collider runs and next generation of collider experiments will require an unprecedented amount of simulated events to be produced. Such large scale productions are extremely demanding in terms of computing resources. Thus new approaches to event generation and simulation of detector responses are needed. In LHCb, the accurate simulation of Cherenkov detectors takes a sizeable fraction of CPU time. An alternative approach is described here, when one generates high-level reconstructed observables using a generative neural network to bypass low level details. This network is trained to reproduce the particle species likelihood function values based on the track kinematic parameters and detector occupancy. The fast simulation is trained using real data samples collected by LHCb during run 2. We demonstrate that this approach provides high-fidelity results.

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Курсы (9)