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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)

Measurement of the branching fraction of the B0→D+sπ− decay

2021 · ARTICLE · en

A branching fraction measurement of the 𝐵0→𝐷+𝑠𝜋−B0→Ds+π− decay is presented using proton–proton collision data collected with the LHCb experiment, corresponding to an integrated luminosity of 5.0fb−15.0fb−1. The branching fraction is found to be (𝐵0→𝐷+𝑠𝜋−)=(19.4±B(B0→Ds+π−)=(19.4± 1.8±1.3±1.2)×10−61.8±1.3±1.2)×10−6, where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the 𝐵0→𝐷−𝜋+B0→D−π+, 𝐷+𝑠→𝐾+𝐾−𝜋+Ds+→K+K−π+ and 𝐷−→𝐾+𝜋−𝜋−D−→K+π−π−branching fractions. This is the most precise single measurement of this quantity to date. As this decay proceeds through a single amplitude involving a 𝑏→𝑢b→u charged-current transition, the result provides information on non-factorisable strong interaction effects and the magnitude of the Cabibbo–Kobayashi–Maskawa matrix element 𝑉𝑢𝑏Vub. Additionally, the collision energy dependence of the hadronisation-fraction ratio 𝑓𝑠/𝑓𝑑fs/fd is measured through 𝐵⎯⎯⎯⎯0𝑠→𝐷+𝑠𝜋−B¯s0→Ds+π− and 𝐵0→𝐷−𝜋+B0→D−π+ decays.

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Observation of Multiplicity Dependent Prompt χc1(3872) and ψ(2S) Production in pp Collisions

2021 · ARTICLE · en

The production of χc1(3872) and ψ(2S) hadrons is studied as a function of charged particle multiplicity in pp collisions at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 2 fb−1. For both states, the fraction that is produced promptly at the collision vertex is found to decrease as charged particle multiplicity increases. The ratio of χc1(3872) to ψ(2S) cross sections for promptly produced particles is also found to decrease with multiplicity, while no significant dependence on multiplicity is observed for the equivalent ratio of particles produced away from the collision vertex in b-hadron decays. This behavior is consistent with a calculation that models the χc1(3872) structure as a compact tetraquark. Comparisons with model calculations and implications for the binding energy of the χc1(3872) state are discussed.

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Measurement of the CKM angle γ in B± → DK± and B± → Dπ± decays with D → 𝐾0Sh+h−

2021 · ARTICLE · en

A measurement of CP-violating observables is performed using the decays B± → DK± and B± → Dπ±, where the D meson is reconstructed in one of the self-conjugate three-body final states 𝐾0SKS0π+π− and 𝐾0SKS0K+K− (commonly denoted 𝐾0SKS0h+h−). The decays are analysed in bins of the D-decay phase space, leading to a measurement that is independent of the modelling of the D-decay amplitude. The observables are inter- preted in terms of the CKM angle γ. Using a data sample corresponding to an integrated luminosity of 9 fb−1 collected in proton-proton collisions at centre-of mass energies of 7, 8, and 13 TeV with the LHCb experiment, γ is measured to be (68.7+5.2−5.1)∘(68.7−5.1+5.2)∘. The hadronic parameters 𝑟𝐷𝐾𝐵,𝑟𝐷𝜋𝐵,𝛿𝐷𝐾𝐵,and𝛿𝐷𝜋𝐵rBDK,rBDπ,δBDK,andδBDπ, which are the ratios and strong-phase differences of the suppressed and favoured B± decays, are also reported.

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Measurement of differential 𝑏𝑏⎯⎯⎯- and 𝑐𝑐⎯⎯⎯-dijet cross-sections in the forward region of pp collisions at 𝑠√ = 13 TeV

2021 · ARTICLE · en

The inclusive 𝑏𝑏⎯⎯⎯bb¯- and 𝑐𝑐⎯⎯⎯cc¯-dijet production cross-sections in the forward region of pp collisions are measured using a data sample collected with the LHCb detector at a centre-of-mass energy of 13 TeV in 2016. The data sample corresponds to an integrated luminosity of 1.6 fb−1. Differential cross-sections are measured as a function of the transverse momentum and of the pseudorapidity of the leading jet, of the rapidity difference between the jets, and of the dijet invariant mass. A fiducial region for the measurement is defined by requiring that the two jets originating from the two b or c quarks are emitted with transverse momentum greater than 20 GeV/c, pseudorapidity in the range 2.2 4.2, and with a difference in the azimuthal angle between the two jets greater than 1.5. The integrated 𝑏𝑏⎯⎯⎯bb¯-dijet cross-section is measured to be 53.0 ± 9.7 nb, and the total 𝑐𝑐⎯⎯⎯cc¯-dijet cross-section is measured to be 73 ± 16 nb. The ratio between 𝑐𝑐⎯⎯⎯cc¯- and 𝑏𝑏⎯⎯⎯bb¯-dijet cross-sections is also measured and found to be 1.37 ± 0.27. The results are in agreement with theoretical predictions at next-to-leading order.

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Observation of the suppressed Lambda 0 b rightarrow DpK - decay with D rightarrow K + pi - and measurement of its CP asymmetry

2021 · ARTICLE · en

A study of baryon decays to the Dp\Km final state is presented based on a proton-proton collision data sample corresponding to an integrated luminosity of 9\invfb collected with the LHCb detector. Two decays are considered, \Lb→D\proton\Km with D→\Km\pip and D→\Kp\pim, where D represents a superposition of and states. The latter process is expected to be suppressed relative to the former, and is observed for the first time. The ratio of branching fractions of the two decays is measured, and the asymmetry of the suppressed mode, which is sensitive to the CKM angle γ, is also reported.

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Machine Learning in Calorimeter optimization

2021 · ARTICLE · en

The optimization of big industrial setups and the accompanying detailed simulations of internal physical processes require complex and time-consuming simulation calculations. We propose a versatile approach that can alleviate difficulties in solving this problem and show this using an example of electromagnetic calorimeter optimization at a Large Hadron Collider experiment. Our approach consists of a block representation of the calorimeter optimization process from setting sensitive characteristics of modules and their locations to obtaining a quality metric and applying machine learning methods. The main blocks are signal and background particles generation and their propagation to the calorimeter, the generation of electromagnetic showers of signal and noise in modules with a given technology, the combination of signal and noise with the simulation of different luminosities, the energy and spatial reconstruction of the signal and obtaining the final metric. This approach allows us to evaluate the operational characteristics of the calorimeter and find a more suitable configuration with the necessary quality without extensive use of time-consuming resources.

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NFAD: fixing anomaly detection using normalizing flows

2021 · ARTICLE · en

Anomaly detection is a challenging task that frequently arises in practically all areas of industry and science, from fraud detection and data quality monitoring to finding rare cases of diseases and searching for new physics. Most of the conventional approaches to anomaly detection, such as one-class SVM and Robust Auto-Encoder, are one-class classification methods, i.e., focus on separating normal data from the rest of the space. Such methods are based on the assumption of separability of normal and anomalous classes, and subsequently do not take into account any available samples of anomalies. Nonetheless, in practical settings, some anomalous samples are often available; however, usually in amounts far lower than required for a balanced classification task, and the separability assumption might not always hold. This leads to an important task—incorporating known anomalous samples into training procedures of anomaly detection models. In this work, we propose a novel model-agnostic training procedure to address this task. We reformulate one-class classification as a binary classification problem with normal data being distinguished from pseudo-anomalous samples. The pseudo-anomalous samples are drawn from low-density regions of a normalizing flow model by feeding tails of the latent distribution into the model. Such an approach allows to easily include known anomalies into the training process of an arbitrary classifier. We demonstrate that our approach shows comparable performance on one-class problems, and, most importantly, achieves comparable or superior results on tasks with variable amounts of known anomalies.

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First measurement of the CP-violating phase in Bs0 → J / ψ ( → e + e - ) ϕ decays

2021 · ARTICLE · en

A flavour-tagged time-dependent angular analysis of {{B} ^0_{s}} \!\rightarrow {{J /\psi }} \phi decays is presented where the {J /\psi } meson is reconstructed through its decay to an e ^+e ^- pair. The analysis uses a sample of pp collision data recorded with the LHCb experiment at centre-of-mass energies of 7 and 8\text {\,Te V} , corresponding to an integrated luminosity of 3 \text {\,fb} ^{-1} . The C\!P-violating phase and lifetime parameters of the {B} ^0_{s} system are measured to be {\phi _{{s}}} =0.00\pm 0.28\pm 0.07\text {\,rad}, {\Delta \Gamma _{{s}}} =0.115\pm 0.045\pm 0.011\text {\,ps} ^{-1} and {\Gamma _{{s}}} =0.608\pm 0.018\pm 0.012\text {\,ps} ^{-1} where the first uncertainty is statistical and the second systematic. This is the first time that C\!P-violating parameters are measured in the {{B} ^0_{s}} \!\rightarrow {{J /\psi }} \phi decay with an e ^+e ^- pair in the final state. The results are consistent with previous measurements in other channels and with the Standard Model predictions.

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Simultaneous determination of CKM angle γ and charm mixing parameters

2021 · ARTICLE · en

A combination of measurements sensitive to the CP violation angle γ of the Cabibbo-Kobayashi-Maskawa unitarity triangle and to the charm mixing parameters that describe oscillations between D0 and 𝐷⎯⎯⎯⎯⎯D¯0 mesons is performed. Results from the charm and beauty sectors, based on data collected with the LHCb detector at CERN’s Large Hadron Collider, are combined for the first time. This method provides an improvement on the precision of the charm mixing parameter y by a factor of two with respect to the current world average. The charm mixing parameters are determined to be 𝑥=(0.400+0.052−0.053)%x=(0.400−0.053+0.052)% and y = (0.630+0.033−0.030)%(0.630−0.030+0.033)%. The angle γ is found to be γ = (65.4+3.8−4.2)∘(65.4−4.2+3.8)∘ and is the most precise determination from a single experiment.

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Search for the doubly charmed baryon 𝛯+𝑐𝑐 in the 𝛯+𝑐𝜋−𝜋+ final state

2021 · ARTICLE · en

A search for the doubly charmed baryon 𝛯+𝑐𝑐Ξcc+ is performed in the 𝛯+𝑐𝜋−𝜋+Ξc+π−π+ invariant-mass spectrum, where the 𝛯+𝑐Ξc+ baryon is reconstructed in the pK−π+ final state. The study uses proton-proton collision data collected with the LHCb detector at a centre- of-mass energy of 13 TeV, corresponding to a total integrated luminosity of 5.4 fb−1. No significant signal is observed in the invariant-mass range of 3.4–3.8 GeV/c2. Upper limits are set on the ratio of branching fractions multiplied by the production cross-section with respect to the 𝛯++𝑐𝑐Ξcc++ → (𝛯+𝑐Ξc+ → pK−π+)π+ decay for different 𝛯+𝑐𝑐Ξcc+ mass and lifetime hypotheses in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 2.5 to 25 GeV/c. The results from this search are combined with a previously published search for the 𝛯+𝑐𝑐Ξcc+ → 𝛬+𝑐Λc+K−π+ decay mode, yielding a maximum local significance of 4.0 standard deviations around the mass of 3620 MeV/c2, including systematic uncertainties. Taking into account the look-elsewhere effect in the 3.5–3.7 GeV/c2 mass window, the combined global significance is 2.9 standard deviations including systematic uncertainties.

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Курсы (9)