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Болдырев Алексей Сергеевич

Факультет компьютерных наук

Профиль на hse.ru ↗ тел.: 27266
Публикаций
26
Языков
3
Наград
5
Конференций
3
Профиль Публикации (274) Курсы (12)

Профессиональные интересы

Физика высоких энергийМашинное обучение и анализ данных

Должности

  • Научный сотрудник — 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
  • Приглашенный преподаватель — НИУ ВШЭ в Нижнем Новгороде, Факультет менеджмента, Департамент маркетинга и предпринимательства

Био

  • · Начал работать в НИУ ВШЭ в 2018 году.
  • · Научно-педагогический стаж: 13 лет.

Образование

  • 2013 · Кандидат физико-математических наук
  • 2010 · Специалитет: Московский государственный университет им. М.В. Ломоносова, специальность «Физика атомного ядра и частиц», квалификация «Физик»

Опыт работы

  • · 2020: Научный сотрудник Научно-учебной лаборатории методов анализа больших данных НИУ ВШЭ ( настоящее время)
  • · 2020: Доцент Департамента больших данных и информационного поиска ( настоящее время) Постдок НИУ ВШЭ (2018–2020) Старший научный сотрудник Института ядерной физики им. Д.В. Скобельцына, МГУ им. М.В. Ломоносова (2017–2018)
  • · Младший научный сотрудник Физического института им. П.Н. Лебедева РАН (2006-2017) Научный сотрудник Института ядерной физики им. Д.В. Скобельцына МГУ им. М.В. Ломоносова (2016) Стипендия TRIL, Международный центр теоретической физики Абдуса Салама (ICTP) (2015–2016) Научный сотрудник Института ядерной физики им. Д.В. Скобельцына МГУ им. М.В. Ломоносова (2014–2015)

Награды и поощрения

  • · Благодарность НИУ ВШЭ (май 2024)
  • · Благодарственное письмо проректора НИУ ВШЭ (сентябрь 2022)
  • · Надбавка за публикацию в журнале из Списка А (и приравненном к нему научном издании) (2023–2024)
  • · Надбавка за публикацию в международном рецензируемом научном издании (2022–2023, 2021–2022, 2020–2022)
  • · Надбавка за регулярные публикации в международных рецензируемых научных изданиях (2024–2029)

Гранты и проекты

  • — · Факультет компьютерных наук НИУ ВШЭ, Сколтех и Физический институт им. П. Н. Лебедева РАН провели Московскую международную школу физики 2024

Конференции (3)

Показать все
  • · 2022: Second MODE Workshop on Differentiable Programming for Experiment Design (Колумбари, Крит). Доклад: LHCb ECAL optimization
  • · 2021: First MODE Workshop on Differentiable Programming (Лувэн-ла-Нёв). Доклад: Optimization of LHCb calorimeter
  • · 2020: Instrumentation for Colliding Beam Physics (Новосибирск). Доклад: ML-assisted versatile approach to Calorimeter R&D

Идентификаторы исследователя

Публикации (274)

Study of B+c→χcπ+ decays

2024 · ARTICLE · en

A study of Bc+→χcπ+ decays is reported using proton-proton collision data, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb−1. The decay Bc+→χc2π+ is observed for the first time, with a significance exceeding seven standard deviations. The relative branching fraction with respect to the Bc+→J/ψπ+ decay is measured to be BBc+→χc2π+BBc+→J/ψπ+=0.37±0.06±0.02±0.01, where the first uncertainty is statistical, the second is systematic, and the third is due to the knowledge of the χc2 → J/ψγ branching fraction. No significant Bc+→χc1π+ signal is observed and an upper limit for the relative branching fraction for the Bc+→χc1π+ and Bc+→χc2π+ decays of BBc+→χc1π+BBc+→χc2π+= is set at the 90% confidence level.

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Search for $B_c^+ \to \pi^+\mu^+\mu^-$ decays and measurement of the branching fraction ratio ${\cal B}(B_c^+ \to \psi(2S)\pi^+)/{\cal B}(B_c^+ \to J/\psi\pi^+)$

2024 · ARTICLE · en

The first search for nonresonant Bc+→π+μ+μ− decays is reported. The analysis uses proton–proton collision data collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9fb−1. No evidence for an excess of signal events over background is observed and an upper limit is set on the branching fraction ratio B(Bc+→π+μ+μ−)/B(Bc+→J/ψπ+)

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Amplitude analysis of the $B^0 \to K^{*0}\mu^+\mu^-$ decay

2024 · ARTICLE · en

An amplitude analysis of the 𝐵0→𝐾*0⁢𝜇+⁢𝜇− decay is presented using a dataset corresponding to an integrated luminosity of 4.7 fb−1 of 𝑝⁢𝑝 collision data collected with the LHCb experiment. For the first time, the coefficients associated to short-distance physics effects, sensitive to processes beyond the standard model, are extracted directly from the data through a 𝑞2-unbinned amplitude analysis, where 𝑞2 is the 𝜇+⁢𝜇− invariant mass squared. Long-distance contributions, which originate from nonfactorizable QCD processes, are systematically investigated, and the most accurate assessment to date of their impact on the physical observables is obtained. The pattern of measured corrections to the short-distance couplings is found to be consistent with previous analyses of 𝑏- to 𝑠-quark transitions, with the largest discrepancy from the standard model predictions found to be at the level of 1.8 standard deviations. The global significance of the observed differences in the decay is 1.4 standard deviations.

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Determination of short- and long-distance contributions in $B^0 \to K^{*0}\mu^+\mu^-$ decays

2024 · ARTICLE · en

An amplitude analysis of the 𝐵0→𝐾*0⁢𝜇+⁢𝜇− decay is presented. The analysis is based on data collected by the LHCb experiment from proton-proton collisions at √𝑠=7, 8 and 13 TeV, corresponding to an integrated luminosity of 4.7 fb−1. For the first time, Wilson coefficients and nonlocal hadronic contributions are accessed directly from the unbinned data, where the latter are parametrized as a function of 𝑞2 with a polynomial expansion. Wilson coefficients and nonlocal hadronic parameters are determined under two alternative hypotheses: the first relies on experimental information alone, while the second one includes information from theoretical predictions for the nonlocal contributions. Both models obtain similar results for the parameters of interest. The overall level of compatibility with the Standard Model is evaluated to be between 1.8 and 1.9 standard deviations when looking at the 𝒞9 Wilson coefficient alone, and between 1.3 and 1.4 standard deviations when considering the full set of 𝒞9,𝒞10,𝒞′9 and 𝒞′10 Wilson coefficients. The ranges reflect the theoretical assumptions made in the analysis.

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Momentum scale calibration of the LHCb spectrometer

2024 · ARTICLE · en

For accurate determination of particle masses accurate knowledge of the momentum scale of the detectors is crucial. The procedure used to calibrate the momentum scale of the LHCb spectrometer is described and illustrated using the performance obtained with an integrated luminosity of 1.6 fb-1collected during 2016 in pp running. The procedure uses large samples of J/ψ → μ+μ- and B+ → J/ψK+ decays and leads to a relative accuracy of 3 × 10-4 on the momentum scale.

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Measurement of associated J/ψ-ψ(2S) production cross-section in pp collisions at √s = 13 TeV

2024 · ARTICLE · en

The cross-section of associated J/ψ-ψ(2S) production in proton-proton collisions at a centre-of-mass energy of s = 13 TeV is measured using a data sample corresponding to an integrated luminosity of 4.2 fb−1, collected by the LHCb experiment. The measurement is performed for both J/ψ and ψ(2S) mesons having transverse momentum pT 14 GeV/c and rapidity 2.0 4.5, assuming negligible polarisation of the J/ψ and ψ(2S) mesons. The production cross-section is measured to be 4.5 ± 0.7 ± 0.3 nb, where the first uncertainty is statistical and the second systematic. The differential cross-sections are measured as functions of several kinematic variables of the J/ψ-ψ(2S) candidates. The results are combined with a measurement of J/ψ-J/ψ production, giving a cross-section ratio between J/ψ-ψ(2S) and J/ψ-J/ψ production of 0.274 ± 0.044 ± 0.008, where the first uncertainty is statistical and the second systematic.

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Observation of $\Lambda_b^0 \to \Lambda_c^+ \bar{D}^{(*)0} K^-$ and $\Lambda_b^0 \to \Lambda_c^+ D_s^{*-}$ decays

2024 · ARTICLE · en

The decays Λb0→Λc+D¯(∗)0K− and Λb0→Λc+Ds∗− are observed for the first time, in proton-proton collision data at s=13TeV, corresponding to an integrated luminosity of 5.4fb−1 collected with the LHCb detector. Their ratios of branching fractions with respect to the Λb0→Λc+Ds− mode are measured to be B(Λb0→Λc+D¯0K−)B(Λb0→Λc+Ds−)=0.1908−0.0034+0.0036−0.0018+0.0016±0.0038,B(Λb0→Λc+D¯∗0K−)B(Λb0→Λc+Ds−)=0.589−0.017+0.018−0.018+0.017±0.012,B(Λb0→Λc+Ds∗−)B(Λb0→Λc+Ds−)=1.668±0.022−0.055+0.061, where the first uncertainties are statistical, the second systematic, and the third, for the Λb0→Λc+D¯(∗)0K− decays, are due to the uncertainties on the branching fractions of the Ds−→K−K+π− and D¯0→K+π− decay modes. The measured branching fractions probe factorization assumptions in effective theories and provide the normalization for future pentaquark searches in Λb0→Λc+D¯(∗)0K− decay channels.

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Measurement of $J/\psi$-pair production in $pp$ collisions at $\sqrt{s} = 13$ TeV and study of gluon transverse momentum-dependent PDFs

2024 · ARTICLE · en

The production cross-section of J/ψ pairs in proton-proton collisions at a centre-of-mass energy of s = 13 TeV is measured using a data sample corresponding to an integrated luminosity of 4.2 fb−1 collected by the LHCb experiment. The measurement is performed with both J/ψ mesons in the transverse momentum range 0 T 14 GeV/c and rapidity range 2.0 4.5. The cross-section of this process is measured to be 16.36 ± 0.28 (stat) ± 0.88 (syst) nb. The contributions from single-parton scattering and double-parton scattering are separated based on the dependence of the cross-section on the absolute rapidity difference ∆y between the two J/ψ mesons. The effective cross-section of double-parton scattering is measured to be σeff = 13.1 ± 1.8 (stat) ± 2.3 (syst) mb. The distribution of the azimuthal angle ϕCS of one of the J/ψ mesons in the Collins-Soper frame and the pT-spectrum of the J/ψ pairs are also measured for the study of the gluon transverse-momentum dependent distributions inside protons. The extracted values of ⟨cos 2ϕCS⟩ and ⟨cos 4ϕCS⟩ are consistent with zero, but the presence of azimuthal asymmetry at a few percent level is allowed.

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A model-independent measurement of the CKM angle γ in partially reconstructed B± → D*h± decays with D → K0Sh+h− (h = π, K)

2024 · ARTICLE · en

A measurement of CP-violating observables in B± → D*K± and B± → D*π± decays is made where the photon or neutral pion from the D* → Dγ or D* → Dπ0 decay is not reconstructed. The D meson is reconstructed in the self-conjugate decay modes, D → KS0π+π− or D → KS0K+K−. The distribution of signal yields in the D decay phase space is analysed in a model-independent way. The measurement uses a data sample collected in proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of approximately 9 fb−1. The B± → D*K± and B± → D*π± CP-violating observables are interpreted in terms of hadronic parameters and the CKM angle γ, resulting in a measurement of γ = (92−17+21)°. The total uncertainty includes the statistical and systematic uncertainties, and the uncertainty due to external strong-phase inputs.

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Measurement of forward charged hadron flow harmonics in peripheral PbPb collisions at √𝑠𝑁⁢𝑁=5.02TeV with the LHCb detector

2024 · ARTICLE · en

Flow harmonic coefficients, 𝑣𝑛, which are the key to studying the hydrodynamics of the quark-gluon plasma (QGP) created in heavy-ion collisions, have been measured in various collision systems and kinematic regions and using various particle species. The study of flow harmonics in a wide pseudorapidity range is particularly valuable to understand the temperature dependence of the shear viscosity to entropy density ratio of the QGP. This paper presents the first LHCb results of the second- and the third-order flow harmonic coefficients of charged hadrons as a function of transverse momentum in the forward region, corresponding to pseudorapidities between 2.0 and 4.9, using the data collected from PbPb collisions in 2018 at a center-of-mass energy of 5.02 TeV. The coefficients measured using the two-particle angular correlation analysis method are smaller than the central-pseudorapidity measurements at ALICE and ATLAS from the same collision system but share similar features.

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Курсы (12)