DSA Faculty
API
← к списку преподавателей

Пахлов Павел Николаевич

Московский институт электроники и математики им. А.Н. Тихонова

Профиль на hse.ru ↗ тел.: 00000
Публикаций
126
Языков
2
Наград
3
Конференций
2
Профиль Публикации (126) Курсы (2)

Профессиональные интересы

физика элементарных частиц

Должности

  • Ведущий научный сотрудник — Московский институт электроники и математики им. А.Н. Тихонова, Международная лаборатория физики элементарных частиц
  • Профессор — Московский институт электроники и математики им. А.Н. Тихонова, Департамент электронной инженерии

Био

  • · Начал работать в НИУ ВШЭ в 2020 году.
  • · Научно-педагогический стаж: 8 лет.

Образование

  • 2008 · Доктор физико-математических наук: Высшая аттестационная комиссия Республика Болгария
  • 1990 · Специалитет: Московский физико-технический институт, специальность «Прикладная математика и физика», квалификация «Инженер-физик»

Опыт работы

  • · 2000 - н.в.: профессор кафедры физики элемнтарных частиц МФТИ
  • · 2009 - н.в.: профессор кафедры экспериментальной ядерной физики и космофизики МИФИ
  • · 2020 - н.в.: профессор кафедры дискретной математики МИЭМ ВШЭ

Награды и поощрения

  • · Надбавка за публикацию в журнале из Списка А (и приравненном к нему научном издании) (2025–2026, 2024–2025, 2023–2024)
  • · Надбавка за публикацию в международном рецензируемом научном издании (2021–2022)
  • · Лучший преподаватель — 2021–2022

Гранты и проекты

  • — · на соискание учёной степени кандидата наук

Конференции (2)

Показать все
  • · 2024: The 2024 International Workshop on Future Tau Charm Facilities (Хефей). Доклад: On possibility to measure all Michel parameters at SCTF
  • · 2020: 5th International Conference on Particle Physics and Astrophysics (Москва). Доклад: Recent experimental results in B physics

Идентификаторы исследователя

Публикации (126)

Evidence for 𝐵+→𝐾+⁢𝜈⁢𝜈 decays

2024 в печати · ARTICLE · en

We search for the rare decay 𝐵+ →𝐾+⁢𝜈⁢¯𝜈 in a 362 fb−1 sample of electron-positron collisions at the ϒ⁡(4⁢𝑆) resonance collected with the Belle II detector at the SuperKEKB collider. We use the inclusive properties of the accompanying 𝐵 meson in ϒ⁡(4⁢𝑆)→𝐵⁢¯𝐵 events to suppress background from other decays of the signal 𝐵 candidate and light-quark pair production. We validate the measurement with an auxiliary analysis based on a conventional hadronic reconstruction of the accompanying 𝐵meson. For background suppression, we exploit distinct signal features using machine learning methods tuned with simulated data. The signal-reconstruction efficiency and background suppression are validated through various control channels. The branching fraction is extracted in a maximum likelihood fit. Our inclusive and hadronic analyses yield consistent results for the 𝐵+→𝐾+⁢𝜈⁢¯𝜈 branching fraction of [2.7±0.5⁢(stat)±0.5⁢(syst)] ×10−5 and [1.1+0.9−0.8⁢(stat)+0.8−0.5⁢(syst)] ×10−5, respectively. Combining the results, we determine the branching fraction of the decay 𝐵+ →𝐾+⁢𝜈⁢¯𝜈to be [2.3±0.5⁢(stat)+0.5−0.4⁢(syst)] ×10−5, providing the first evidence for this decay at 3.5 standard deviations. The combined result is 2.7 standard deviations above the standard model expectation.

DOI ↗

Search for the 𝑒+⁢𝑒−→𝜂𝑏⁡(1⁢𝑆)⁢𝜔 and 𝑒+⁢𝑒−→𝜒𝑏⁢0⁡(1⁢𝑃)⁢𝜔 processes at √𝑠=10.745 GeV

2024 в печати · ARTICLE · en

We search for the 𝑒+⁢𝑒− →𝜂𝑏⁡(1⁢𝑆)⁢𝜔 and 𝑒+⁢𝑒− →𝜒𝑏⁢0⁡(1⁢𝑃)⁢𝜔 processes at a center-of-mass energy of 10.745 GeV, which is close to the peak of the ϒ⁡(10753) state. We use data collected by the Belle II experiment during a special run, corresponding to an integrated luminosity of 9.8 fb−1. We reconstruct 𝜔 →𝜋+⁢𝜋−⁢𝜋0 decays and use the 𝜔 meson’s recoil mass to search for the signals. We do not find evidence for either process, and set upper limits on the corresponding Born-level cross sections of 2.5 pb and 7.8 pb, respectively, at the 90% confidence level. The 𝜒𝑏⁢0⁡(1⁢𝑃)⁢𝜔 limit is the result of a combination of this analysis and a previous search using full reconstruction.

DOI ↗

Measurement of 𝐶⁢𝑃 asymmetries in 𝐵0→𝐾0𝑆⁢𝐾0𝑆⁢𝐾0𝑆 decays at Belle II

2024 в печати · ARTICLE · en

We report a measurement of decay-time-dependent charge-parity (𝐶⁢𝑃) asymmetries in 𝐵0→𝐾0𝑆⁢𝐾0𝑆⁢𝐾0𝑆 decays. We use 387×106 𝐵⁢¯𝐵 pairs collected at the ϒ⁡(4⁢𝑆) resonance with the Belle II detector at the SuperKEKB asymmetric-energy electron-positron collider. We reconstruct 220 signal events and extract the 𝐶⁢𝑃-violating parameters 𝑆 and 𝐶 from a fit to the distribution of the decay-time difference between the two 𝐵 mesons. The resulting confidence region is consistent with previous measurements in 𝐵0→𝐾0𝑆⁢𝐾0𝑆⁢𝐾0𝑆 and 𝐵0 →(𝑐⁢¯𝑐)⁢𝐾0 decays and with predictions based on the standard model.

DOI ↗

Test of light-lepton universality in τ decays with the Belle II experiment

2024 в печати · ARTICLE · en

We present a measurement of the ratio of branching fractions of the τlepton decaying to muons or electrons using data collected with the Belle II detector at the SuperKEKB e+e− collider. The sample has an integrated luminosity of 362 ± 2 fb−1 at a centre-of-mass energy of 10.58 GeV. Using an optimised event selection, a binned maximum likelihood fit is performed using the momentum spectra of the electron and muon candidates. The result, Rμ = 0.9675 ± 0.0007 ± 0.0036, where the first uncertainty is statistical and the second is systematic, is the most precise to date. It provides a stringent test of the light-lepton universality, translating to a ratio of the couplings of the muon and electron to the W boson in τ decays of 0.9974 ± 0.0019, in agreement with the standard model expectation of unity.

DOI ↗

New graph-neural-network flavor tagger for Belle II and measurement of sin 2⁢𝜙1 in 𝐵0→𝐽/𝜓⁢𝐾0S decays

2024 в печати · ARTICLE · en

We present GFlaT, a new algorithm that uses a graph-neural-network to determine the flavor of neutral 𝐵 mesons produced in ϒ⁡(4⁢𝑆) decays. It improves previous algorithms by using the information from all charged final-state particles and the relations between them. We evaluate its performance using 𝐵 decays to flavor-specific hadronic final states reconstructed in a 362 fb−1sample of electron-positron collisions collected at the ϒ⁡(4⁢𝑆) resonance with the Belle II detector at the SuperKEKB collider. We achieve an effective tagging efficiency of (37.40 ±0.43 ±0.36%), where the first uncertainty is statistical and the second systematic, which is 18% better than the previous Belle II algorithm. Demonstrating the algorithm, we use 𝐵0 →𝐽/𝜓⁢𝐾0S decays to measure the mixing-induced and direct 𝐶⁢𝑃 violation parameters, 𝑆 =(0.724 ±0.035 ±0.009) and 𝐶 =(−0.035 ±0.026±0.029).

DOI ↗

Search for lepton-flavor-violating τ− → μ−μ+μ− decays at Belle II

2024 в печати · ARTICLE · en

We present the result of a search for the charged-lepton-flavor violating decay τ− → μ−μ+μ− using a 424 fb−1 sample of data recorded by the Belle II experiment at the SuperKEKB e+e− collider. The selection of e+e− → τ+τ− events is based on an inclusive reconstruction of the non-signal tau decay, and on a boosted decision tree to suppress background. We observe one signal candidate, which is compatible with the expectation from background processes. We set a 90% confidence level upper limit of 1.9 × 10−8 on the branching fraction of the τ− → μ−μ+μ− decay, which is the most stringent bound to date.

DOI ↗

Measurement of the Michel parameters in leptonic τ-decays at Super Tau-Charm facility

2024 · ARTICLE · en

We present a new method for direct measurement of all Michel parameters in the 𝜏− → 𝜇− 𝜈_𝜇⁢ 𝜈_𝜏 decay related to the polarization of the daughter muon: 𝜉′, 𝜉′′, 𝜂′′, 𝛼′/𝐴, and 𝛽′/𝐴. The method is based on the reconstruction of the muon decays-in-flight in the tracker of the 𝑒+⁢𝑒− collider experiments and relies on the correlation between muon spin and its daughter electron momentum. The low probability of decay-in-flight in the tracker volume is compensated by the unprecedented statistics of modern flavor factories, which ultimately leads to the possibility of achieving high accuracy. We discuss the application of the suggested method in the experiments at 𝑒+⁢𝑒− colliders and present a feasibility study for the future Super Charm-Tau Factory experiment. We also discuss the result of the first use of the proposed method in the Belle experiment, confirming its applicability.

DOI ↗

A test of lepton flavor universality with a measurement of R(D*) using hadronic tagging at the Belle II experiment

2024 в печати · ARTICLE · en

The ratio of branching fractions 𝑅⁡(𝐷*) =ℬ⁡(¯𝐵 →𝐷*⁢𝜏−⁢¯𝜈𝜏)/ℬ⁡(¯𝐵 →𝐷*⁢ℓ−⁢¯𝜈ℓ), where ℓ is an electron or muon, is measured using a Belle II data sample with an integrated luminosity of 189 fb−1 at the SuperKEKB asymmetric-energy 𝑒+⁢𝑒− collider. Data is collected at the ϒ⁡(4⁢S) resonance, and one 𝐵meson in the ϒ⁡(4⁢S) →𝐵⁢¯𝐵 decay is fully reconstructed in hadronic decay modes. The accompanying signal 𝐵 meson is reconstructed as ¯𝐵 →𝐷*⁢𝜏−⁢¯𝜈𝜏 using leptonic 𝜏 decays. The normalization decay, ¯𝐵→𝐷*⁢ℓ−⁢¯𝜈ℓ, produces the same observable final-state particles. The ratio of branching fractions is extracted in a simultaneous fit to two signal-discriminating variables in both channels and yields 𝑅⁡(𝐷*) =0.262+0.041−0.039⁢(stat)+0.035−0.032⁢(syst). This result is consistent with the current world average and with Standard Model predictions.

DOI ↗

STCF conceptual design report (Volume 1): Physics & detector

2024 в печати · ARTICLE · en

The super τ-charm facility (STCF) is an electron–positron collider proposed by the Chinese particle physics community. It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5 × 1035 cm−2·s−1 or higher. The STCF will produce a data sample about a factor of 100 larger than that of the present τ-charm factory — the BEPCII, providing a unique platform for exploring the asymmetry of matter-antimatter (charge-parity violation), in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions, as well as searching for exotic hadrons and physics beyond the Standard Model. The STCF project in China is under development with an extensive R&D program. This document presents the physics opportunities at the STCF, describes conceptual designs of the STCF detector system, and discusses future plans for detector R&D and physics case studies.

DOI ↗

Эксперименты на Супер чарм-тау фабрике

2024 в печати · ARTICLE · ru

В обзоре обсуждается физическая программа нового эксперимента на Супер чарм-тау фабрике, основой которой станет мощный электрон-позитронный коллайдер со светимостью ~1035 см-2с-1 и энергией в системе центра масс в интервале от 3 до 5 ГэВ. Современный детектор, расположенный вокруг точки столкновения пучков, обеспечит новый уровень точности измерений. Продольная поляризация электронного пучка наряду с рекордной светимостью позволят уникальному эксперименту успешно конкурировать с существующими суперфабриками прелести Belle II и LHCb. Обширная физическая программа включает изучение свойств и измерение физических параметров очарованных адронов, τ-лептона, чармония, экзотических состояний, а также исследование рождения лёгких адронов в e+e--аннигиляции и в двухфотонных процессах. Помимо проверки Стандартной модели и прецизионного измерения её параметров, планируется всесторонний поиск Новой физики за её пределами.

DOI ↗

Курсы (2)