Search for Bs0 → ℓ∓τ± with the Semi-leptonic Tagging Method at Belle

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Search for Bs0 → ℓ∓τ± with the Semi-leptonic Tagging Method at Belle

Journal of High Energy Physics. 2023. Article 178.

Nayak L., Aihara H., Aushev T., Bodrov D., Pakhlov P., Pakhlova G., Uglov T.

We present a search for the lepton-flavor-violating decays B0s→ℓ∓τ±, where ℓ=e,μ, using the full data sample of 121 fb−1 collected at the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We use B0sB¯¯¯¯0s events in which one B0s meson is reconstructed in a semileptonic decay mode and the other in the signal mode. We find no evidence for B0s→ℓ∓τ± decays and set upper limits on their branching fractions at 90% confidence level as B(B0s→e∓τ±)<14×10−4 and B(B0s→μ∓τ±)<7.3×10−4. Our result represents the first upper limit on the B0s→e∓τ± decay rate.

Research target: Physics

Publication based on the results of:

Development of new methods for searching for physics beyond the Standard Model in experiments at the Super Charm-Tau Factory and Belle at the KEKB B-Factory (2023)

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Modification of perovskite-type oxides is an effective way to develop functional materials with advanced properties. The effects of cerium introduction into the A sublattice of La0.5Sr0.5FeO3−δ and variation of La:Sr ratio on the defect structure and charge transfer characteristics were studied in this work. The LaxSr0.85−xCe0.15FeO3−δ oxides were found to be single-phase with cubic (x = 0.1) and orthorhombic ...

Added: June 26, 2026

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Polkin A., Skvortsov M., Physical Review B: Condensed Matter and Materials Physics 2026 Vol. 113 Article 174516

We develop a full microscopic theory for the optical conductivity 𝜎⁡(𝜔) of a dirty current-carrying superconductor. Within the Keldysh sigma model formalism, we obtain the general analytical expression for 𝜎⁡(𝜔), applicable for arbitrary frequency 𝜔, temperature 𝑇, and dc supercurrent 𝐼. In addition to altering the usual Mattis-Bardeen conductivity 𝜎1⁡(𝜔), a finite supercurrent introduces two new contributions: 𝜎qp2⁡(𝜔) from quasiparticle redistribution and 𝜎SH2⁡(𝜔) from the amplitude ...

Added: June 25, 2026

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Skvortsov M., Artem Polkin, Physical Review B: Condensed Matter and Materials Physics 2026 Vol. 113 No. 10 Article 100502

A dissipationless supercurrent state in superconductors can be destroyed by thermal fluctuations. Thermally activated phase slips provide a finite resistance of the sample and are responsible for dark counts in superconducting single-photon detectors. The activation barrier for a phase slip is determined by a space-dependent saddle-point (instanton) configuration of the order parameter. In the one-dimensional ...

Added: June 25, 2026

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The authors study the temporal evolution of polarized spectra of emissions from spinor exciton‒ polariton condensates in double tunnel-coupled potential traps inside a high-Q GaAs/AlAs microcavity at 2 K upon resonance laser pumping with picosecond pulses at times of up to 1.5 ns. The period of the condensates’ spin relaxation in a double trap is estimated as τs ...

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И.А. Бакунина, В.Ф. М., А.В. Ш. et al., Геомагнетизм и аэрономия 2025 Т. 65 № 9 С. 1363–1373

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Added: June 22, 2026

Моделирование влияния температуры на взаимодействие катода с тонкой диэлектрической пленкой и плазмы тлеющего газового разряда в смеси аргона и паров ртути

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Added: June 20, 2026

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Chertenkov V. I., Shchur L., Lobachevskii Journal of Mathematics 2026 Vol. 47 No. 2 P. 720–727

Supervised machine learning is successfully applied to the study of critical phenomena and allows us to obtain a numerical estimate of the phase transition temperature and the correlation length exponent. We discuss the influence of possible systematic errors, as well as statistical errors, on the accuracy of such numerical estimates. Errors in the training and ...

Added: June 16, 2026

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Батурин А. С., Гаврилов В. Р., Иванов А. В. et al., Измерительная техника 2026 Т. 75 № 2 С. 14–28

28 декабря 2025 года Всероссийскому научно-исследовательскому институту оптико-физических измерений (ВНИИОФИ) исполнилось 60 лет. За прошедшие десятилетия институт выполнил значительное количество научных исследований, разработал и поставил потребителям тысячи высокоточных средств оптико-физических измерений (включая эталонное оборудование). В статье представлены наиболее значимые для метрологического обеспечения оптико-физических измерений результаты научно-исследовательских работ, выполненных ВНИИОФИ за период 2016–2025 гг. ...

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Вишняков Г. Н., Левина Э. Ю., Minaev V., Измерительная техника 2025 Т. 74 № 2 С. 20–27

Качество формируемого оптической системой изображения определяется её частотно-контрастной характеристикой или коэффициентами передачи модуляции на различных пространственных частотах. Для обеспечения единства измерений коэффициентов передачи модуляции и создания эталонной базы по воспроизведению, хранению и передаче единицы коэффициента передачи модуляции усовершенствован Государственный первичный эталон единиц оптической силы очковой оптики ГЭТ 205-2013 в части воспроизведения единицы коэффициентов передачи модуляции ...

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Impact of heat treatment on microstructure and mechanical properties of additively manufactured aluminum bronze

Filippova A. V., Yurchenko N. Y., Smirnov S. A. et al., Journal of Alloys and Compounds 2026 No. 1074 Article 189162

This study investigates the effects of post-processing heat treatment at 300–500 °C on the microstructure, hardness, and tensile properties of laser powder bed fusion (PBF-LB) processed Al-bronze processed with energy densities (ED) in the range of 125–938 J/mm3. In the as-printed state, sharp needle-like α + β′ laths form at lower ED whereas with increasing ED, the β′ ...

Added: June 12, 2026

Спонтанное образование скин-слоя в воде с деформацией ОН-полосы КР вкладом компоненты льда 3200 см-1

Першин С. М., Степанов Е. В., Артемова Д. Г. et al., Письма в Журнал экспериментальной и теоретической физики 2026 Т. 123 № 6 С. 383–390

Открыто спонтанное образование в течение 4 ч скин-слоя дистиллированной воды толщиной до 3 мм при комнатной температуре с новыми свойствами. Обнаружены деформация ОН-полосы комбинационного рассеяния вкладом компоненты льда ( 3200 см-1), снижение коэффициента упругого рассеяния и его флуктуаций, а также увеличение на 20 капиллярах. Восстановление слоя после обогащения воздухом в результате перемешивания указывает на стабильность ...

Added: June 8, 2026

Innovations in Information and Decision Sciences. Proceedings of the 13th International Conference on Frontiers in Intelligent Computing: Theory and Applications (FICTA 2025), Volume 4

Springer, 2026.

The book presents the proceedings of the 13th International Conference on Frontiers of Intelligent Computing: Theory and Applications (FICTA 2024), held at Intelligent Systems Research Group (ISRG), London Metropolitan University, London, United Kingdom, during June 6–7, 2025. Researchers, scientists, engineers and practitioners exchange new ideas and experiences in the domain of intelligent computing theories with ...

Added: June 8, 2026

Relativistic effects in the interaction of electrons with a slow extraordinary wave

N.S. Artekha, D.R. Shklyar, Physics of Plasmas 2026 Vol. 33 No. 6 Article 062105

The peculiarities of resonant interaction between slow extraordinary (SE) waves and relativistic electrons have been studied. General equations of motion of relativistic electrons in the field of SE wave and a uniform ambient magnetic field are derived. Conditions of applicability of the isolated resonance approximation are elucidated. In this approximation, the equations of motion are reduced to one-dimensional set of ...

Added: June 6, 2026

Structural and broadband radio-frequency properties of InGaZnO4 nanoparticles synthesized by gel decomposition method

Zirnik G., Ostovari Moghaddam A., Zhukov S. et al., Journal of Materials Science: Materials in Electronics 2026 Vol. 37 Article 738

In regards to the advances in InGaZnO for flexible transistors applications, herein for the first time we measure the broadband radio-frequency range (10 Hz to 1 MHz) dielectric permittivity ε′ and electrical conductivity σ of InGaZnO4 nanoparticle layers at different temperatures ranging from 10 to 300 K. The InGaZnO4 nanoparticles prepared by metal–nitrate–glycol gel decomposition method exhibited ...

Added: June 6, 2026

Wave dynamics within the Whitham-Ostrovsky equation

Flamarion M. V., Pelinovsky E., Nonlinear Dynamics 2026 Vol. 114 Article 784

In this article, we investigate wave packet and solitary wave dynamics in the Whitham–Ostrovsky (WO) equation. By means of a multiple-scales expansion, we formally derive a nonlinear Schrödinger (NLS) equation governing the envelope evolution.The corresponding modulational stability diagram is then obtained using the Lighthill criterion. We show that sufficiently large values of the low-frequency dispersive term render ...

Added: June 5, 2026

Green synthesis of Bi-functional silica nanoparticles towards highly efficient photocatalysis and antibacterial application

Hazarika A. P., Das A., Das S. K. et al., Physica B: Condensed Matter 2026 Vol. 738 Article 418803

Lemon grass (Cymbopogon citratus, LG-SiO2), horsetail (Equisetum debile, SG-SiO2), and cassava leaves (Manihot esculenta, CL-SiO2) were used to green-synthesize silica (SiO2) nanoparticles (NPs). While LG-SiO2 and SG-SiO2 had strong (101) peaks and a large 22° amorphous peak, XRD of CL-SiO2 verified crystallinity. LG-SiO2 (agglomerated porous), SG-SiO2 (rectangular-cube agglomerates), and CL-SiO2 (flake agglomerates) had different morphologies. The TEM image of LG-SiO2 revealed agglomerated ...

Added: June 4, 2026

Measurement of branching fractions and decay asymmetry parameters for Λc+ → Λh+ and Λc+ → Σ0h+ (h=K,π), and search for CP violation in baryon decays

Kinoshita K., Aihara H., Aushev T. et al., Science Bulletin 2023

We report a study of Λ+c→Λh+ and Λ+c→Σ0h+ (h=K,π) decays based on a data sample of 980~fb−1 collected with the Belle detector at the KEKB energy-asymmetric e+e− collider. The first results of direct CP asymmetry in two-body singly Cabibbo-suppressed (SCS) decays of charmed baryons are measured, AdirCP(Λ+c→ΛK+)=+0.021±0.026±0.001 and AdirCP(Λ+c→Σ0K+)=+0.025±0.054±0.004. We also make the most precise measurement of the decay asymmetry parameters (α) for the four modes of ...

Added: December 1, 2023

Evidence of B0 → pΣ−π− at Belle

Chang C. -., Wang M. -., Adachi I. et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2023 Vol. 108 No. 5 Article 052011

We search for the B0→p¯Σ0π− decay with ¯Σ0→¯Λγ, where the γ is not measured, using a data sample corresponding to an integrated luminosity of 711 fb−1 which contains 772×106 B¯B pairs, collected around the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We measure for the first time the B0→p¯Σ0π− branching fraction to be B(B0→p¯Σ0π−)=(1.17+0.43−0.40(stat)±0.07(syst))×10−6 with a significance of 3.0σ. We simultaneously measure the branching fraction for the related channel B0→p¯Λπ− with much ...

Added: December 1, 2023

Angular analysis of the low K+K− mass enhancement in B+→ K+K−π+ decays

Hsu C. -., Sevior M. E., Adachi I. et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2023 Vol. 107 No. 3 Article 032013

We study the decay B+→K+K−π+ and investigate the angular distribution of K+K− pairs with invariant mass below 1.1 GeV/c2. This region exhibits both a strong enhancement in signal and very large direct CP violation. We construct a coherent sum model for the angular distribution of S- and P-wave, and report the ratio of their amplitudes, the relative phase and the forward-backward asymmetry. We also report ...

Added: December 1, 2023

First Measurement of the B+ → π + π0π0 Branching Fraction and CP Asymmetry

Lai Y. -., Adachi I., Aihara H. et al., Physical Review Letters 2023 Vol. 130 No. 18 Article 181804

We study B+→π+π0π0 using 711 fb−1 of data collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We measure an inclusive branching fraction of (19.0±1.5±1.4)×10−6 and an inclusive CP asymmetry of (9.2±6.8±0.7)%, where the first uncertainties are statistical and the second are systematic, and a B+→ρ(770)+π0 branching fraction of (11.2±1.1±0.9+0.8−1.6)×10−6, where the third uncertainty is due to possible interference with B+→ρ(1450)+π0. We present the first observation of ...

Added: November 30, 2023

First measurement of the Q2 distribution of X(3915) single-tag two-photon production

Teramoto Y., Uehara S., Adachi I. et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2023 Vol. 108 No. 1 Article 012004

We report the first measurement of the Q2 distribution of X(3915) produced by single-tag two-photon interactions. The decay mode used is X(3915)→J/ψω. The covered Q2 region is from 1.5 (GeV/c)2 to 10.0 (GeV/c)2. We observe 7.9±3.1(stat.)±1.5(syst.) events, where we expect 4.1±0.7 events based on the Q2=0 result from the no-tag two-photon process, extrapolated to higher Q2 region using the cc¯ model of Schuler, Berends, and van Gulik. The shape of the distribution is ...

Added: November 30, 2023

Study of the lineshape of X(3872) using B decays to D0D*0K

Hirata H., Adachi I., Aushev T. et al., Physical Review D - Particles, Fields, Gravitation and Cosmology 2023 Vol. 107 No. 11 Article 112011

We present a study of the X(3872) lineshape in the decay B→X(3872)K→D0¯D*0K using a data sample of 772×106 B¯B pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. The peak near the threshold in the D0¯D*0 invariant mass spectrum is fitted using a relativistic Breit-Wigner lineshape. We determine the mass and width parameters to be mBW=3873.71+0.56−0.50(stat)±0.13(syst) MeV/c2 and ΓBW=5.2+2.2−1.5(stat)±0.4(syst) MeV, respectively. The branching fraction is found ...

Added: November 30, 2023

Search for the Lepton Flavor Violating Decays B+ → K+τ±ℓ∓ (ℓ=e,μ) at Belle

Watanuki S., Marino G. d., Trabelsi K. et al., Physical Review Letters 2023 Vol. 130 No. 26 Article 261802

We present a search for the lepton-flavour-violating decays B+→K+τ±ℓ∓, with ℓ=(e,μ), using the full data sample of 772×106 BB¯¯¯¯ pairs recorded by the Belle detector at the KEKB asymmetric-energy e+e− collider. We use events in which one B meson is fully reconstructed in a hadronic decay mode. We find no evidence for B±→K±τℓ decays and set upper limits on their branching fractions at the 90% confidence ...

Added: November 30, 2023