Test of lepton flavor universality using decays with hadronic 𝜏 channels

Physical Review D - Particles, Fields, Gravitation and Cosmology. 2024. Vol. 108. No. 1. Article 012018.

Aaij R., Abdelmotteleb A. S., Abellan Beteta C., Abudinén F., Ackernley T., Bocharnikov V., Boldyrev A., Hushchyn M., Ryzhikov A., Ratnikov F.

The branching fraction ℬ⁡(𝐵0→𝐷*−⁢𝜏+⁢𝜈𝜏) is measured relative to that of the normalization mode 𝐵0 →𝐷*−⁢𝜋+⁢𝜋−⁢𝜋+ using hadronic 𝜏+ →𝜋+⁡𝜋−⁡𝜋+⁡(𝜋0)⁢¯𝜈𝜏 decays in proton-proton collision data at a center-of-mass energy of 13 TeV collected by the LHCb experiment, corresponding to an integrated luminosity of 2  fb−1. The measured ratio is ℬ⁡(𝐵0→𝐷*−⁢𝜏+⁢𝜈𝜏)/ℬ⁡(𝐵0→𝐷*−⁢𝜋+⁢𝜋−⁢𝜋+) =1.70 ±0.1⁢0+0.11−0.10, where the first uncertainty is statistical and the second is related to systematic effects. Using established branching fractions for the 𝐵0 →𝐷*−⁢𝜋+⁢𝜋−⁢𝜋+ and 𝐵0 →𝐷*−⁢𝜇+⁢𝜈𝜇 modes, the lepton universality test ℛ⁡(𝐷*−) ≡ℬ⁡(𝐵0→𝐷*−⁢𝜏+⁢𝜈𝜏)/ℬ⁡(𝐵0→𝐷*−⁢𝜇+⁢𝜈𝜇) is calculated, ℛ⁡(𝐷*−)=0.247±0.015±0.015±0.012, where the third uncertainty is due to the uncertainties on the external branching fractions. This result is consistent with the Standard Model prediction and with previous measurements.

Keywords: новая физика, Leptons, анализ данных и искусственный интеллект, Hadron colliders, flavor symmetries, Particle decays, глубокое машинное обучение, Particle interactions, Quarks

Publication based on the results of: Neuromorphic optimization of complex experimental setups at dynamically changing quality metrics and boundary conditions (2024)