Test of lepton flavor universality by the measurement of the B0 →d∗-τ+ντ branching fraction using three-prong τ decays
The ratio of branching fractions R(D∗−) ≡ B(B0 → D∗−τ +ντ )/B(B0 → D∗−µ +νµ) is measured using a data sample of proton-proton collisions collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb−1 . The τ lepton is reconstructed wit...
| Autores: | , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2018 |
| País: | España |
| Institución: | Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) |
| Repositorio: | Recercat. Dipósit de la Recerca de Catalunya |
| OAI Identifier: | oai:recercat.cat:2445/185390 |
| Acceso en línea: | https://hdl.handle.net/2445/185390 |
| Access Level: | acceso abierto |
| Palabra clave: | Hadrons Gran Col·lisionador d'Hadrons Física de partícules Experiments Large Hadron Collider (France and Switzerland) Particle physics |
| Sumario: | The ratio of branching fractions R(D∗−) ≡ B(B0 → D∗−τ +ντ )/B(B0 → D∗−µ +νµ) is measured using a data sample of proton-proton collisions collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb−1 . The τ lepton is reconstructed with three charged pions in the final state. A novel method is used that exploits the different vertex topologies of signal and backgrounds to isolate samples of semitauonic decays of b hadrons with high purity. Using the B0 →D∗−π +π −π + decay as the normalization channel, the ratio B(B0 → D∗−τ +ντ )/B(B0 → D∗−π +π −π +) is measured to be 1.97±0.13±0.18, where the first uncertainty is statistical and the second systematic. An average of branching fraction measurements for the normalization channel is used to derive B(B0 → D∗−τ +ντ ) = (1.42 ± 0.094 ± 0.129 ± 0.054)%, where the third uncertainty is due to the limited knowledge of B(B0 → D∗−π +π −π +). A test of lepton flavor universality is performed using the well-measured branching fraction B(B0 → D∗−µ +νµ) to compute R(D∗−) = 0.291 ± 0.019 ± 0.026 ± 0.013, where the third uncertainty originates from the uncertainties on B(B0 → D∗−π +π −π +) and B(B0 → D∗−µ +νµ). This measurement is in agreement with the Standard Model prediction and with previous measurements. |
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