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 with three c...

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Detalles Bibliográficos
Autores: LHCb Collaboration, Adeva Andany, Bernardo, Álvarez Cartelle, Paula, Borsato, Martino, Chobanova, Veronika, Cid Vidal, Xabier, Dosil Suárez, Álvaro, Fernández Prieto, Antonio, Gallas Torreira, Abraham, García Pardiñas, Julián, Lemos Cid, Edgar, Lucio Martínez, M., Martínez Santos, Diego, Pló Casasús, Máximo, Prisciandaro, James J., Ramos Pernas, Miguel, Romero Vidal, Antonio, Saborido Silva, Juan José, Sanmartín Sedes, Brais, Santamarina Ríos, Cibrán, Vázquez Regueiro, Pablo, Vieites Díaz, María, Vázquez Sierra, Carlos
Tipo de recurso: artículo
Fecha de publicación:2018
País:España
Institución:Universidad de Santiago de Compostela (USC)
Repositorio:Minerva. Repositorio Institucional de la Universidad de Santiago de Compostela
Idioma:inglés
OAI Identifier:oai:minerva.usc.gal:10347/45032
Acceso en línea:https://hdl.handle.net/10347/45032
Access Level:acceso abierto
Palabra clave:Test of lepton flavor
Branching fraction
Electroweak interaction
Leptonic, semileptonic & radiative decays
Descripción
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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