Global fit to b → cτν transitions

• Published in: The journal of high energy physics 2019-09, Vol.2019 (9), p.1-45, Article 103
• Main Authors: Murgui, Clara, Peñuelas, Ana, Jung, Martin, Pich, Antonio
• Format: Article
• Language: English
• Subjects: Asymmetry; Beyond Standard Model; Classical and Quantum Gravitation; Differential thermal analysis; Effective Field Theories; Elementary Particles; High energy physics; Physics; Physics and Astronomy; Polarization; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Theoretical Physics; Relativity Theory; String Theory
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP09(2019)103

A bstract We perform a general model-independent analysis of b → cτ ν ¯ τ transitions, including measurements of ℛ D , ℛ D ∗ , their q 2 differential distributions, the recently measured longitudinal D * polarization F L D ∗ , and constraints from the B c → τ ν ¯ τ lifetime, each of which has significant impact on the fit. A global fit to a general set of Wilson coefficients of an effective low-energy Hamiltonian is presented, the solutions of which are interpreted in terms of hypothetical new-physics mediators. From the obtained results we predict selected b → cτ ν ¯ τ observables, such as the baryonic transition Λ b → Λ c τ ν ¯ τ , the ratio ℛ J / ψ , the forward-backward asymmetries A FB D ∗ , the τ polarization asymmetries P τ D ∗ , and the longitudinal D * polarization fraction F L D ∗ . The latter shows presently a slight tension with any new-physics model, such that an improved measurement could have an important impact. We also discuss the potential change due the very recently announced preliminary ℛ D ∗ measurement by the Belle collaboration.