Scalar contributions to $b\to c (u) \tau \nu$ transitions
| Autor: | Celis, Alejandro, Jung, Martin, Li, Xin-Qiang, Pich, Antonio |
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| Rok vydání: | 2016 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1016/j.physletb.2017.05.037 |
| Popis: | We perform a comprehensive analysis of scalar contributions in $b \to c \tau \nu$ transitions including the latest measurements of $R(D^{(*)})$, the $q^2$ differential distributions in $B \to D^{(*)} \tau \nu$, the $\tau$ polarization asymmetry for $B \to D^{*} \tau \nu$, and the bound derived from the total width of the $B_c$ meson. We find that scalar contributions with the simultaneous presence of both left- and right-handed couplings to quarks can explain the available data, specifically $R(D^{(*)})$ together with the measured differential distributions. However, the constraints from the total $B_c$ width present a slight tension with the current data on $B \to D^{*}\tau \nu$ in this scenario, preferring smaller values for $R(D^*)$. We discuss possibilities to disentangle scalar new physics from other new-physics scenarios like the presence of only a left-handed vector current, via additional observables in $B \to D^{(*)}\tau \nu$ decays or additional decay modes like the baryonic $\Lambda_b \to \Lambda_c \tau \nu$ and the inclusive $B \to X_c \tau \nu$ decays. We also analyze scalar contributions in $b \to u \tau \nu$ transitions, including the latest measurements of $B \to \tau \nu$, providing predictions for $\Lambda_b \to p \tau \nu$ and $B \to \pi \tau \nu$ decays. The potential complementarity between the $b \to u$ and $b \to c$ sectors is finally investigated once assumptions about the flavour structure of the underlying theory are made. Comment: 15 pages, 13 figures and 7 tables. More references and discussions added, Tab. VII updated; final version published in the journal |
| Databáze: | arXiv |
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