$B$ anomalies with unparticles

Abstract

We analyze the $B$ anomalies associated with the $B\to D^{(*)}\tau\nu$ decays in the unparticle model. The fraction of the branching ratios $R(D^{(*)})$ and other parameters related to the polarization are fitted to the experimental data by minimizing $\chi^2$. The best-fit values are $R(D)_{\rm best}=0.371$ and $R(D^*)_{\rm best}=0.266$ which are still larger than the standard model predictions. We find that our results safely render the branching ratio ${\rm Br}(B_c\to\tau\nu)$ below $10\%$.