Unparticle effects on $B\to D^{(*)}\tau\nu$

TL;DR

This paper investigates the potential influence of unparticles on B meson decays involving tau leptons, fitting recent experimental data to assess the viability of unparticle physics as an explanation for observed anomalies.

Contribution

It provides a detailed fit of unparticle effects to B decay data, showing that unparticles can still account for deviations from the Standard Model within current experimental constraints.

Findings

Unparticle effects can accommodate current B decay anomalies.

Best-fit values for R(D) and R(D*) are still above Standard Model predictions.

Unparticle contributions do not violate constraints on B_c→τν branching ratio.

Abstract

We examine the possible unparticle effects on $R(D^{(*)})$ associated with $B\to D^{(*)}\tau\nu$ decays by minimum-$\chi^2$ fitting. Recent measurements from Belle and LHCb are included in this analysis. While it is true that the new experimental results of $R(D^{(*)})$ get closer to the standard model predictions, there are still rooms for new physics and unparticles are also one possibility. Our best-fit values are $R(D)=0.456$ and $R(D^*)=0.270$, which are still far from the standard model values by more than ($R(D)$) or almost ($R(D^*)$) $2\sigma$. We also find that the unparticle effects are quite safe to render the branching ratio ${\rm Br}(B_c\to\tau\nu)$ less than 10\%.