Measurement of an Excess of B -> D(*) Tau Nu Decays and Implications for Charged Higgs Bosons

TL;DR

This paper reports measurements of B meson decays involving tau leptons that exceed Standard Model predictions, suggesting potential new physics but inconsistent with simple charged Higgs models.

Contribution

The study provides improved measurements of R(D) and R(D*) ratios using BaBar data, challenging existing charged Higgs models and exploring implications for new physics.

Findings

Measured R(D) and R(D*) ratios exceed Standard Model expectations.

Results disagree with type II two-Higgs-doublet model at 3.4 sigma.

Certain parameter spaces in type III models remain compatible with findings.

Abstract

Based on the full BaBar data sample, we report improved measurements of the ratios R(D(*)) = B(B -> D(*) Tau Nu)/B(B -> D(*) l Nu), where l is either e or mu. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D) = 0.440 +- 0.058 +- 0.042 and R(D*) = 0.332 +- 0.024 +- 0.018, which exceed the Standard Model expectations by 2.0 sigma and 2.7 sigma, respectively. Taken together, our results disagree with these expectations at the 3.4 sigma level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model. Kinematic distributions presented here exclude large portions of the more general type III two-Higgs-doublet model, but there are solutions within this model compatible with the results.