Measurement of an excess of [¯ over B] → D[superscript (*)]τ[superscript -]ν[¯ over v][subscript τ] decays and implications for charged Higgs bosons

Abstract

Based on the full BABAR data sample, we report improved measurements of the ratios R(D) = B([¯ over B] → D[subscript τ][superscript −][¯ over v][subscript τ])/B([¯ over B] → Dℓ[superscript −][¯ over v]ℓ) and R(D[superscript *]) = B([¯ over B] → D[superscript *]τ[superscript −][¯ over v][subscript τ])/B([¯ over B] → D[superscript *]ℓ[superscript −][¯ over v][subscript ℓ]), where ℓ refers to either an electron or muon. 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[superscript *]) = 0.332 ± 0.024 ± 0.018, which exceed the standard model expectations by 2.0σ and 2.7σ, respectively. Taken together, the results disagree with these expectations at the 3.4σ 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.