Abstract

The branching fraction ratio $\mathcal{R}(D^{*}) \equiv \mathcal{B}(\overline{B}^0 \to D^{*+}\tau^{-}\overline{\nu}_{\tau})/\mathcal{B}(\overline{B}^0 \to D^{*+}\mu^{-}\overline{\nu}_{\mu})$ is measured using a sample of proton-proton collision data corresponding to 3.0\invfb of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode $\tau^{-} \to \mu^{-}\overline{\nu}_{\mu}\nu_{\tau}$. The semitauonic decay is sensitive to contributions from non-Standard-Model particles that preferentially couple to the third generation of fermions, in particular Higgs-like charged scalars. A multidimensional fit to kinematic distributions of the candidate $\overline{B}^0$ decays gives $\mathcal{R}(D^{*}) = 0.336 \pm 0.027(stat) \pm 0.030 (syst)$. This result, which is the first measurement of this quantity at a hadron collider, is 2.1 standard deviations larger than the value expected from lepton universality in the Standard Model.

Figures and captions

Distributions of $m^2_{\rm miss}$ (left) and $ E^{*}_{\mu}$ (right) of the four $ q^{2}$ bins of the signal data, overlaid with projections of the fit model with all normalization and shape parameters at their best-fit values. Below each panel differences between the data and fit are shown, normalized by the Poisson uncertainty in the data. The bands give the $1\sigma$ template uncertainties.	Fig_1.pdf [87 KiB] HiDef png [1012 KiB] Thumbnail [871 KiB] *.C file tex code
Animated gif made out of all figures.	PAPER-2015-025.gif Thumbnail

Tables and captions

Systematic uncertainties in the extraction of $\mathcal{R}( D ^* )$.

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Supplementary Material [file]

Supplementary material full pdf	Supple[..].pdf [718 KiB]
This ZIP file contains supplementary material for the publication LHCb-PAPER-2015-025. The files are: Supplementary.pdf: An overview of the extra figures *.pdf, *.png, *.eps, *.C: The figures in various formats. The *.C files contain the data on the figures.	Fig1.pdf [13 KiB] HiDef png [221 KiB] Thumbnail [185 KiB] *C file
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Created on 27 April 2024.