Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurement of $\mathcal{R}(D)$ and $\mathcal{R}(D^*)$ with a
  semileptonic tagging method   The experimental results on the ratios of branching fractions $\mathcal{R}(D)
= {\cal B}(\bar{B} \to D \tau^- \bar{\nu}_{\tau})/{\cal B}(\bar{B} \to D \ell^-
\bar{\nu}_{\ell})$ and $\mathcal{R}(D^*) = {\cal B}(\bar{B} \to D^* \tau^-
\bar{\nu}_{\tau})/{\cal B}(\bar{B} \to D^* \ell^- \bar{\nu}_{\ell})$, where
$\ell$ denotes an electron or a muon, show a long-standing discrepancy with the
Standard Model predictions, and might hint to a violation of lepton flavor
universality. We report a new simultaneous measurement of $\mathcal{R}(D)$ and
$\mathcal{R}(D^*)$, based on a data sample containing $772 \times 10^6$
$B\bar{B}$ events recorded at the $\Upsilon(4S)$ resonance with the Belle
detector at the KEKB $e^+ e^-$ collider. In this analysis the tag-side $B$
meson is reconstructed in a semileptonic decay mode and the signal-side $\tau$
is reconstructed in a purely leptonic decay. The measured values are
$\mathcal{R}(D)= 0.307 \pm 0.037 \pm 0.016$ and $\mathcal{R}(D^*) = 0.283 \pm
0.018 \pm 0.014$, where the first uncertainties are statistical and the second
are systematic. These results are in agreement with the Standard Model
predictions within $0.2$, $1.1$ and $0.8$ standard deviations for
$\mathcal{R}(D)$, $\mathcal{R}(D^*)$ and their combination, respectively. This
work constitutes the most precise measurements of $\mathcal{R}(D)$ and
$\mathcal{R}(D^*)$ performed to date as well as the first result for
$\mathcal{R}(D)$ based on a semileptonic tagging method.

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The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: patt-sol
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The categories of this paper are: nlin
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The categories of this paper are: quant-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: stat
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The categories of this paper are: funct-an
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The categories of this paper are: dg-ga
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The categories of this paper are: astro-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: cs