Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Model-Independent Determination of $B_c^+ \to \eta_c\, \ell^+\, \nu$
  Form Factors   We derive model-independent bounds on the form factors for the decay $B_c^+
\to \eta_c\, \ell^+\, \nu$ including full mass effects, i.e. $\ell = e,\, \mu,
\text{ and } \tau$. The bounds are obtained by using the BGL parameterization
for the form factors, and fitting to the preliminary lattice data of the HPQCD
Collaboration. Our main result after bounding the form factors is the Standard
Model (SM) prediction for the ratio of branching fractions $R(\eta_c) =
\mathcal{B}(B_c^+ \to \eta_c\, \tau^+\, \nu_{\tau}) / \mathcal{B}(B_c^+ \to
\eta_c\, \mu^+\, \nu_{\mu})$. We find $R(\eta_c)|_{\text{SM}} =
0.31^{+0.04}_{-0.02}$, and argue that a measurement of $R(\eta_c)$ is within
the reach of LHCb during the high luminosity run of the LHC. In addition, using
the heavy-quark spin symmetry of the $B_c$ meson we relate our results for
$B_c^+ \to \eta_c\, \ell^+\, \nu$ to those for $B_c^+ \to J/\psi\, \ell^+\,
\nu$ yielding the estimate $R(J/\psi)|_{\text{SM}} = 0.26 \pm 0.02$ in good
agreement with other determinations.

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The categories of this paper are: quant-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: math-ph
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The categories of this paper are: q-alg
1
The categories of this paper are: cs
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: math
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The categories of this paper are: funct-an
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The categories of this paper are: adap-org
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The categories of this paper are: econ