Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A puzzle in $\bar{B}_{(s)}^0 \to D_{(s)}^{(*)+} \lbrace \pi^-,
  K^-\rbrace$ decays and extraction of the $f_s/f_d$ fragmentation fraction   We provide updated predictions for the hadronic decays $\bar{B}_s^0\to
D_s^{(*)+} \pi^-$ and $\bar{B}^0\to D^{(*)+} K^-$. They are based on
$\mathcal{O}(\alpha_s^2)$ results for the QCD factorization amplitudes at
leading power and on recent results for the $\bar{B}_{(s)} \to D_{(s)}^{(*)}$
form factors up to order ${\cal O}(\Lambda_{\rm QCD}^2/m_c^2)$ in the
heavy-quark expansion. We give quantitative estimates of the matrix elements
entering the hadronic decay amplitudes at order ${\cal O}(\Lambda_{\rm
QCD}/m_b)$ for the first time. Our results are very precise, and uncover a
substantial discrepancy between the theory predictions and the experimental
measurements. We explore two possibilities for this discrepancy:
non-factorizable contributions larger than predicted by the QCD factorization
power counting, and contributions beyond the Standard Model. We determine the
$f_s/f_d$ fragmentation fraction for the CDF, D0 and LHCb experiments for both
scenarios.

10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
24
The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol