Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: $B$ Meson Decay Constants $f_{B_c}$, $f_{B_s}$ and $f_B$ from QCD Sum
  Rules   Finite energy QCD sum rules with Legendre polynomial integration kernels are
used to determine the heavy meson decay constant $f_{B_c}$, and revisit $f_B$
and $f_{B_s}$. Results exhibit excellent stability in a wide range of values of
the integration radius in the complex squared energy plane, and of the order of
the Legendre polynomial. Results are $f_{B_c} = 528 \pm 19$ MeV, $f_B = 186 \pm
14$ MeV, and $f_{B_s} = 222 \pm 12$ MeV.

30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
4
The categories of this paper are: cond-mat
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc