Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The width difference in \bbm\ at order $\alpha_s$ and beyond   We complete the calculation of the element $\Gamma_{12}^q$ of the decay
matrix in $B_q-\bar{B}_q$ mixing, $q=d,s$, to order $\alpha_s$ in the leading
power of the Heavy Quark Expansion. To this end we compute one- and two-loop
contributions involving two four-quark penguin operators. Furthermore, we
present two-loop QCD corrections involving a chromomagnetic operator and either
a current-current or four-quark penguin operator. Such contributions are of
order $\alpha_s^2$, i.e. next-to-next-to-leading-order. We also present
one-loop and two-loop results involving two chromomagnetic operators which are
formally of next-to-next-to-leading and next-to-next-to-next-to-leading-order,
respectively. With our new corrections we obtain the Standard-Model prediction
$\Delta\Gamma_s/\Delta M_s= (5.20\pm 0.69)\cdot 10^{-3}$ if $\Gamma_{12}^s$ is
expressed in terms of the $\overline{\rm MS}$ b-quark mass, while we find
$\Delta \Gamma_s/\Delta M_s= (4.70\pm 0.96)\cdot 10^{-3}$ instead for the use
of the pole mass.

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The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
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The categories of this paper are: acc-phys
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
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The categories of this paper are: solv-int
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: cs
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The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat