Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurement of the $C\!P$ violation parameter $A_\Gamma$ in $D^0 \to
  K^+K^-$ and $D^0 \to \pi^+\pi^-$ decays   Asymmetries in the time-dependent rates of $D^0 \to K^+K^-$ and $D^0 \to
\pi^+\pi^-$ decays are measured in a $pp$ collision data sample collected with
the LHCb detector during LHC Run 1, corresponding to an integrated luminosity
of $3\,\mathrm{fb}^{-1}$. The asymmetries in effective decay widths between
$D^0$ and $\overline{D}^0$ decays, sensitive to indirect $CP$ violation, are
measured to be $A_\Gamma(K^+ K^-) = (-0.30 \pm 0.32 \pm 0.10)\times 10^{-3}$
and $A_\Gamma(\pi^+\pi^-) = (0.46 \pm 0.58 \pm 0.12)\times 10^{-3}$, where the
first uncertainty is statistical and the second systematic. These measurements
show no evidence for $C\!P$ violation and improve on the precision of the
previous best measurements by nearly a factor of two.

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The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int