Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evaluating the charged background rejection requirement in an experiment
  to measure $\rm BR(K_L \to \pi^0 \nu \bar{\nu})$ at the CERN SPS   Measuring the rate at which the long-lived, neutral kaon decays into a
neutral pion, neutrino, and anti-neutrino allows physicists an opportunity to
test precise predictions made by the Standard Model. Differences between
theoretical predictions and experimental measurements may point to new physics.
Not only does the Standard Model predict a very low probability at
approximately 3 $K_L \to \pi^0 \nu \bar{\nu}$ decays in 100 billion $K_L$
decays, but many of the common decays leave false signals in the detector that
look the same as the true signal. Charged decays have been studied to determine
the required detection efficiency necessary to eliminate them. The conclusion
of these studies is that a reduction by a factor of $1/(3\times10^9)$ will be
required to achieve the 10:1 signal to charged background ratio necessary for
the experiment.

18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph