Violation in Mixing

3.3 Studies on data 79
19.5° BINS FROM 9° (157 mrad) TO 165°
0.1%
0.1% 0.2%
0.1% .1% .6%1% 1.2% 1% 0.1%
2.5% 13.1%
5.4% 8.9% 11% 14.2% 18.4% 17.1%
Figure 3-2. Fraction of Ã Ë decaying in several regions of the tracking acceptance.
1. The Ã Ë is not in the KsDefault list. The possible reasons are:
(a) one or both pions are outside of the geometrical acceptance
(b) both pions are within the acceptance but there is a reconstruction problem
i. at least one pion is not reconstructed
ii. reconstructed ÃË mass is not in the mass window (see section 3.1.1)
iii. bad vertex reconstruction
(c) problem with MC truth association
r=20 cm
2. The Ã Ë is in the KsDefault list. To understand the vertex fit, we have divided the sample into à Ë
with low and high vertex � probability and searched for differences.
Table 3-1 shows the fraction of candidates which are lost because of reconstruction and angular acceptance.
Out of the Ã Ë that fall inside the acceptance, ��� of them is actually reconstructed. Only ��� of the
Ã Ë candidates decaying within the acceptance are not reconstructed although their daughters have been
reconstructed
3.3 Studies on data
The main goal of this analysis is though to provide a way to correct the efficiencies found on Monte Carlo
samples to agree with data. In order to understand the efficiency 2 on the data, our study has been performed
on a sample of consistently processed data.
2 In the following, if not otherwise stated, efficiencies are quoted on the whole solid angle: they include acceptance.
60
cm
40
cm
Ã Ë RECONSTRUCTION AND EFFICIENCY STUDIES