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Violation in Mixing

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5.4 Background Suppression and PDF Parameterization 131<br />

5.4.5 Efficiency<br />

In summary, after the standard selection, the follow<strong>in</strong>g cuts are applied:<br />

¯ �ÑÃË ÑÈ��� � � Å�Î�<br />

¯ Ø ÃË ��Ø ÃË<br />

¯ PID cuts<br />

� �<br />

Monte Carlo is used to estimate the efficiency of different cuts with the exceptions of track reconstruction,<br />

the Ã Ë reconstruction and the Ã Ë <strong>in</strong>variant mass cut. In this last case, we consider the efficiency (and the<br />

relative error) found <strong>in</strong> the � � Ã Ë � (see Section 5.2). Table 5-2 summarizes the efficiencies of the<br />

different cuts.<br />

To correct the MC f<strong>in</strong>al efficiency for the track<strong>in</strong>g uncerta<strong>in</strong>ty (see Sec. 4.5), we use the results from<br />

detailed studies on various control samples [61]: the correction factor comes out to be �ØÖ� � ��� with an<br />

uncerta<strong>in</strong>ty of � per track.<br />

In the Ã Ë case, the correction on the efficiency is done on the base of the correction tables from <strong>in</strong>clusive à Ë<br />

reconstruction described <strong>in</strong> Sec. 3.3.4: the correction factor is � � ¦ � �. No correction is applied for the<br />

Ã Ë daughter tracks s<strong>in</strong>ce they are taken from the list ChargedTracks and the Track<strong>in</strong>g Efficiency Work<strong>in</strong>g<br />

Group has found agreement with MC, but the uncerta<strong>in</strong>ty per Ã Ë ( per ChargedTracks track) has to<br />

be taken <strong>in</strong>to account to evaluate the error on the efficiency.<br />

Table 5-2. Efficiencies of the cuts for the decay mode � � Ã Ë � as determ<strong>in</strong>ed from signal MC only.<br />

Cut Efficiency Ã Ë � Efficiency Ã Ë Ã<br />

reco + tag bits + Ê +<br />

Sph + GoodTracksAccLoose ���� � �<br />

� Ó× �Ë� � �� ��� ���<br />

�ÑÃË ÑÈ��� � � Å�Î ��� ���<br />

Ø ÃË ��Ø ÃË<br />

� � ���� ����<br />

� � � �� � �<br />

proton veto ��� ����<br />

ҭ � � ���� ���<br />

all previous cuts � � ���<br />

MEASUREMENT OF BRANCHING FRACTIONS FOR � ¦ � Ã � ¦ DECAYS

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