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Violation in Mixing

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176 Analysis of the time-dependent �È -violat<strong>in</strong>g asymmetry <strong>in</strong> � � � � decays<br />

Sample Lepton Kaon NT1 NT2 Untagged<br />

� � MC � ¦ �� �� ¦ �� ��� ¦ � �� ¦ �� � ¦ ��<br />

à � MC �� ¦ �� �� ¦ �� ��� ¦ � ��� ¦ �� � ¦ ��<br />

à à MC �� ¦ �� �� ¦ �� ��� ¦ � ��� ¦ �� ��� ¦ ��<br />

Run 1 � � �� ¦ �� �� ¦ �� ��� ¦ �� � ¦ � �� ¦ ��<br />

Run 2 � � � ¦ �� �� ¦ ��� ��� ¦ � �� ¦ �� ��� ¦ ���<br />

Run1+2Breco � ¦ � ��� ¦ �� �� ¦ � �� ¦ �� � ¦ ��<br />

Table 7-8. Efficiency ( ) for each tag category <strong>in</strong> signal � � Monte Carlo, the Run 1 and Run 2 � �<br />

fit region, and the Run 1 + 2 Breco sample. The latter (highlighted) is used <strong>in</strong> the fit.<br />

7.6 Signal characterization<br />

The tagg<strong>in</strong>g performance and vertex resolution of the tag side <strong>in</strong> a �� event do not depend on the decay<br />

channel of the fully reconstructed � meson. With this assumption, the tagg<strong>in</strong>g efficiencies, dilutions, and<br />

¡Ø resolution function (Ê×��) for ��, Ã�, and Ãà decays are obta<strong>in</strong>ed from the high statistics sample of<br />

fully-reconstructed �’s (Breco sample).<br />

Table 7-8 compares the tagg<strong>in</strong>g efficiency <strong>in</strong> signal Monte Carlo, the Run 1 + 2 Breco sample, and the<br />

� � fit region. The latter is obta<strong>in</strong>ed by float<strong>in</strong>g the signal tag fractions <strong>in</strong> a �È -bl<strong>in</strong>d fit 2 . No significant<br />

difference is observed between different species <strong>in</strong> signal Monte Carlo, and the on-resonance signal region<br />

gives consistent tagg<strong>in</strong>g efficiencies. Table 7-9 summarizes the average dilution and difference for each<br />

category as determ<strong>in</strong>ed <strong>in</strong> the Run 1+2Breco sample.<br />

The signal ¡Ø resolution function is parameterized by the sum of three Gaussians (core, tail, outlier), where<br />

the core bias is a function of the tag category and the error on ¡Ø. Table 7-10 lists the resolution function<br />

parameters obta<strong>in</strong>ed from a fit to the Run 1+2Breco tagged + untagged sample.<br />

2 We bl<strong>in</strong>d the �È parameters by add<strong>in</strong>g a random offset between ¦� and randomly flipp<strong>in</strong>g the sign of the asymmetries.<br />

Breco Run 1 + 2 Breco MC �� MC<br />

Category ��� ¡� ��� ¡� ��� ¡�<br />

Lepton �� ¦ � � � ¦ � �� ��� � � ���� � �<br />

Kaon ���� ¦ � � � ¦ � ��� � � ��� � �<br />

NT1 ���� ¦ � � � ¦ � �� �� � �� �� � � �<br />

NT2 � ¦ � � � � ¦ � �� � � � � � � ��<br />

Table 7-9. Average dilution and difference determ<strong>in</strong>ed from the Run 1+2Breco sample. For comparison<br />

we show the parameters determ<strong>in</strong>ed from Breco and �� MC.<br />

MARCELLA BONA

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