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Violation in Mixing

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6.5 Analysis choice 159<br />

6.5 Analysis choice<br />

From Monte Carlo and on-resonance data tests, performed <strong>in</strong> both the maximum likelihood fit case and<br />

the count<strong>in</strong>g analysis case, we established that the lowest upper limit can be achieved us<strong>in</strong>g the maximum<br />

likelihood fit method. We choose to perform this maximum likelihood analysis with the � Ó× �Ë� cut set at the<br />

value of ��: this is chosen s<strong>in</strong>ce, <strong>in</strong> this case, we have reduced uncerta<strong>in</strong>ty on the background distributions.<br />

6.6 Results on the Run1 data-set<br />

The f<strong>in</strong>al fit sample conta<strong>in</strong>s 286 candidates and we f<strong>in</strong>d:<br />

Æ×�� � ��<br />

��<br />

��<br />

Æ��� � � ¦ �<br />

The statistical significance of Æ×�� is ���, obta<strong>in</strong>ed by fix<strong>in</strong>g the signal component to zero and record<strong>in</strong>g<br />

the change <strong>in</strong> ÐÓ� Ä.<br />

In order to test the goodness of fit we have generated a set of pseudo-experiments with Æ×�� �<br />

and Æ��� � � : <strong>in</strong> Fig. 6-9 we plot ÐÓ� Ä for each pseudo-experiment. The arrow <strong>in</strong>dicates the value<br />

obta<strong>in</strong>ed from the fit to the Run1 data-set. From the simulation we estimate the probability to f<strong>in</strong>d a greater<br />

value for ÐÓ� Ä to be .<br />

100<br />

80<br />

60<br />

40<br />

20<br />

0<br />

Entries 1000<br />

-5750 -5500 -5250 -5000 -4750 -4500 -4250 -4000 -3750 -3500<br />

Figure 6-9. The value of ÐÓ� Ä for<br />

likelihood value<br />

pseudo-experiments made by Toy MC. The arrow <strong>in</strong>dicates the<br />

result from the fit on the Run1 dataset.<br />

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

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