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Violation in Mixing

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1.5 Determ<strong>in</strong>ation of « 37<br />

1.5 Determ<strong>in</strong>ation of «<br />

The angle « can be extracted from decays � � �ÙÙ, for example decays with two pions <strong>in</strong> the f<strong>in</strong>al state.<br />

The measurement of « is expected to be complicated if the pengu<strong>in</strong> contribution is not negligible.<br />

1.5.1 �È <strong>Violation</strong> us<strong>in</strong>g � decays <strong>in</strong>to non �È eigenstates and Extraction of « ignor<strong>in</strong>g<br />

pengu<strong>in</strong>s<br />

The angle « can be obta<strong>in</strong>ed by the measurements of �È -violat<strong>in</strong>g asymmetries <strong>in</strong> decays to f<strong>in</strong>al states that<br />

can be either �È eigenstates or not. In case of a �È eigenstate, Sec. 1.3 shows the relation between the<br />

asymmetry and the CKM elements. If a s<strong>in</strong>gle weak amplitude contributes to the decay taken <strong>in</strong>to account<br />

and if the pengu<strong>in</strong>s are negligible, then ����È<br />

����È � � and so:<br />

���È � ÁÑ���È ×�Ò ¡Ñ�Ø � (1.58)<br />

Then, ÁÑ� is cleanly related to one of the angle of the unitary triangle. In the particular case of � � ��,<br />

ÁÑ��� � ×�Ò «.<br />

In case the f<strong>in</strong>al state is not a �È eigenstate, four separate amplitudes can be def<strong>in</strong>ed [30]:<br />

� � � � � �� � ����� ��� � � � � � �� � ����� ���<br />

� � � � � � � � �� � �� �� � � � � � � � � � �� � �� �� �<br />

(1.59)<br />

Us<strong>in</strong>g the expressions <strong>in</strong> 1.24 and 1.25 for the physical states � Ô�Ý× Ø and � Ô�Ý× Ø together with the<br />

expressions of the coefficients � Ø and � Ø , one can evaluate the amplitudes:<br />

�<br />

���À��Ô�Ý× Ø � � �<br />

Ø� �ÅØ ¡Ñ�Ø ¡Ñ�Ø ��Å Ó× ���À�� � � ×�Ò � ���À�� �<br />

� �<br />

���À��Ô�Ý× Ø � � �<br />

Ø� �ÅØ ¡Ñ�Ø ¡Ñ�Ø ��Å Ó× ���À�� � � ×�Ò � ���À�� �<br />

where �Å is the phase of � -� mix<strong>in</strong>g com<strong>in</strong>g from Õ�Ô � � ��Å � ��È � . From these time-dependent<br />

amplitude and substitut<strong>in</strong>g Eq. 1.59 one can obta<strong>in</strong> the rates for � Ô�Ý× Ø and � Ô�Ý× Ø decay<strong>in</strong>g <strong>in</strong>to �:<br />

where<br />

� �<br />

�Ô�Ý× Ø � � � � Ø Ò<br />

� ¢<br />

Ó<br />

Ê Ó× ¡Ñ�Ø � ×�Ò �Å �� �� ×�Ò ¡Ñ�Ø<br />

�Ô�Ý× Ø � � � � Ø � ¢<br />

Ò Ó<br />

Ê Ó× ¡Ñ�Ø �×�Ò �Å �� �� ×�Ò ¡Ñ�Ø<br />

� ��� � ����<br />

�<br />

Ê � ��� � ����<br />

���� ����<br />

��<br />

��������<br />

��� � ��� �<br />

�<br />

(1.60)<br />

� (1.61)<br />

�È VIOLATION IN THE �� SYSTEM

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