28.12.2012 Views

Violation in Mixing

Violation in Mixing

Violation in Mixing

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

1.2 Neutral � Mesons 9<br />

Apply<strong>in</strong>g the Wigner-Weisskopf method [10], we <strong>in</strong>troduce an approximation by leav<strong>in</strong>g out <strong>in</strong> Eq. 1.1,<br />

the last term: this corresponds to neglect<strong>in</strong>g the weak <strong>in</strong>teraction for those particles to which the <strong>in</strong>itial<br />

mesons can decay. Therefore the decay products are considered to be stable. With this method and with<br />

this approximation, we can write these two equations as functions of �� Ø that are a f<strong>in</strong>ite number Ò of<br />

functions. Def<strong>in</strong><strong>in</strong>g the vector:<br />

� Ø �<br />

�<br />

�<br />

�<br />

�<br />

�<br />

� Ø<br />

�<br />

�<br />

�<br />

�Ò Ø<br />

�<br />

�<br />

�<br />

�<br />

�<br />

and where Ï is def<strong>in</strong>ed as:<br />

Ï � Ï�� �<br />

� that satisfies � Ø �� �ÏØ « � where « �<br />

� ���À�� � È �<br />

���À���� � �À � � �<br />

� �� È<br />

and go<strong>in</strong>g back to the Schröd<strong>in</strong>ger picture, one obta<strong>in</strong>s:<br />

�<br />

�<br />

�<br />

�<br />

�<br />

«<br />

�<br />

�<br />

�<br />

« Ò<br />

�<br />

�<br />

�<br />

�<br />

�<br />

�<br />

� « Ø �<br />

�� È � Æ � ��<br />

�<br />

� � �À � � �� � �À � � � �<br />

(1.2)<br />

« Ø �� �� Ø � Ø �� �� ÏØ � �� �ÀØ � (1.3)<br />

where À � � Ï. This matrix À is called the non-Hermitian mass (or energy) matrix. At this po<strong>in</strong>t,<br />

One can def<strong>in</strong>e two Hermitian matrices Å � Å Ý and � Ý :<br />

Å � À À Ý<br />

��À À Ý from which one obta<strong>in</strong>s À � Å<br />

The elements of these matrices can be extracted from Eq. 1.2:<br />

Å �� � � Æ �� � � �À � � � �<br />

�� � �<br />

�<br />

�<br />

� � �À � � �� � �À � � �<br />

�<br />

� �� È<br />

�Æ � �� � � �À � � �� � �À � � �<br />

The �ÈÌ <strong>in</strong>variance guarantees the equality À�� � À�� with the state � � � that represents the charge<br />

conjugate of � � � (they both belong to the same eigenvalue): <strong>in</strong> fact, from<br />

� � �À� � � � � � � �ÈÌ �ÈÌ À �ÈÌ �ÈÌ ��� � ���ÈÌ� ���À� � � � � � �À� � ��<br />

suppos<strong>in</strong>g �ÈÌ À �ÈÌ � Àand know<strong>in</strong>g that �ÈÌ �ÈÌ � (therefore the eigenvalues can be<br />

���ÈÌ� � exclusively) and that �ÈÌ��� � ��ÈÌ���.<br />

�<br />

�È VIOLATION IN THE �� SYSTEM

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!