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On the Flavor Problem in Strongly Coupled Theories - THEP Mainz

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2.6. Four Fermion Interactions 89<br />

<strong>in</strong>duced <strong>in</strong>teractions aris<strong>in</strong>g from <strong>the</strong> exchange of a Z-boson read<br />

H (Z) 4πα<br />

eff =<br />

s2 wc2 w m2 �<br />

1 +<br />

Z<br />

m2 Z<br />

2M 2 �<br />

1 −<br />

KK<br />

1<br />

�<br />

m4 Z + O<br />

2L M 4 ���<br />

(2.186)<br />

KK<br />

× �<br />

S(¯qi, qj; ¯q ′ k , q′ l ) � ¯qLγ µ T q<br />

3 (1 − δQ)qL + ¯qRγ µ T q<br />

3 δqqR − s 2 w Qq ¯qγ µ q �<br />

q,q ′<br />

+ 4παL<br />

�<br />

�<br />

×<br />

+<br />

s 2 wc 2 w M 2 KK<br />

�<br />

q,q ′<br />

�<br />

× ¯q ′ LγµT q′<br />

3 (1 − δQ ′)q′ L + ¯q ′ RγµT q′<br />

3 δq ′q′ R − s 2 w Qq ′ ¯q′ γµq ′�<br />

S(¯qi, qj; ¯q ′ k , q′ l )<br />

�<br />

− ¯qLγµT q<br />

3 (1 − δQ)qL + ¯qRγµT q<br />

3 δqqR − s 2 �<br />

w Qq ¯qγµq<br />

¯q ′ Lγ µ T q′<br />

3 (∆Q ′ − εQ ′)q′ L + ¯q ′ Rγ µ T q′<br />

3 εq ′q′ R − s 2 w Qq ′<br />

�<br />

¯qLγ µ T q<br />

3 ( � ∆Q − �εQ)qL + ¯qRγ µ T q<br />

3 �εqqR − s 2 w Qq<br />

� ′<br />

¯q Lγ µ ∆Q ′q′ L + ¯q ′ Rγ µ ∆q ′q′ �<br />

R<br />

�<br />

�<br />

¯qLγ µ � ∆QqL + ¯qRγ µ � ∆qqR<br />

�<br />

⊗ ¯q ′ LγµT q′<br />

3 ( � ∆Q ′ − �εQ ′)q′ L + ¯q ′ RγµT q′<br />

3 �εq ′q′ R − s 2 w Qq ′<br />

�<br />

¯q ′ Lγµ � ∆Q ′q′ L + ¯q ′ Rγµ � ∆q ′q′ � �<br />

R<br />

�<br />

.<br />

Here, <strong>the</strong> δ and ε matrices appear due to <strong>the</strong> non-vectorial coupl<strong>in</strong>g of <strong>the</strong> Z. Also,<br />

by writ<strong>in</strong>g mZ, we implicitly assume <strong>the</strong> RS corrections (2.111) to be absorbed. Here<br />

and <strong>in</strong> <strong>the</strong> follow<strong>in</strong>g, mW,Z ≡ mRS . To a good approximation one can neglect <strong>the</strong>se<br />

W,Z<br />

terms and ends up with a considerably simpler expression, which holds up to order<br />

v4 /M 4 KK corrections,<br />

H (Z)<br />

eqq = 4πα<br />

s2 wc2 w m2 �<br />

1 +<br />

Z<br />

m2 Z<br />

<strong>in</strong> which<br />

− 8πα<br />

s 2 wc 2 w m 2 Z<br />

− 4παL<br />

s 2 wc 2 w M 2 KK<br />

�<br />

q<br />

2M 2 KK<br />

�<br />

q<br />

+ 4παL<br />

s2 wc2 w M 2 �<br />

KK q,q ′<br />

S(¯q, q; ¯q ′ , q ′ )<br />

J µ<br />

Z<br />

�<br />

1 − 1<br />

�<br />

m4 Z + O<br />

2L M 4 ���<br />

S(¯q, q; ¯q<br />

KK<br />

′ , q ′ )J µ<br />

Z JZµ<br />

S(¯qi, qj; ¯q ′ k , q′ l ) [¯qLγ µ T q<br />

3 δQqL − ¯qRγ µ T q<br />

3 δqqR] JZµ<br />

≡ �<br />

q<br />

� �<br />

(2.187)<br />

S(¯q, q; ¯q ′ , q ′ � �T q<br />

) 3 − s2 �<br />

w Qq ¯qLγ µ ∆QqL − s 2 w Qq ¯qRγ µ �<br />

∆qqR JZµ<br />

� � �T q<br />

3 − s2 w Qq<br />

� ¯qLγ µ � ∆QqL − s 2 w Qq ¯qRγ µ � ∆qqR<br />

� �<br />

⊗ T q′<br />

3 − s2w Qq ′<br />

�<br />

¯q ′ Lγµ � ∆Q ′q′ L − s 2 w Qq ′ ¯q′ Rγµ � ∆q ′q′ �<br />

R<br />

�<br />

,<br />

�� q<br />

T3 − s2 �<br />

w Qq ¯qLγ µ qL − s 2 w Qq ¯qRγ µ �<br />

qR . (2.188)<br />

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