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On the Flavor Problem in Strongly Coupled Theories - THEP Mainz

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192 Appendix D. Higgs Potential for <strong>the</strong> Extended Scalar Sector<br />

structure only appears <strong>in</strong> <strong>the</strong> terms which mix all three fields,<br />

Q ijkl<br />

ABCD (x) ≡ xiTr � � � �<br />

TATB Tr TCTD + xjTr � �<br />

TATDTCTB<br />

(D.3)<br />

+xkTr � � � �<br />

TATD Tr TBTC + xlTr � �<br />

TATBTCTD ,<br />

P ij<br />

ABCD (y) ≡ yiTr � � � �<br />

TATB Tr TCTD + yjTr � �<br />

TATDTBTC ,<br />

� �2 Nc<br />

RABC ≡ δA0δB0δC0 −<br />

2<br />

Nc � � �<br />

Tr TATB δC0 + Tr<br />

2<br />

� �<br />

TATC δB0 + Tr � � �<br />

TCTB δA0<br />

+ Tr � � � �<br />

TATBTC + Tr TBTATC .<br />

The Higgs sector comprises 3 mass terms, 2 × 4 real parameters describ<strong>in</strong>g selfcoupl<strong>in</strong>gs<br />

of <strong>the</strong> bitriplets (<strong>the</strong> P structures), one parameter describ<strong>in</strong>g <strong>the</strong> selfcoupl<strong>in</strong>gs<br />

of <strong>the</strong> color s<strong>in</strong>glet, 6 real and 3 complex parameters from mix<strong>in</strong>g between<br />

<strong>the</strong> color s<strong>in</strong>glet and one of <strong>the</strong> bitriplets as well as 12 f-terms which describe mix<strong>in</strong>g<br />

between <strong>the</strong> colored scalars (<strong>the</strong> Q structures). This makes for a total of 36 real<br />

parameters.<br />

It is straightforward to solve <strong>the</strong> extremal conditions, which are given by<br />

∂V (vℓ, vu, vd)<br />

= 0 ,<br />

∂vu<br />

∂V (vℓ, vu, vd)<br />

= 0 ,<br />

∂vd<br />

∂V (vℓ, vu, vd)<br />

= 0 , (D.4)<br />

∂vℓ<br />

and can be used to elim<strong>in</strong>ate three parameters. For a general Higgs potential, it is<br />

however not possible to analytically proof that this extremum is a m<strong>in</strong>imum. The<br />

reason is, that a m<strong>in</strong>mum is only obta<strong>in</strong>ed if <strong>the</strong> Hessian of <strong>the</strong> potential is positive<br />

def<strong>in</strong>ite. The potential will however give rise to 8 + 4 Goldstone bosons, which<br />

correspond to zeros on <strong>the</strong> diagonal of <strong>the</strong> Hessian (<strong>in</strong> blockdiagonal form). As a<br />

consequence it is a numerical problem to m<strong>in</strong>imize <strong>the</strong> potential. <strong>On</strong>e can fur<strong>the</strong>r<br />

constra<strong>in</strong> <strong>the</strong> parameter space by <strong>the</strong> condition that all masses are positive, and that<br />

<strong>the</strong> vacuum value of <strong>the</strong> potential signals a local m<strong>in</strong>imum, V (vℓ, vu, vd) > V (0, 0, 0)<br />

[243].

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