wiki:Octet_tcgg

Version 2 (modified by druekeel, 2 years ago) (diff)

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A Coloron Model

Authors

  • Elizabeth Drueke (Michigan State University)
  • Joseph Nutter (Michigan State University)
  • Reinhard Schwienhorst (Michigan State University)
  • Natascia Vignaroli (Michigan State University)
  • Devin G. E. Walker (SLAC National Accelerator Laboratory)
  • Jiang-Hao Yu (The University of Texas at Austin)

Description of the Model

Colored vector bosons from new strong dynamics, Kaluza-Klein gluons or KKg’s (G*) in a dual 5D picture, have been searched for mainly in the t-tbar channel. In this model, the third generation quarks couple differently than the light quarks under an extended

$SU(3)_1 \times SU(3)_2$

color gauge group. The mixing between light and third generation quarks is induced by the interactions of all three generation quarks with a set of new heavy vector0like quarks. The model reproduces the CKM mixing and generates flavor-changing neutral currents (FCNCs) from non-standard interactions. Due to the specific structure of the model, dangerous FCNCs are naturally suppressed and a large portion of the model parameter space is allowed by the data on meson mixing process and on

$b \to \gamma$.

The extended color symmetry is broken down to

$SU(3)_C$

by the (diagonal) expectation value,

$\langle \Phi \rangle \propto u \cdot {\cal I}$,

of a scalar field Phi which transforms as a

$\bf 3, \bar{3}$

under the color gauge structure. It is assumed that color gauge breaking occurs at a scale much higher than the electroweak scale.

Breaking the color symmetry induces a mixing between the

$SU(3)_1$ \rm{and} $SU(3)_2$

gauge fields

$A^{1}_{\mu}$ \rm{and} $A^{2}_{\mu}$,

which is diagonalized by a rotation determined by

$\cot\omega = \frac{g_1}{g_2} \qquad g_s = g_1 \sin\omega = g_2 \cos\omega$,

where g_s is the QCD strong coupling and g_1 and g_2 are the SU(3)_1 and SU(3)_2 gauge couplings, respectively. The mixing diagonalization reveals two color vector boson mass eigenstates: the mass-less SM gluon and a new massive color-octet vector boson G* given by

$G^{*}_{\mu}=\cos\omega A^{1}_{\mu} - \sin\omega A^{2}_{\mu} \qquad M_{G^{*}} = \frac{g_s u}{\sin\omega \cos\omega}.$

In the NMFV model, the third generation quarks couple differently than the light quarks under the extended color group.

$g_L=(t_L, b_L),$ \rm{ } $t_R,$ \rm{ and } $b_R,$

as well as a new weak-doublet of vector-like quarks, transform as

$({\bf 3,1})$

under the color gauge group, while the light generation quarks are charged under SU(3)_2 and transform as

$({\bf 1,3})$

The G* interactions with the color currents associated with SU(3)_1 and SU(3)_2 are given by

$g_s \left(\cot\omega J^{\mu}_1 - \tan\omega J^{\mu}_2 \right)G^{*}_{\mu}.$

Note

Need to reread and make sure everything is the same as the paper and that nothing for KKg has been carried over.

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