# Changes between Version 7 and Version 8 of kkg_FV

Ignore:
Timestamp:
11/03/15 23:22:10 (4 years ago)
Comment:

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Unmodified
 v7 = A Kaluza-Klein Gluon Model = = A Kaluza-Klein Gluon Model with FCNC Decay to a Single Top Quark = This model allows for FCNC interactions of the Kaluza-Klein gluon and in particular focuses on the flavor-violating decay of the KKg to a top quark and a charm quark. == Corresponding Authors == $SU(3)_1 \times SU(3)_2$ }}} 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 vector-like 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 {{{ #!latex $b \to s\gamma$. }}} The model has the color gauge structure {{{ #!latex $SU(3)_1 \times SU(3)_2$ }}} The extended color symmetry is broken down to {{{ #!latex $SU(3)_C$ }}} by the (diagonal) expectation value, {{{ #!latex $\langle \Phi \rangle \propto u \cdot {\cal I}$, }}} of a scalar field Phi which transforms as a {{{ #!latex $(\bf 3, \bar{3})$ }}} under the color gauge structure.  It is assumed that color gauge breaking occurs at a scale much higher than the electroweak scale, u>>v. Breaking the color symmetry induces a mixing between the {{{ #!latex $SU(3)_1$ \rm{and} $SU(3)_2$ }}} gauge fields {{{ #!latex $A^{1}_{\mu}$ \rm{and} $A^{2}_{\mu}$, }}} which is diagonalized by a rotation determined by {{{ #!latex $\cot\omega = \frac{g_1}{g_2} \qquad g_s = g_1 \sin\omega = g_2 \cos\omega$, }}} where g_s is the QCD strong coupling and g_1, 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 {{{ #!latex $G^{*}_{\mu}=\cos\omega A^{1}_{\mu} - \sin\omega A^{2}_{\mu} \qquad M_{G^{*}} = \frac{g_s u}{\sin\omega \cos\omega}.$ }}} In the NMFV model, the third generation quarks couple differently than the light quarks under the extended color group. {{{ #!latex $g_L=(t_L, b_L),$ \rm{ } $t_R,$ \rm{ and } $b_R,$ }}} as well as a new weak-doublet of vector-like quarks, transform as {{{ #!latex $({\bf 3,1})$ }}} under the color gauge group, while the light generation quarks are charged under SU(3)_2 and transform as {{{ #!latex $({\bf 1,3})$ }}} The G* interactions with the color currents associated with SU(3)_1 and SU(3)_2 are given by {{{ #!latex $g_s \left(\cot\omega J^{\mu}_1 - \tan\omega J^{\mu}_2 \right)G^{*}_{\mu}.$ }}} The G* can be produced at the LHC by quark-antiquark fusion determined by the G* coupling to light quarks {{{ #!latex $g_s \tan\omega$ }}} Gluon-gluon fusion production is forbidden at tree level by SU(3)_C gauge invariance. 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 vector-like quarks. Gluon-gluon fusion production is forbidden at tree level by SU(3)_C gauge invariance. The G* decay widths are: $V_{cb}=0.0415$ }}} is the CKM matrix element. Note here that G* FCNCs are induced by the mixing among left-handed quarks generated by the exchange of heavy vector-like quarks. This mixing is controlled by the 3x3 matrices U_L and D_L in the up- and down-quark sectors, respectively. In particular, the is the CKM matrix element. Throughout this discussion, it is important to note that {{{ #!latex $G* \to tc$ }}} flavor violating decay is controlled by the {{{ #!latex $(U_L)_{23}$ }}} element. The CKM mixing matrix is given by {{{ #!latex $V_{CKM}=U^{\dagger}_L D_L$. }}} At first order in the mixing parameters, {{{ #!latex $(U_L)_{23}\equiv V_{cb} - (D_L)_{23}$. }}} The non-diagonal elements of D_L are strongly constrained by the data on {{{ #!latex $b\to s \gamma$. }}} So {{{ #!latex $(D_L)_{23}$ }}} is thus forced to be small and, as a consequence, {{{ #!latex $(U_L)_{23}\simeq V_{cb}$. $ct\eta \neq \omega$ }}} See more details in }}} To generate the settings for a specific KKg mass, param_card.dat in the generation directory to the card of the appropriate mass in the param_cards directory (included as part of the model zip file). == Related Models == * [wiki:modcolorS_trip modcolorS_trip] * [wiki:Octet_tcgg Octet_tcgg] * [wiki:Wprime W-prime]