Changes between Version 7 and Version 8 of kkg_FV


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Timestamp:
11/03/15 23:22:10 (19 months ago)
Author:
druekeel
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  • kkg_FV

    v7 v8  
    1 = A Kaluza-Klein Gluon Model = 
     1= A Kaluza-Klein Gluon Model with FCNC Decay to a Single Top Quark = 
     2 
     3This 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. 
    24 
    35== Corresponding Authors == 
     
    2527$SU(3)_1 \times SU(3)_2$ 
    2628}}} 
    27 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  
    28 {{{ 
    29 #!latex 
    30 $b \to s\gamma$. 
    31 }}} 
    32 The model has the color gauge structure 
    33 {{{ 
    34 #!latex 
    35 $SU(3)_1 \times SU(3)_2$ 
    36 }}} 
    37 The extended color symmetry is broken down to  
    38 {{{ 
    39 #!latex 
    40 $SU(3)_C$ 
    41 }}} 
    42 by the (diagonal) expectation value, 
    43 {{{ 
    44 #!latex 
    45 $\langle \Phi \rangle \propto u \cdot {\cal I}$, 
    46 }}} 
    47 of a scalar field Phi which transforms as a  
    48 {{{ 
    49 #!latex 
    50 $(\bf 3, \bar{3})$ 
    51 }}} 
    52 under the color gauge structure.  It is assumed that color gauge breaking occurs at a scale much higher than the electroweak scale, u>>v. 
    53  
    54 Breaking the color symmetry induces a mixing between the  
    55 {{{ 
    56 #!latex 
    57 $SU(3)_1$ \rm{and} $SU(3)_2$ 
    58 }}} 
    59 gauge fields 
    60 {{{ 
    61 #!latex 
    62 $A^{1}_{\mu}$ \rm{and} $A^{2}_{\mu}$, 
    63 }}} 
    64 which is diagonalized by a rotation determined by  
    65 {{{ 
    66 #!latex 
    67 $\cot\omega = \frac{g_1}{g_2} \qquad g_s = g_1 \sin\omega = g_2 \cos\omega$, 
    68 }}} 
    69 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 
    70 {{{ 
    71 #!latex 
    72 $G^{*}_{\mu}=\cos\omega A^{1}_{\mu} - \sin\omega A^{2}_{\mu} \qquad M_{G^{*}} = \frac{g_s u}{\sin\omega \cos\omega}.$ 
    73 }}} 
    74 In the NMFV model, the third generation quarks couple differently than the light quarks under the extended color group.   
    75 {{{ 
    76 #!latex 
    77 $g_L=(t_L, b_L),$ \rm{ } $t_R,$ \rm{ and } $b_R,$ 
    78 }}} 
    79 as well as a new weak-doublet of vector-like quarks, transform as  
    80 {{{ 
    81 #!latex 
    82 $({\bf 3,1})$ 
    83 }}} 
    84 under the color gauge group, while the light generation quarks are charged under SU(3)_2 and transform as 
    85 {{{ 
    86 #!latex 
    87 $({\bf 1,3})$ 
    88 }}} 
    89 The G* interactions with the color currents associated with SU(3)_1 and SU(3)_2 are given by 
    90 {{{ 
    91 #!latex 
    92 $g_s \left(\cot\omega J^{\mu}_1 - \tan\omega J^{\mu}_2 \right)G^{*}_{\mu}.$ 
    93 }}} 
    94  
    95  
    96 The G* can be produced at the LHC by quark-antiquark fusion determined by the G* coupling to light quarks  
    97 {{{ 
    98 #!latex 
    99 $g_s \tan\omega$ 
    100 }}} 
    101 Gluon-gluon fusion production is forbidden at tree level by SU(3)_C gauge invariance.  
     29color 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.  
    10230 
    10331The G* decay widths are: 
     
    11846$V_{cb}=0.0415$ 
    11947}}} 
    120 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  
     48is the CKM matrix element. Throughout this discussion, it is important to note that  
    12149{{{ 
    12250#!latex 
    123 $G* \to tc$ 
    124 }}} 
    125 flavor violating decay is controlled by the  
    126 {{{ 
    127 #!latex 
    128 $(U_L)_{23}$ 
    129 }}} 
    130 element. The CKM mixing matrix is given by  
    131 {{{ 
    132 #!latex 
    133 $V_{CKM}=U^{\dagger}_L D_L$. 
    134 }}} 
    135 At first order in the mixing parameters,  
    136 {{{ 
    137 #!latex 
    138 $(U_L)_{23}\equiv V_{cb} - (D_L)_{23}$. 
    139 }}} 
    140 The non-diagonal elements of D_L are strongly constrained by the data on  
    141 {{{ 
    142 #!latex 
    143 $b\to s \gamma$.  
    144 }}} 
    145 So 
    146 {{{ 
    147 #!latex 
    148 $(D_L)_{23}$ 
    149 }}} 
    150 is thus forced to be small and, as a consequence,  
    151 {{{ 
    152 #!latex 
    153 $(U_L)_{23}\simeq V_{cb}$. 
     51$ct\eta \neq \omega$ 
    15452}}} 
    15553See more details in 
     
    17169}}} 
    17270To 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). 
     71 
     72== Related Models == 
     73 
     74* [wiki:modcolorS_trip modcolorS_trip] 
     75* [wiki:Octet_tcgg Octet_tcgg] 
     76* [wiki:Wprime W-prime]