Changes between Version 7 and Version 8 of kkg_FV


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Timestamp:
Nov 3, 2015 11:22:10 PM (3 years ago)
Author:
druekeel
Comment:

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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]