Changes between Version 6 and Version 7 of Octet_tcgg


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Timestamp:
Nov 3, 2015 11:22:06 PM (2 years ago)
Author:
druekeel
Comment:

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  • Octet_tcgg

    v6 v7  
    1 = A Coloron Model =
     1= A Coloron Model with a Decay to a Single Top Quark =
     2
     3This model introduces a heavy scalar color octet, the coloron. It is produced through gluon fusion and decays to a top quark and a charm quark.
    24
    35== Corresponding Authors ==
     
    1719== Description of the Model ==
    1820
    19 The
    20 {{{
    21 #!latex
    22 $SU(3)_1 \times SU(3)_2 \to SU(3)_C$
    23 }}}
    24 breaking induced by the expectation value of the
    25 {{{
    26 #!latex
    27 ({$\bf 3,\bar{ 3}$})
    28 }}}
    29 scalar field Phi generates color-octet and color-singlet scalars. The most general renormalizable potential for Phi is:
    30 {{{
    31 #!latex
    32 $V(\Phi)=-m^2_{\Phi}\text{Tr}(\Phi\Phi^\dagger) -\mu (\text{det }\Phi+\text{H.c.})+\frac{\xi}{2}\left[ \text{Tr}(\Phi\Phi^\dagger) \right]^2+\frac{k}{2}\text{Tr}(\Phi\Phi^\dagger\Phi\Phi^\dagger) \ ,$
    33 }}}
    34 where
    35 {{{
    36 #!latex
    37 $\text{det } \Phi = \frac{1}{6}\epsilon^{ijk}\epsilon^{i'j'k'}\Phi_{ii'}\Phi_{jj'}\Phi_{kk'} \ ,$
    38 }}}
    39 and where, without loss of generality, one can choose mu > 0. Assuming
    40 {{{
    41 #!latex
    42 $m^2_\Phi >0$,
    43 }}}
    44 Phi acquires a (positive) diagonal expectation value:
    45 {{{
    46 #!latex
    47 $\langle \Phi \rangle = u \cdot \mathcal{I} \,.$
    48 }}}
    49 The Phi expansion around the vacuum gives:
    50 {{{
    51 #!latex
    52 $\Phi=u+\frac{1}{\sqrt{6}}\left(\phi_R+i\phi_I\right)+\left(G^a_H+iG^a_G\right)T^a \ ,$
    53 }}}
    54 where
    55 {{{
    56 #!latex
    57 $\phi_R$, $\phi_I$
    58 }}}
    59 are singlets under SU(3)_C Additionally,
    60 {{{
    61 #!latex
    62 $G^a_G$, $a=1,\dots,8$,
    63 }}}
    64 are the Nambu-Goldstone bosons associated with the color-symmetry breaking, and
    65 {{{
    66 #!latex
    67 $G^a_H$
    68 }}}
    69 are color octets.
    70 
    71 GH can be produced in pairs through its interactions with gluons:
    72 {{{
    73 #!latex
    74 $\frac{g^2_s}{2}f^{abc}f^{ade}G^b_{\mu}G^{\mu d}G^c_H G^e_H +g_s f^{abc} G^a_{\mu} G^b_H \partial^{\mu} G^c_H \ ,$
    75 }}}
    76 or it can be produced singly via gluon-gluon fusion. This occurs at one-loop order through the cubic interaction
    77 {{{
    78 #!latex
    79 $\frac{\mu}{6} d_{abc} G^a_H G^b_H G^c_H   \,,$
    80 }}}
    81 which arises from the
    82 {{{
    83 #!latex
    84 $\mu(\det\Phi+\text{H.c.})$
    85 }}}
    86 term in the potential; where
    87 {{{
    88 #!latex
    89 $d_{abc}$
    90 }}}
    91 is the SU(3) totally symmetric tensor. The single production of GH can be described by the effective coupling
     21The color octet (GH) is a neutral heavy hadronic resonance. The Feynman diagram for the production of GH and its decay to a single top quark and a charm quark is shown below.
     22[[Image(Coloron.png)]]
     23The single production of GH can be described by the effective coupling
    9224{{{
    9325#!latex
     
    11850values that give a 50% GH decay into tc and 50% into gg. GH is a very narrow resonance, with a width of the order of 10^-4 GeV.
    11951
    120 Various Feynman Diagrams for GH processes discussed in [http://arxiv.org/abs/1409.7607v2 1409.7607v2] are shown below:
    121 
    122 [[Image(Coloron.png)]]
    123 
    124 [[Image(Colorong.png)]] [[Image(Colorong2.png)]]
    125 
    126 [[Image(ColoronDouble1.png)]] [[Image(ColoronDouble2.png)]]
    127  
    12852See more details in
    12953
     
    14468p p > GH, GH > b~ c l- vl~ @2 GHT=1 QED=2
    14569}}}
    146 To generate the settings for a specific coloron mass, use the appropriate model directory contained in the Octet-tcgg zip file.
     70To generate the settings for a specific coloron mass, use the appropriate model directory contained in the Octet-tcgg zip file. Parameter card files are included for the combination of settings that gives a branching ratio of 0.5 to tc. For other BR values, please see [http://arxiv.org/abs/1409.7607v2 1409.7607v2].
     71
     72
     73
     74== Related Models ==
     75
     76* [wiki:kkg_FV kkg_FV]
     77* [wiki:modcolorS_trip modcolorS_trip]
     78* [wiki:Wprime W-prime]