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<title>Compositeness Processes</title>
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<h2>Compositeness Processes</h2>
Compositeness scenarios may give rise to sharp resonances of excited
quarks and leptons. An excited copy of the first generation is
implemented, consisting of spin 1/2 particles. The possibility of
contact interactions between SM fermions is also implemented in the
context of <i>2 → 2</i> quark or fermion-lepton scattering.
<p/>
Related to excited fermions, the current implementation contains gauge
interaction production by quark-gluon fusion or lepton-photon fusion
and contact interaction production by quark-quark or quark-antiquark
scattering. For both the <i>2 → 1</i> and <i>2 → 2</i> processes
a non-trivial angular dependence is included in the decay, however,
only decays into gauge bosons are supported, i.e. not decays through
contact interactions. In additions to the compositeness scale and couplings
listed below, you are expected to change the excited-fermion masses in
accordance with what is desired. See [<a href="Bibliography.html" target="page">Bau90</a>] for conventions.
<p/>
The contact interactions are implemented according to [<a href="Bibliography.html" target="page">Eic83</a>].
The processes include the SM contributions as well as interference.
For this reason the processes below converge toward the SM equivalents
when the contact interaction contributions are close to zero, e.g.
<code>HardQCD:qq2qq</code> and <code>HardQCD:qqbar2qqbarNew</code> in
the case of quark scattering.
<h3>Excited fermions, production processes</h3>
A few different production processes have been implemented, which normally
would not overlap and therefore could be run together.
<p/><code>flag </code><strong> ExcitedFermion:all </strong>
(<code>default = <strong>off</strong></code>)<br/>
Common switch for the group of implemented processes that produce an
excited fermion.
<p/><code>flag </code><strong> ExcitedFermion:dg2dStar </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>d g → d^*</i>.
Code 4001.
<p/><code>flag </code><strong> ExcitedFermion:ug2uStar </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>u g → u^*</i>.
Code 4002.
<p/><code>flag </code><strong> ExcitedFermion:sg2sStar </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>s g → s^*</i>.
Code 4003.
<p/><code>flag </code><strong> ExcitedFermion:cg2cStar </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>c g → c^*</i>.
Code 4004.
<p/><code>flag </code><strong> ExcitedFermion:bg2bStar </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>b g → b^*</i>.
Code 4005.
<p/><code>flag </code><strong> ExcitedFermion:egm2eStar </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>e gamma → e^*</i>.
Code 4011.
<p/><code>flag </code><strong> ExcitedFermion:mugm2muStar </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>mu gamma → mu^*</i>.
Code 4013.
<p/><code>flag </code><strong> ExcitedFermion:taugm2tauStar </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>tau gamma → tau^*</i>.
Code 4015.
<p/><code>flag </code><strong> ExcitedFermion:qq2dStarq </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>q q(bar) → d^* q(bar)</i>.
Code 4021.
<p/><code>flag </code><strong> ExcitedFermion:qq2uStarq </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>q q(bar) → u^* q(bar)</i>.
Code 4022.
<p/><code>flag </code><strong> ExcitedFermion:qq2sStarq </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>q q(bar) → s^* q(bar)</i>.
Code 4023.
<p/><code>flag </code><strong> ExcitedFermion:qq2cStarq </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>q q(bar) → c^* q(bar)</i>.
Code 4024.
<p/><code>flag </code><strong> ExcitedFermion:qq2bStarq </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>q q(bar) → b^* q(bar)</i>.
Code 4025.
<p/><code>flag </code><strong> ExcitedFermion:qqbar2eStare </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>q qbar → e^*+- e^-+</i>.
Code 4031.
<p/><code>flag </code><strong> ExcitedFermion:qqbar2nueStarnue </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>q qbar → nu_e^* nu_ebar</i>.
Code 4032.
<p/><code>flag </code><strong> ExcitedFermion:qqbar2muStarmu </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>q qbar → mu^*+- mu^-+</i>.
Code 4033.
<p/><code>flag </code><strong> ExcitedFermion:qqbar2numuStarnumu </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>q qbar → nu_mu^* nu_mubar</i>.
Code 4034.
<p/><code>flag </code><strong> ExcitedFermion:qqbar2tauStartau </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>q qbar → tau^*+- tau^-+</i>.
Code 4035.
<p/><code>flag </code><strong> ExcitedFermion:qqbar2nutauStarnutau </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>q qbar → nu_tau^* nu_taubar</i>.
Code 4036.
<h3>Excited fermions, parameters</h3>
The basic couplings of the model are
<p/><code>parm </code><strong> ExcitedFermion:Lambda </strong>
(<code>default = <strong>1000.</strong></code>; <code>minimum = 100.</code>)<br/>
Compositeness scale <i>Lambda</i> in GeV.
<p/><code>parm </code><strong> ExcitedFermion:coupF </strong>
(<code>default = <strong>1.0</strong></code>; <code>minimum = 0.0</code>)<br/>
Strength <i>f</i> of the <i>SU(2)</i> coupling.
<p/><code>parm </code><strong> ExcitedFermion:coupFprime </strong>
(<code>default = <strong>1.0</strong></code>; <code>minimum = 0.0</code>)<br/>
Strength <i>f'</i> of the <i>U(1)</i> coupling.
<p/><code>parm </code><strong> ExcitedFermion:coupFcol </strong>
(<code>default = <strong>1.0</strong></code>; <code>minimum = 0.0</code>)<br/>
Strength <i>f_c</i> of the <i>SU(3)</i> coupling.
<h3>Contact interactions, production processes</h3>
The processes including contact interactions are
<p/><code>flag </code><strong> ContactInteractions:QCqq2qq </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>q q → q q</i> including contact interactions.
Code 4201.
<p/><code>flag </code><strong> ContactInteractions:QCqqbar2qqbar </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>q qbar → q' qbar'</i> including contact interactions.
Code 4202.
<p/><code>flag </code><strong> ContactInteractions:QCffbar2eebar </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>f fbar → e- e+</i> including contact interactions.
Code 4203.
<p/><code>flag </code><strong> ContactInteractions:QCffbar2mumubar </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>f fbar → mu- mu+</i> including contact interactions.
Code 4204.
<p/><code>flag </code><strong> ContactInteractions:QCffbar2tautaubar </strong>
(<code>default = <strong>off</strong></code>)<br/>
Scatterings <i>f fbar → tau- tau+</i> including contact interactions.
Code 4205.
<h3>Contact interactions, parameters</h3>
<p/><code>mode </code><strong> ContactInteractions:nQuarkNew </strong>
(<code>default = <strong>3</strong></code>; <code>minimum = 0</code>; <code>maximum = 5</code>)<br/>
Number of allowed outgoing new quark flavours in the above
<i>q qbar → q' qbar'</i> process. Similar to <i>HardQCD:nQuarkNew</i>
for the QCD processes.
<p/><code>parm </code><strong> ContactInteractions:Lambda </strong>
(<code>default = <strong>1000.</strong></code>; <code>minimum = 100.</code>)<br/>
Compositeness scale <i>Lambda</i> in GeV. Its overall normalization
is largely a matter of convention. The choice made here for the
<i>q qbar → l- l+</i> processes is such that the pure contact
interaction part of the left-left interactions (i.e. disregarding
<i>gamma^*</i>, <i>Z^0</i> and interference terms) has the form
<i>d(sigmaHat)/d(tHat) = pi * uHat^2 / (3 * sHat^2 * Lambda^4)</i>.
The corresponding part of the <i>q qbar → q' qbar'</i> cross section
is a factor 3 larger from colour.
<p/><code>mode </code><strong> ContactInteractions:etaLL </strong>
(<code>default = <strong>0</strong></code>; <code>minimum = -1</code>; <code>maximum = 1</code>)<br/>
Helicity parameter.
<br/><code>option </code><strong> 1</strong> :
<br/><code>option </code><strong> 0</strong> :
<br/><code>option </code><strong> -1</strong> :
<p/><code>mode </code><strong> ContactInteractions:etaRR </strong>
(<code>default = <strong>0</strong></code>; <code>minimum = -1</code>; <code>maximum = 1</code>)<br/>
Helicity parameter.
<br/><code>option </code><strong> 1</strong> :
<br/><code>option </code><strong> 0</strong> :
<br/><code>option </code><strong> -1</strong> :
<p/><code>mode </code><strong> ContactInteractions:etaLR </strong>
(<code>default = <strong>0</strong></code>; <code>minimum = -1</code>; <code>maximum = 1</code>)<br/>
Helicity parameter.
<br/><code>option </code><strong> 1</strong> :
<br/><code>option </code><strong> 0</strong> :
<br/><code>option </code><strong> -1</strong> :
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