<chapter name="Compositeness Processes">
<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 <ei>2 → 2</ei> 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 <ei>2 → 1</ei> and <ei>2 → 2</ei> 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 <ref>Bau90</ref> for conventions.
<p/>
The contact interactions are implemented according to <ref>Eic83</ref>.
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.
<flag name="ExcitedFermion:all" default="off">
Common switch for the group of implemented processes that produce an
excited fermion.
</flag>
<flag name="ExcitedFermion:dg2dStar" default="off">
Scatterings <ei>d g → d^*</ei>.
Code 4001.
</flag>
<flag name="ExcitedFermion:ug2uStar" default="off">
Scatterings <ei>u g → u^*</ei>.
Code 4002.
</flag>
<flag name="ExcitedFermion:sg2sStar" default="off">
Scatterings <ei>s g → s^*</ei>.
Code 4003.
</flag>
<flag name="ExcitedFermion:cg2cStar" default="off">
Scatterings <ei>c g → c^*</ei>.
Code 4004.
</flag>
<flag name="ExcitedFermion:bg2bStar" default="off">
Scatterings <ei>b g → b^*</ei>.
Code 4005.
</flag>
<flag name="ExcitedFermion:egm2eStar" default="off">
Scatterings <ei>e gamma → e^*</ei>.
Code 4011.
</flag>
<flag name="ExcitedFermion:mugm2muStar" default="off">
Scatterings <ei>mu gamma → mu^*</ei>.
Code 4013.
</flag>
<flag name="ExcitedFermion:taugm2tauStar" default="off">
Scatterings <ei>tau gamma → tau^*</ei>.
Code 4015.
</flag>
<flag name="ExcitedFermion:qq2dStarq" default="off">
Scatterings <ei>q q(bar) → d^* q(bar)</ei>.
Code 4021.
</flag>
<flag name="ExcitedFermion:qq2uStarq" default="off">
Scatterings <ei>q q(bar) → u^* q(bar)</ei>.
Code 4022.
</flag>
<flag name="ExcitedFermion:qq2sStarq" default="off">
Scatterings <ei>q q(bar) → s^* q(bar)</ei>.
Code 4023.
</flag>
<flag name="ExcitedFermion:qq2cStarq" default="off">
Scatterings <ei>q q(bar) → c^* q(bar)</ei>.
Code 4024.
</flag>
<flag name="ExcitedFermion:qq2bStarq" default="off">
Scatterings <ei>q q(bar) → b^* q(bar)</ei>.
Code 4025.
</flag>
<flag name="ExcitedFermion:qqbar2eStare" default="off">
Scatterings <ei>q qbar → e^*+- e^-+</ei>.
Code 4031.
</flag>
<flag name="ExcitedFermion:qqbar2nueStarnue" default="off">
Scatterings <ei>q qbar → nu_e^* nu_ebar</ei>.
Code 4032.
</flag>
<flag name="ExcitedFermion:qqbar2muStarmu" default="off">
Scatterings <ei>q qbar → mu^*+- mu^-+</ei>.
Code 4033.
</flag>
<flag name="ExcitedFermion:qqbar2numuStarnumu" default="off">
Scatterings <ei>q qbar → nu_mu^* nu_mubar</ei>.
Code 4034.
</flag>
<flag name="ExcitedFermion:qqbar2tauStartau" default="off">
Scatterings <ei>q qbar → tau^*+- tau^-+</ei>.
Code 4035.
</flag>
<flag name="ExcitedFermion:qqbar2nutauStarnutau" default="off">
Scatterings <ei>q qbar → nu_tau^* nu_taubar</ei>.
Code 4036.
</flag>
<h3>Excited fermions, parameters</h3>
The basic couplings of the model are
<parm name="ExcitedFermion:Lambda" default="1000." min="100.">
Compositeness scale <ei>Lambda</ei> in GeV.
</parm>
<parm name="ExcitedFermion:coupF" default="1.0" min="0.0">
Strength <ei>f</ei> of the <ei>SU(2)</ei> coupling.
</parm>
<parm name="ExcitedFermion:coupFprime" default="1.0" min="0.0">
Strength <ei>f'</ei> of the <ei>U(1)</ei> coupling.
</parm>
<parm name="ExcitedFermion:coupFcol" default="1.0" min="0.0">
Strength <ei>f_c</ei> of the <ei>SU(3)</ei> coupling.
</parm>
<h3>Contact interactions, production processes</h3>
The processes including contact interactions are
<flag name="ContactInteractions:QCqq2qq" default="off">
Scatterings <ei>q q → q q</ei> including contact interactions.
Code 4201.
</flag>
<flag name="ContactInteractions:QCqqbar2qqbar" default="off">
Scatterings <ei>q qbar → q' qbar'</ei> including contact interactions.
Code 4202.
</flag>
<flag name="ContactInteractions:QCffbar2eebar" default="off">
Scatterings <ei>f fbar → e- e+</ei> including contact interactions.
Code 4203.
</flag>
<flag name="ContactInteractions:QCffbar2mumubar" default="off">
Scatterings <ei>f fbar → mu- mu+</ei> including contact interactions.
Code 4204.
</flag>
<flag name="ContactInteractions:QCffbar2tautaubar" default="off">
Scatterings <ei>f fbar → tau- tau+</ei> including contact interactions.
Code 4205.
</flag>
<h3>Contact interactions, parameters</h3>
<modeopen name="ContactInteractions:nQuarkNew" default="3" min="0" max="5">
Number of allowed outgoing new quark flavours in the above
<ei>q qbar → q' qbar'</ei> process. Similar to <ei>HardQCD:nQuarkNew</ei>
for the QCD processes.
</modeopen>
<parm name="ContactInteractions:Lambda" default="1000." min="100.">
Compositeness scale <ei>Lambda</ei> in GeV. Its overall normalization
is largely a matter of convention. The choice made here for the
<ei>q qbar → l- l+</ei> processes is such that the pure contact
interaction part of the left-left interactions (i.e. disregarding
<ei>gamma^*</ei>, <ei>Z^0</ei> and interference terms) has the form
<ei>d(sigmaHat)/d(tHat) = pi * uHat^2 / (3 * sHat^2 * Lambda^4)</ei>.
The corresponding part of the <ei>q qbar → q' qbar'</ei> cross section
is a factor 3 larger from colour.
</parm>
<modepick name="ContactInteractions:etaLL" default="0" min="-1" max="1">
Helicity parameter.
<option value="1"></option>
<option value="0"></option>
<option value="-1"></option>
</modepick>
<modepick name="ContactInteractions:etaRR" default="0" min="-1" max="1">
Helicity parameter.
<option value="1"></option>
<option value="0"></option>
<option value="-1"></option>
</modepick>
<modepick name="ContactInteractions:etaLR" default="0" min="-1" max="1">
Helicity parameter.
<option value="1"></option>
<option value="0"></option>
<option value="-1"></option>
</modepick>
</chapter>
<!-- Copyright (C) 2014 Torbjorn Sjostrand -->
Marcin Chrzaszcz