3 <title>Compositeness Processes</title>
4 <link rel="stylesheet" type="text/css" href="pythia.css"/>
5 <link rel="shortcut icon" href="pythia32.gif"/>
9 <h2>Compositeness Processes</h2>
11 Compositeness scenarios may give rise to sharp resonances of excited
12 quarks and leptons. An excited copy of the first generation is
13 implemented, consisting of spin 1/2 particles. The possibility of
14 contact interactions between quarks is also implemented in the context
15 of <i>2 -> 2</i> quark scattering.
18 Related to excited fermions, the current implementation contains gauge
19 interaction production by quark-gluon fusion or lepton-photon fusion
20 and contact interaction production by quark-quark or quark-antiquark
21 scattering. In additions to the compositness scale and couplings listed
22 below, you are expected to change the excited-fermion masses in accordance
23 with what is desired. See [<a href="Bibliography.html" target="page">Bau90</a>] for conventions.
26 A non-trivial angular dependence is included in the decay for the
27 <i>2 -> 1</i> processes, but has not been included for the
31 The quark contact interactions are implemented according to
32 [<a href="Bibliography.html" target="page">Eic83</a>]. The processes include the QCD contributions
33 as well as interference. For this reason the two processes
34 below converge toward, <code>HardQCD:qq2qq</code> and
35 <code>HardQCD:qqbar2qqbarNew</code>, when the contact interaction
36 contributions are close to zero.
38 <h3>Excited fermions, production processes</h3>
40 A few different production processes have been implemented, which normally
41 would not overlap and therefore could be run together.
43 <p/><code>flag </code><strong> ExcitedFermion:all </strong>
44 (<code>default = <strong>off</strong></code>)<br/>
45 Common switch for the group of implemented processes that produce an
49 <p/><code>flag </code><strong> ExcitedFermion:dg2dStar </strong>
50 (<code>default = <strong>off</strong></code>)<br/>
51 Scatterings <i>d g -> d^*</i>.
55 <p/><code>flag </code><strong> ExcitedFermion:ug2uStar </strong>
56 (<code>default = <strong>off</strong></code>)<br/>
57 Scatterings <i>u g -> u^*</i>.
61 <p/><code>flag </code><strong> ExcitedFermion:sg2sStar </strong>
62 (<code>default = <strong>off</strong></code>)<br/>
63 Scatterings <i>s g -> s^*</i>.
67 <p/><code>flag </code><strong> ExcitedFermion:cg2cStar </strong>
68 (<code>default = <strong>off</strong></code>)<br/>
69 Scatterings <i>c g -> c^*</i>.
73 <p/><code>flag </code><strong> ExcitedFermion:bg2bStar </strong>
74 (<code>default = <strong>off</strong></code>)<br/>
75 Scatterings <i>b g -> b^*</i>.
79 <p/><code>flag </code><strong> ExcitedFermion:egm2eStar </strong>
80 (<code>default = <strong>off</strong></code>)<br/>
81 Scatterings <i>e gamma -> e^*</i>.
85 <p/><code>flag </code><strong> ExcitedFermion:mugm2muStar </strong>
86 (<code>default = <strong>off</strong></code>)<br/>
87 Scatterings <i>mu gamma -> mu^*</i>.
91 <p/><code>flag </code><strong> ExcitedFermion:taugm2tauStar </strong>
92 (<code>default = <strong>off</strong></code>)<br/>
93 Scatterings <i>tau gamma -> tau^*</i>.
97 <p/><code>flag </code><strong> ExcitedFermion:qq2dStarq </strong>
98 (<code>default = <strong>off</strong></code>)<br/>
99 Scatterings <i>q q(bar) -> d^* q(bar)</i>.
103 <p/><code>flag </code><strong> ExcitedFermion:qq2uStarq </strong>
104 (<code>default = <strong>off</strong></code>)<br/>
105 Scatterings <i>q q(bar) -> u^* q(bar)</i>.
109 <p/><code>flag </code><strong> ExcitedFermion:qq2sStarq </strong>
110 (<code>default = <strong>off</strong></code>)<br/>
111 Scatterings <i>q q(bar) -> s^* q(bar)</i>.
115 <p/><code>flag </code><strong> ExcitedFermion:qq2cStarq </strong>
116 (<code>default = <strong>off</strong></code>)<br/>
117 Scatterings <i>q q(bar) -> c^* q(bar)</i>.
121 <p/><code>flag </code><strong> ExcitedFermion:qq2bStarq </strong>
122 (<code>default = <strong>off</strong></code>)<br/>
123 Scatterings <i>q q(bar) -> b^* q(bar)</i>.
127 <p/><code>flag </code><strong> ExcitedFermion:qqbar2eStare </strong>
128 (<code>default = <strong>off</strong></code>)<br/>
129 Scatterings <i>q qbar -> e^*+- e^-+</i>.
133 <p/><code>flag </code><strong> ExcitedFermion:qqbar2nueStarnue </strong>
134 (<code>default = <strong>off</strong></code>)<br/>
135 Scatterings <i>q qbar -> nu_e^* nu_ebar</i>.
139 <p/><code>flag </code><strong> ExcitedFermion:qqbar2muStarmu </strong>
140 (<code>default = <strong>off</strong></code>)<br/>
141 Scatterings <i>q qbar -> mu^*+- mu^-+</i>.
145 <p/><code>flag </code><strong> ExcitedFermion:qqbar2numuStarnumu </strong>
146 (<code>default = <strong>off</strong></code>)<br/>
147 Scatterings <i>q qbar -> nu_mu^* nu_mubar</i>.
151 <p/><code>flag </code><strong> ExcitedFermion:qqbar2tauStartau </strong>
152 (<code>default = <strong>off</strong></code>)<br/>
153 Scatterings <i>q qbar -> tau^*+- tau^-+</i>.
157 <p/><code>flag </code><strong> ExcitedFermion:qqbar2nutauStarnutau </strong>
158 (<code>default = <strong>off</strong></code>)<br/>
159 Scatterings <i>q qbar -> nu_tau^* nu_taubar</i>.
163 <h3>Excited fermions, parameters</h3>
165 The basic couplings of the model are
167 <p/><code>parm </code><strong> ExcitedFermion:Lambda </strong>
168 (<code>default = <strong>1000.</strong></code>; <code>minimum = 100.</code>)<br/>
169 Compositeness scale <i>Lambda</i> in GeV.
172 <p/><code>parm </code><strong> ExcitedFermion:coupF </strong>
173 (<code>default = <strong>1.0</strong></code>; <code>minimum = 0.0</code>)<br/>
174 Strength <i>f</i> of the <i>SU(2)</i> coupling.
177 <p/><code>parm </code><strong> ExcitedFermion:coupFprime </strong>
178 (<code>default = <strong>1.0</strong></code>; <code>minimum = 0.0</code>)<br/>
179 Strength <i>f'</i> of the <i>U(1)</i> coupling.
182 <p/><code>parm </code><strong> ExcitedFermion:coupFcol </strong>
183 (<code>default = <strong>1.0</strong></code>; <code>minimum = 0.0</code>)<br/>
184 Strength <i>f_c</i> of the <i>SU(3)</i> coupling.
187 <h3>Contact interactions, production processes</h3>
189 The processes including quark contact interactions are
191 <p/><code>flag </code><strong> ContactInteractions:QCqq2qq </strong>
192 (<code>default = <strong>off</strong></code>)<br/>
193 Scatterings <i>q q -> q q</i> including contact interactions.
197 <p/><code>flag </code><strong> ContactInteractions:QCqqbar2qqbar </strong>
198 (<code>default = <strong>off</strong></code>)<br/>
199 Scatterings <i>q qbar -> q' qbar'</i> including contact interactions.
203 <h3>Contact interactions, parameters</h3>
205 <p/><code>mode </code><strong> ContactInteractions:nQuarkNew </strong>
206 (<code>default = <strong>3</strong></code>; <code>minimum = 0</code>; <code>maximum = 5</code>)<br/>
207 Number of allowed outgoing new quark flavours in the above
208 <i>q qbar -> q' qbar'</i> process. Similar to <i>HardQCD:nQuarkNew</i>
209 for the QCD processes.
212 <p/><code>parm </code><strong> ContactInteractions:Lambda </strong>
213 (<code>default = <strong>1000.</strong></code>; <code>minimum = 100.</code>)<br/>
214 Compositeness scale <i>Lambda</i> in GeV.
217 <p/><code>mode </code><strong> ContactInteractions:etaLL </strong>
218 (<code>default = <strong>0</strong></code>; <code>minimum = -1</code>; <code>maximum = 1</code>)<br/>
220 <br/><code>option </code><strong> 1</strong> :
221 <br/><code>option </code><strong> 0</strong> :
222 <br/><code>option </code><strong> -1</strong> :
225 <p/><code>mode </code><strong> ContactInteractions:etaRR </strong>
226 (<code>default = <strong>0</strong></code>; <code>minimum = -1</code>; <code>maximum = 1</code>)<br/>
228 <br/><code>option </code><strong> 1</strong> :
229 <br/><code>option </code><strong> 0</strong> :
230 <br/><code>option </code><strong> -1</strong> :
233 <p/><code>mode </code><strong> ContactInteractions:etaLR </strong>
234 (<code>default = <strong>0</strong></code>; <code>minimum = -1</code>; <code>maximum = 1</code>)<br/>
236 <br/><code>option </code><strong> 1</strong> :
237 <br/><code>option </code><strong> 0</strong> :
238 <br/><code>option </code><strong> -1</strong> :
244 <!-- Copyright (C) 2010 Torbjorn Sjostrand -->