Compositeness Processes

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 quarks is also implemented in the context of 2 -> 2 quark scattering.

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. In additions to the compositness scale and couplings listed below, you are expected to change the excited-fermion masses in accordance with what is desired. See [Bau90] for conventions.

A non-trivial angular dependence is included in the decay for the 2 -> 1 processes, but has not been included for the 2 -> 2 ones.

The quark contact interactions are implemented according to [Eic83]. The processes include the QCD contributions as well as interference. For this reason the two processes below converge toward, HardQCD:qq2qq and HardQCD:qqbar2qqbarNew, when the contact interaction contributions are close to zero.

Excited fermions, production processes

A few different production processes have been implemented, which normally would not overlap and therefore could be run together.

flag  ExcitedFermion:all   (default = off)
Common switch for the group of implemented processes that produce an excited fermion.

flag  ExcitedFermion:dg2dStar   (default = off)
Scatterings d g -> d^*. Code 4001.

flag  ExcitedFermion:ug2uStar   (default = off)
Scatterings u g -> u^*. Code 4002.

flag  ExcitedFermion:sg2sStar   (default = off)
Scatterings s g -> s^*. Code 4003.

flag  ExcitedFermion:cg2cStar   (default = off)
Scatterings c g -> c^*. Code 4004.

flag  ExcitedFermion:bg2bStar   (default = off)
Scatterings b g -> b^*. Code 4005.

flag  ExcitedFermion:egm2eStar   (default = off)
Scatterings e gamma -> e^*. Code 4011.

flag  ExcitedFermion:mugm2muStar   (default = off)
Scatterings mu gamma -> mu^*. Code 4013.

flag  ExcitedFermion:taugm2tauStar   (default = off)
Scatterings tau gamma -> tau^*. Code 4015.

flag  ExcitedFermion:qq2dStarq   (default = off)
Scatterings q q(bar) -> d^* q(bar). Code 4021.

flag  ExcitedFermion:qq2uStarq   (default = off)
Scatterings q q(bar) -> u^* q(bar). Code 4022.

flag  ExcitedFermion:qq2sStarq   (default = off)
Scatterings q q(bar) -> s^* q(bar). Code 4023.

flag  ExcitedFermion:qq2cStarq   (default = off)
Scatterings q q(bar) -> c^* q(bar). Code 4024.

flag  ExcitedFermion:qq2bStarq   (default = off)
Scatterings q q(bar) -> b^* q(bar). Code 4025.

flag  ExcitedFermion:qqbar2eStare   (default = off)
Scatterings q qbar -> e^*+- e^-+. Code 4031.

flag  ExcitedFermion:qqbar2nueStarnue   (default = off)
Scatterings q qbar -> nu_e^* nu_ebar. Code 4032.

flag  ExcitedFermion:qqbar2muStarmu   (default = off)
Scatterings q qbar -> mu^*+- mu^-+. Code 4033.

flag  ExcitedFermion:qqbar2numuStarnumu   (default = off)
Scatterings q qbar -> nu_mu^* nu_mubar. Code 4034.

flag  ExcitedFermion:qqbar2tauStartau   (default = off)
Scatterings q qbar -> tau^*+- tau^-+. Code 4035.

flag  ExcitedFermion:qqbar2nutauStarnutau   (default = off)
Scatterings q qbar -> nu_tau^* nu_taubar. Code 4036.

Excited fermions, parameters

The basic couplings of the model are

parm  ExcitedFermion:Lambda   (default = 1000.; minimum = 100.)
Compositeness scale Lambda in GeV.

parm  ExcitedFermion:coupF   (default = 1.0; minimum = 0.0)
Strength f of the SU(2) coupling.

parm  ExcitedFermion:coupFprime   (default = 1.0; minimum = 0.0)
Strength f' of the U(1) coupling.

parm  ExcitedFermion:coupFcol   (default = 1.0; minimum = 0.0)
Strength f_c of the SU(3) coupling.

Contact interactions, production processes

The processes including quark contact interactions are

flag  ContactInteractions:QCqq2qq   (default = off)
Scatterings q q -> q q including contact interactions. Code 4201.

flag  ContactInteractions:QCqqbar2qqbar   (default = off)
Scatterings q qbar -> q' qbar' including contact interactions. Code 4202.

Contact interactions, parameters

mode  ContactInteractions:nQuarkNew   (default = 3; minimum = 0; maximum = 5)
Number of allowed outgoing new quark flavours in the above q qbar -> q' qbar' process. Similar to HardQCD:nQuarkNew for the QCD processes.

parm  ContactInteractions:Lambda   (default = 1000.; minimum = 100.)
Compositeness scale Lambda in GeV.

mode  ContactInteractions:etaLL   (default = 0; minimum = -1; maximum = 1)
Helicity parameter.
option 1 :
option 0 :
option -1 :

mode  ContactInteractions:etaRR   (default = 0; minimum = -1; maximum = 1)
Helicity parameter.
option 1 :
option 0 :
option -1 :

mode  ContactInteractions:etaLR   (default = 0; minimum = -1; maximum = 1)
Helicity parameter.
option 1 :
option 0 :
option -1 :