Process 286 represents the production of a pair of real photons in association with a jet. Since this process includes two real photons, the cross section diverges when one of the photons is very soft or in the direction of the beam. Thus in order to produce sensible results, the input file must supply values for both ptmin_photon and etamax_photon. This will ensure that the cross section is well-defined.
The calculation of process 286 may be performed at NLO using either the Frixione algorithm [1] or standard cone isolation. This process also includes the one-loop gluon-gluon contribution as given in ref. [2]. The production of a photon via parton fragmentation is included at NLO and can be run separately by using the frag option in part. This option includes the contributions from the integrated photon dipole subtraction terms and the LO QCD matrix element multiplied by the fragmentation function.
The phase space cuts for the final state photons are defined in input.ini, for multiple photon processes such as 285 - 287 the pT’s of the individual photons (hardest, second hardest and third hardest or softer) can be controlled independently. The remaining cuts on Rγj, ηγ etc. are applied universally to all photons. Users wishing to alter this feature should edit the file photon_cuts.f in the directory src/User.
The calculation is described in Ref. [3].
Process 286, corresponding to the production of a pair of real photons in association with a jet, can be computed at NLO. Since this process includes two real photons, the cross section diverges when one of the photons is very soft or in the direction of the beam. Thus in order to produce sensible results, the input file must supply values for both gammptmin and gammrapmax. This will ensure that the cross section is well-defined.
The calculation of process 286 may be performed at NLO using either the Frixione algorithm [1] or standard cone isolation. This process also includes the one-loop gluon-gluon contribution as given in ref. [2]. The production of a photon via parton fragmentation is included at NLO and can be run separately by using the frag option in part. This option includes the contributions from the integrated photon dipole subtraction terms and the LO QCD matrix element multiplied by the fragmentation function.
The phase space cuts for the final state photons are defined in input.ini, for multiple photon processes such as 285 - 287 the pT’s of the individual photons (hardest, second hardest and third hardest or softer) can be controlled independently. The remaining cuts on Rγj, ηγ etc. are applied universally to all photons. Users wishing to alter this feature should edit the file photon_cuts.f in the directory src/User.
The calculation is described in Ref. [3].
nplotter_gmgmjt.f is the default plotting routine.
[1] S. Frixione, Isolated photons in perturbative QCD, Phys. Lett. B429 (1998) 369 [hep-ph/9801442].
[2] Z. Bern, L.J. Dixon and C. Schmidt, Isolating a light Higgs boson from the diphoton background at the CERN LHC, Phys. Rev. D66 (2002) 074018 [hep-ph/0206194].
[3] J.M. Campbell and C. Williams, Triphoton production at hadron colliders, Phys. Rev. D 89 (2014) 113001 [1403.2641].