Antoine Laureys

Centre for Cosmology, Particle Physics and Phenomenology (CP3)
Université Catholique de Louvain
Chemin du Cyclotron 2
1348 Louvain-La-Neuve, Belgium
mail :
Last modification : 2012-10-17

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Below, you will find a model which allows to generate unweighted events for two Higgs boson production through gluon fusion in the Standard Model.
It includes the s-channel with the trilinear Higgs coupling and the contribution from the box diagrams with the exact top quark mass dependence. However, the bottom quark contribution is neglected.
Several checks were made to validate the implementation. The matrix element coïncides point-by-point in phase space with MadLoop, the cross section was succesfully checked with Michael Spira's code (hpair) and finally we compared distributions with an independent implementation of the process.

In order to use this model, please follow the next steps :
  1. Download MadGraphv4 here.
  2. Untar the this tarball and move the heft2/ directory in the directory of MadGraphv4 containing the other models, i.e. Models/.
  3. Use MadGraphv4 as usual with the proc_card.dat and run_card.dat given in the tarball.
Further comments :
  1. In the proc_card, two processes are used. One with particle b0 and one without this particle. This is only an artefact and doesn't correspond to a physical particle.
  2. In the run_card, the parameter "fixed_couplings" should be set to FALSE such that the form factors are evaluated point-by-point.
  3. It is not possible to add decays of the Higgs in the proc_card, however you can use the DecayPackage on the MadGraph website to decay the Higgs afterwards.
  4. Executing the python script bin/Passto_gfortran might be usefull in order to avoid errors.