Centre for Cosmology, Particle Physics and Phenomenology (CP3)
Université Catholique de Louvain
Chemin du Cyclotron 2
1348 Louvain-La-Neuve, Belgium
mail : email@example.com
Last modification : 2012-11-05
Back to home page
The rare Higgs decay, , is implemented in the UFO model "h_ZGamma" (version v1.0) and allows the user to study the full Higgs production process, , since it includes,
- all tree-level Standard Model interactions
- the Higgs Effective Field Theory, i.e. interactions according to the following low-energy lagrangian,
- a local H-Z*-Gamma interaction allowing for an off-shell Z boson as calculated in Nucl.Phys. B259 (1985) 137 with the exact contribution from the W loop and from the massive bottom and top quarks.
The model described above has been tested in several ways,
- analytic formulae for the Higgs partial width from Nucl.Phys. B259 (1985) 137 and arXiv:hep-ph/0503172 have been cross checked against each other,
- the computed Higgs partial width has been cross checked with HDECAY, a program of Michael Spira implementing the partial width of reference arXiv:hep-ph/0503172,
- kinematical and differential jet rate distributions have been checked with matched samples up to 2 extra jets.
Please, notice that a specific version of MadGraph5 is dedicated to this process to support formfactors and is available here or via launchpad :
bzr branch lp:~maddevelopers/madgraph5/formfactor/
Once the right version of MadGraph5 is downloaded as well as the h_ZGamma model, extract the tarball h_zgamma.tar.gz in the directory "formfactor/models/" and run MadGraph5 as usual :
>import model h_Zgamma
>generate p p > h > z a
Below, the reader can find matching plots (a,b,c) for samples with 0, 1 and 2 jets as well as an illustration of the pT distribution (d) of a Higgs boson of 125 GeV produced at the LHC running at 8 TeV.
Figure: (a) differential 0 -> 1 jet rate distribution using the matching of matrix elements and parton showers,
(b) differential 1 -> 2 jet rate distribution,
(c) differential 2 -> 3 jet rate distribution,
(d) Higgs (125 GeV) pT distribution of the matched pp -> h -> e- e+ a + 0,1 jet samples, LHC@8TeV.