====== Higgs EFT ======

**Project Description**

-> Comparisons of SMEFTsim and SMEFTatNLO running both at LO to check the consistency
Especially for ttH and ZH-> the operators affecting these production channels will appear in ggZH.
The definition of operators in the NLO model can be found in http://feynrules.irmp.ucl.ac.be/attachment/wiki/SMEFTatNLO/definitions.pdf and in page 49 of https://arxiv.org/pdf/1709.06492.pdf for the LO model.
The main difference in the implementation is for complex operators, in SMEFT LO there is a phase and an absolute value whereas only one real value can be modified in the NLO model.
   
-> Study of ggH and ggZH at NLO. Similar studies published:
   https://arxiv.org/pdf/1601.08193.pdf (ggZH, limited set of operators studied)
   https://arxiv.org/pdf/1708.00460.pdf (ggH)
For the generation of the interference term we need to interfere tree level (from the EFT) with loop-induced processes (from the SM). Madgraph is not able to do it for the official versions, but some documentation on how to do it has been gathered:
   https://cp3.irmp.ucl.ac.be/projects/madgraph/wiki/LoopInducedTimesTree
It can be also done using the reweighting module.
Link to the STXT Rivet routine:
   https://gitlab.cern.ch/LHCHIGGSXS/LHCHXSWG2/STXS/Classification 
that also provides histograms of common kinematic variables. 


**Interested Participants**

María Moreno Llacer, Marco Delmastro, Ana Cueto, Nicolas Berger, Paolo Francavilla, Saskia Falke, Daniel de Florian, Mauro Donega, Josh McFayden, Add your name :)