= Zh production =

This page contains the codes for calculating cross sections or generate event for Zh associated production at LHC through gluon fusion. 

'''Authors :  Benoit Hespel and Eleni Vryonidou'''

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== SM ==

[[Image(ZH_diag.png)]]

We calculated the gluon-gluon fusion contribution to Zh production. This is formally part of the NNLO QCD corrections to ZH production in proton-proton collisions. We generate events using the infinite top mass EFT and then with a dedicated reweighting code we introduce the exact quark mass dependance of the loops. 

This code has been checked against the program vh@nnlo (arxiv:1210.5347 [hep-ph]) and can be downloaded here [attachment:ZH_code.tar.gz ZH_code]

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== 2HDM ==

We calculated the gluon-gluon fusion contribution to Zh_i production (where h_i stand for (h,H,A) with the usual notation: h for the light scalar neutral boson, H for the heavy one and A for the pseudoscalar boson). Like in the SM this is part of the NNLO QCD corrections to Zh_i production in proton-proton collisions. We also used exactly the same technique as before (reweighting of the EFT). 

Our results are in agreement with arxiv:1307.8122v2 [hep-ph], Harlander, Liebler, Zirke, vh@nnlo version 2.0beta (unpublished).

For pheno studies assistance can be provided to obtain parameter cards for any given 2HDM input that can be used with the following codes.

=== Zh production ===

In the 2HDM there is one additionnal diagram contributing to Zh production with respect to the SM above: the s-channel A contribution.

[[Image(Zh1_diag.png)]]

The code can be downloaded here [attachment:Zh1_code.tar.gz Zh_code]

=== ZH production ===

[[Image(Zh2_diag.png)]]

The code can be downloaded here [attachment:Zh2_code.tar.gz ZH_code]


=== ZA production ===

[[Image(ZA_diag.png)]]

The code can be downloaded here [attachment:ZA_code.tar.gz ZA_code]