Released by Margarete Mühlleitner, Marco Sampaio, Rui Santos and Jonas Wittbrodt

A Fortran program for the calculation of the decay widths and branching ratios of the Higgs bosons in the N2HDM, i.e. the CP-conserving 2HDM extended by a real scalar singlet field.


The Fortran program N2HDECAY calculates the decays of the Higgs bosons in the N2HDM. The N2HDM features 3 neutral CP-even Higgs bosons H1, H2 and H3, one CP-odd boson A and two charged Higgs bosons H+/-. The program includes in the decay widths the most important higher order QCD effects and consistently neglects all EW corrections. They are not available for the N2HDM and contrary to the QCD corrections, cannot be taken over from the SM case.

A detailed description of the model and the program can be found in M. Mühlleitner, M. Sampaio, R. Santos, J. Wittbrodt, JHEP 1703 (2017) 094 .


N2HDECAY consists of the main program file n2hdecay.f. Further linked routines are dmb.f, elw.f, feynhiggs.f, haber.f, hgaga.f, hgg.f, hsqsq.f, susylha.f. The input file is named n2hdecay.in. It is the original hdecay.in input file supplemented by additional input values for the choice of the N2HDM, the type of Yukawa couplings and the setting of the mass values and parameters. The N2HDM decay widths are calculated by setting in n2hdecay.in 2HDM=1 and N2HDM=1. The meaning of the remaining input values is explained in the header of the file n2hdecay.f. The output files which are generated are br.x_N2HDM_y Here x denotes the Higgs boson, i.e. x=H1, H2, H3, A, H+. The files with y=a include the fermionic decays, with y=b the bosonic decays and with y=c,d the Higgs-to-Higgs decays, the Higgs-to-gauge-Higgs decays and the total width. Note that the Standard Model decay widths and branching ratios are obtained by setting COUPVAR=0, 2HDM=0 and N2HDM=0 in the input file.