MC20 and MC23 X->SH(bbyy) swapped decay mode

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JIRA ticket

ATLMCPROD-11562

Checklist for approval

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• I have followed the guidelines in McSampleRequestProcedure
• I have provided the ATLMCPROD JIRA ticket where the request has been discussed
• The request has been approved by the PA/CP group
• The pipeline has run and the status is green (still check the CI job output - if you see any errors report to the repository maintainers)
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• CI jobs have not been skipped (if jobs have been skipped, the requesters should provide a reason for skipping and confirmation from the PMG conveners is necessary before merging)
• Check that no log.generate.short files are included in the commit to be merged to master. If such files are present, it indicates that something went wrong in the pipeline. Check the job logs and contact the package maintainers if needed.
• Check that the title of the MR is descriptive enough (if not ask the requester to modify it)
• Check that the DSID range assigned is correct (500000-999999) and corresponds to right generator block
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802xxx/802597/mc.Py8EG_A14NNPDF23LO_XHS_X1000_S70_HbbSyy.py

+include("Pythia8_i/Pythia8_A14_NNPDF23LO_EvtGen_Common.py")
+evgenConfig.generators = ["Pythia8", "EvtGen"]
+evgenConfig.process     = "gg->X->SH->bb+yy"
+evgenConfig.contact = ['Jason Veatch <Jason.Veatch@cern.ch>']
+evgenConfig.description = "Generation of gg > X > SH where S decays to yy and H decays to bb"
+evgenConfig.keywords = ["BSMHiggs"]
+
+genSeq.Pythia8.Commands += ['Higgs:useBSM = on',
+                            'ParticleDecays:mSafety = 0.0',
+                            'HiggsBSM:gg2A3 = on',
+                            'HiggsA3:parity = 1',
+                            'Higgs:clipWings = on',
+                            'Higgs:wingsFac = 200',          # cut the mass distribution of the resonances at +/- 200 * mWidth
+                            '36:m0 = 1000',                  # mass of X
+                            '36:mWidth = 0.01',
+                            '36:doForceWidth = yes',
+                            '36:addChannel = 1 1 100 25 35', # channel is ON, branching is one, ME=100 use ME calculation recompute width with BR, H+S
+                            '36:onMode = off',
+                            '36:onIfMatch = 25 35',          # Exact decay channel X-> H S
+                            '36:mayDecay = on',
+                            '35:mMin = 10.0',                # lower limit of the allowed mass range generated by the Breit-Wigner of S
+                            '25:mMin = 50.0',                # lower limit of the allowed mass range generated by the Breit-Wigner of H
+                            '35:m0 = 70',                  # mass of S
+                            '35:mWidth = 0.01',
+                            '35:doForceWidth = yes',
+                            '25:onMode = off',
+                            '25:onIfMatch = 5 -5',          # H-> bb
+                            '35:onMode = off',
+                            '35:onIfMatch = 22 22'            # S-> yy
+                            ]