Survey All SM Higgs Production and Decay Processes Campaign

31/S-023 (CERN)



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Minutes of Survey All SM Higgs Production and Decay Processes Campaign meeting
February 13, 2014, 14:00 - 15:30
Participants: ~10 (CERN) + ~30 (Vidyo)

1) Introduction (R. Tanaka)
  • LHC Higgs XS WG will be restructured to start from April 1st, 2014. 
  • The aim of this meeting to survey all accessible SM Higgs production and decay at RUN-2, HL-LHC and beyond
  • Tentative date for the 1st general meeting on June 12 (Thu.) - 13 (Fri.), 2014, when we can discuss the progress on this. 

I. Main production processes [H, qqH, VH]

1) ggF
  • There could be a progress in N^3LO in near future. 
  • Question was raised on approximate N^3LO (M. Spira), detailed answer by S. Forte who also explains how N^3LO PDFs are negligible for ggF. 
  • Both arguments should be investigated in ggH subgroup asap. 
  • Higgs pT studies for the 2HDM are in the starting/comparing phase in POWHEG in addition to MSSM. (A. Vicini)

  • Hγ+2-jets could be an interesting channel to investigate among HV+2-jets category (V=γ,Z,W). (T. Figy) 
  • VH+2jets (EW) is under study with MadGraph5_aMC@NLO. VH+2jets (QCD) is available MadGraph5_aMC@NLO. (F. Maltoni)

3) PDF 
  • PDF4LHC new recommendation with arrival of many NNLO PDF sets? 
  • A new one foreseeable next spring (J. Houston), but no decrease in the spread should be expected. (S.Forte)
  • Maybe top data (ex. rapidity distribution) will give some indication on which set is right/wrong.
  • A new WG for gg-PDFs is about to be created, and working on gg->Higgs PDF uncertainty through the Les Houches workshop. (J. Huston)


II. Associated Higgs production with heavy quarks [ttH/bbH/ccH]

1) ttH 
  • NLO+PS is available since some time in POWHEL and aMC@NLO, and will be soon
    also in SHERPA. (L. Reina)
  • EW could be done (M. Spira) but do not expect NNLO QCD, perhaps fragmentation picture could give insights on the way to build approximations. 
  • Current major interest is ttbar+HF/V+jets, such as ttbb as backgrounds to ttH which are more urgent (L. Reina). 
  • SM backgrounds calculations are more important than more higher-orders (M.Spira agreed). 

2) bbH
  • Same comments as above in 4FS (M. Spira) while 5FS could eventually be done a la Anastasiou.  
  • Plots with uncertainty should (probably) be redrawn (scale variation by 3). 
  • bbH in 4FS  is under study with MadGraph5_aMC@NLO. (F. Maltoni)

3) ccH
  • Numbers can be produced by SUSHI. (R. Harlander)
  • ccH in 3FS has large logs, which is more difficult than bbH. (M. Spira) 

-> bbH and ccH can be discussed in MSSM subgroup. 


III. Associated Higgs production with single top/bottom quark [tHq, WtH, btH, tH, bH, etc.]

  • bq->tHq' is the major channel which amounts to 14% of ttH at 14TeV and some interest in kF=+-1 case. (R. Tanaka) 
  • tbH etc. are available via MadGraph5 in 4FS/5FS. (F. Maltoni)
  • tjH in 4FS/5FS  are both available with MadGraph5_aMC@NLO. (F. Maltoni) 
  • bH can be calculated in 4FS/5FS, but physically most interesting is in MSSM context at large tanβ. 

-> These processes can be discussed in ttH/MSSM subgroups. 


IV. Higgs boson pair/triple production [HH, qqHH, VHH, ttHH, tjHH, HHH]

1) HH
  • Very important channel for HH discovery in RUN-2 and beyond. (R. Tanaka) 
  • gg->HH can be calculated/generated via HPAIR (M. Spira) and other processes via VBFNLO.
  • gg ->HH at NLO and NLO+PS improved by loop effects (including the real loops) is available with MadGraph5_aMC@NLO. (F. Maltoni)
  • NNLO gg->HH calculation exists by D. de Florian et al. (R. Tanaka) 
  • The NNLO calculation is in the EFT and globally rescaled with the Born loop. (F. Maltoni)
  • Open question is what to learn from M. Steinhauser et al.(arXiv:1311.7425) on finite top quark mass effect. 

2) qqHH (VBF)
  • NLO in total/differential in the VBFNLO framework, and public realeas of code soon. (J. Baglio)
  • NNLO calculation exists in the structure function approach, but no public code. (J. Baglio)
  • The NLO and NLO+PS obtained by MadGraph5_aMC@NLO are published and publicly available. (F. Maltoni)
3) ttHH
  • The NLO and NLO+PS obtained by  MadGraph5_aMC@NLO are published and publicly available. (F. Maltoni)

4) tjHH
  • The NLO and NLO+PS obtained in the 5FS by MadGraph5_aMC@NLO are published and publicly available. (F. Maltoni)

5) HHH
  • Forget about HHH, as inaccessible for HL-LHC or even higher energies (J. Baglio). 
  • Maybe at 100 TeV? -> paper by Yao...? (M. Spira) Energy does not help, only Lumi (M. Muehlleitner). 

    -> New HH subgroup being created. MadGraph5 plots are available, THU agreement is needed.


V. Higgs production in association with gauge bosons [VVH]

  • The NLO and NLO+PS obtained by MadGraph5_aMC@NLO are published and publicly available (F. Maltoni). 

 -> WH/ZH subgroup can cover this process. 

VI. Higgs production in association with a gauge boson and two jets [qqHV]
  • Interesting channel as qq->HWqq amounts 2% of VBF and 5% of WH. interest for Yb measurement (D. Rainwater 2001). 
  • The NLO and NLO+PS for HVjj (EW) can be tried with MadGraph5_aMC@NLO.  (F. Maltoni). 

-> VBF subgroup can cover this process. 


VII. Gauge boson scattering [WW→WW, WW→HH, etc.]

  • Very important processes to probe the physics potential at very high-energy colliders. (R. Tanaka)  
  • Can be studied via POWHEG VBF, VBF@NLO, MadGraph5_aMC@NLO, Phantom, etc. 

-> VBF subgroup can cover this process. 


VIII. Rare process and decay [qq→Hγ, t→cH, etc.] [quarkonia J/Ψ(Υ)+γ, γ/Z/W+P, etc.]

1) BR uncertainty
  • PU heavily depends on lattice input, ex. quark mass. (M. Spira)
  • Non-perturbative effects (ex. alpha_s) are neglected, expectations too optimistic? (M. Spira)

2) Rare decays
  • Probably only channels with photon (to replace Z in the listed channels in VP decays) might be visible. 

-> To be followed up in BR subgroup for common framework for THU and PU. 

Minutes taken by CGRS.
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    • 2:00 PM 3:30 PM
      Discussion material 1h 30m
      Speakers: Chiara Mariotti (Torino), Rei Tanaka (LAL)