Minutes of Survey All SM Higgs Production and Decay Processes Campaign meeting

February 13, 2014, 14:00 - 15:30

InDico: http://indico.cern.ch/event/297849/

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.

Discussions

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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)

2) VBF, WH/ZH

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)

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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.

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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 k_F=+-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.

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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.

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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.

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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.

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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.

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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.

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Minutes taken by CGRS.