HH Subgroup Meeting / WG3: Extended Scalars meeting (2HDM/Singlets/Triplets)

Europe/Zurich
40/S2-C01 - Salle Curie (CERN)

40/S2-C01 - Salle Curie

CERN

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Christoph Englert (Heidelberg University), Magdalena Slawinska (NIKHEF (NL)), Maxime Gouzevitch (Universite Claude Bernard-Lyon I (FR)), Roberto Salerno (Ecole Polytechnique (FR)), Sally Dawson (BNL)
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LHC_Higgs_XS_HH_Subgroup_Meeting
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LHC_Higgs_XS_HH_Subgroup_Meeting
Description
Meeting of the HH subgroup of LHC Higgs XS working group
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109344031
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Roberto Salerno
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MINUTES OF THE 24TH FEBRUARY 2015 WG3 MEETING


 

Introduction

Renamed the group in “Extended Scalars”. We would like to cover more topics, and have more theory conveners to cover all the topics. The new conveners are Heather Logan, Shufang Fu, Rui Santos and Oscar Stal.

We have a new twiki page for the subgroup

https://twiki.cern.ch/twiki/bin/view/LHCPhysics/LHCHXSWGGM

 

  • Extended scalar sectors with Higgs triplets - H. Logan

https://indico.cern.ch/event/373558/session/0/contribution/14/material/slides/0.pdf

 

Q: When you discuss the existing tools, is there anything missing to calculate sigma*BR for the mode?

A: For 2-2 tree level decays everything is there. Offshell decays and loop induced still needs to be delivered.

Q: What about production xsec?

A: VBF@NLO is available. For g-g fusion: there are no new colors in the model, and it’s type-I, so no bbar enchancement. Probably can use SuShi.

 

Q: For charged Higgs production, what do you use for xsec?

A: VBF@NLO mostly, but we should make a list of all the production mechanisms involved in the model.

 

Q: How does VBF@NLO deal with QCD corrections for charged Higgs? At LO you can radiate photons from quark lines

A: VBF@NLO only handles single Higgs boson production (both neutral and charged)

 

Q: Do you plan to have a dedicated program for this model for decays?

A: We plan to continue working on GMCALC to add loop induced and offshell decays

 

Q: For charged Higgs boson, the pair production should be relevant wrt VBF, right?

A: For higher mass the single production is always dominant.

 

Q: Are you aware of other groups working on this model? It’s a tight schedule to have deliverables by summer.

A: There’s other groups, we plan to have dedicated meetings, but timezones are a problem

 

Q: For the connection with WG2, since you have violation of the sum rule, would you be able to have a parametrization so this could be implemented in the k_v fit?

A: There’s an upper bound on k_v from doubly charged scalar limits, we can provide that

 

  • Non SM Higgs in 2HDM - S. Fu

https://indico.cern.ch/event/373558/session/0/contribution/15/material/slides/0.pdf

 

Q: Have you investigated these channels to see the prospects in Run2?

A: For the neutral one, we have looked at the VH type decays and this has already been covered by CMS/ATLAS. For the other types (but HH) we have a paper ongoing which should be out in a month.

 

Q: From your discussion you miss the H -> ttbar decay. There’s currently no analysis covering those decays and is also a big theory problem to describe interference effects there.

A: Our studies involve gauge bosons in the final state, but it’s a possibility, especially for the low tanbeta region, but they are very hard at LHC with the large ttbar background. Experiments plan to explore this for Run2. Studies exist for future higher energy machines, where ttbar will be very sensitive.

 

Q: Does this study include the huge interference between signal and background?

A: Not for now, this is a very preliminary study.

 

  • Status of 2HDM and C2HDM after Run 1 - R. Santos

https://indico.cern.ch/event/373558/session/0/contribution/16/material/slides/1.pdf

 

Q: On slide 14 do the colors show the maximum or minimum value?

A: They show the maximum value

Comment: The limits are also very dependent on the width, as the experimental resolution is at a comparable level. This needs to be discussed. In CMS/ATLAS we tend to use the full width formalism and produce limits as a function of width.

 

  • Thoughts on 2HDM benchmarks - Oscar Stal

https://indico.cern.ch/event/373558/session/0/contribution/17/material/slides/1.pdf

 

Q from speaker: What are the experimental needs for the definition of benchmarks?

A: In order for the benchmarks to be used we need predictions in tools that calculate xsec*BR for each benchmark. One problem is that we have to limit the number of benchmarks.

Oscar: yes, we have a limit on the number of benchmarks we can propose. We should try to find the set that best captures the features of the model

 

Q: What is the difference between the Higgs basis approach and the choice of free parameters already used by CMS/ATLAS?

A: What really matters is the choice of the parameters to be fixed that defines the benchmark. We need to make sure the experiments choose a set that allows to explore all the phenomenology of the model.

 

Plan: the 2HDM subgroup conveners will make a first proposal for a set of benchmarks and make a call to the e-group mailing list to provide feedback and proposals with a deadline. From there the group will try to converge on a limited amount of benchmarks, also with experimental feedback.


 

  • benchmark request from the off-shell subgroup

https://indico.cern.ch/event/373558/session/0/contribution/18/material/slides/0.pdf

 

Nicolas Kauer et al made some slides but they couldn’t connect to the meeting to present them. It was agreed that people will read them offline and if needed they continue discussion in the egroup mailing list.

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