WG3: Heavy Higgs width and interference discussion

40/S2-C01 - Salle Curie (CERN)

40/S2-C01 - Salle Curie


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These are some points for discussion we put before the meeting to give the opportunity to people to think in advance! ------------------------------------------------------------------------ - How to do the parameterisation vs width and mass. - How to account for the dependence on the signal cross-section not just the width and mass - Does the parameterisation allow for arbitrary width (and interference) as needed in the 2HDM (or use e.g. 0.1 steps which is OK for EWS)? - Do we go up to the SM width or beyond as well (again needed for 2HDM)? - Which generators to use to parameterise the interference? Is this for ggF as well as VBF? - Which final states? Only ZZ -> 4l; other ZZ; WW? - Which masses, widths, ...? - What about bbH for the future? - Is this generator-level only and or reco-level checks are needed as well? - Does width affects the kinematics/acceptance? - What type of interference is covered? - Only heavy H + VV continuum? - h+VV continuum (should just be a special case of above I guess)? - h+ H interference, which becomes important when H is wide - How do you account for the large contribution of off-shell h->ZZ to the ZZ background spectrum at low tan(B) in 2HDM type 1/2 and high tan(B) in type 2? - How to apply the interference - Only to S or S+B? - Does CMS plan to update/change this strategy for 13 TeV - On what time scale? More general question: - What models to be used for the interpretation in and over which regions of parameter space? (this may have to wait till we see the benchmarks proposal from the Extended Scalar group) - How will they take into account variation over 2HDM - H strength/width - h strength/width - ggF/VBF/bbH ------------------------------------------------------------------------

Summary of the Width/Interference meeting


May 4th, 2015, 17:00 - 18:30

Indico link: https://indico.cern.ch/event/389216/


Objective: to start the process in order to establish a common procedure between ATLAS and CMS for H -> WW/ZZ signal and background modeling and interpretation


Some discussion points worth mentioning:

  • CMS has claimed that mostly H->4l has any significant effect; ATLAS suggested that there is an effect also on H->WW and H->ZZ->2l2q; needs to be checked

  • Suggestion that for 2HDM at least only the narrow width region is relevant, since large width regions are disfavoured by the existence of a SM-like h

  • CMS H->4l shape parametrization that was discussed in detail in the talk by Stefano is implemented in RooFit and it will become available to the everyone


Major open points that need to be discussed and followed up:

  • interference in the bbH production (Frank Krauss expressed interest to have a look)

  • treatment of h+H interference (has not been included in the CMS analysis; conflicting references; need to be checked by theory experts)

  • interference is applied only to S currently; need to check whether we need to apply to S+B

  • connection to the 2HDM benchmarks to be discussed later this month


Conclusion and Action items:

  • a twiki is going to be prepared to explain the full procedure for the HZZ4l parametrization so that it is possible to be reproduced by anyone. The procedure can then be reviewed by theorists.

  • it was suggested that this after the review gets to the Yellow Report 4 without an intermediate internal note


There are minutes attached to this event. Show them.
    • 17:00 17:20
      ATLAS: Run-I strategy and points for discussion 20m
      Speaker: Nick Edwards (University of Edinburgh (GB))
    • 17:30 18:00
      CMS: Run-I strategy and tools 30m
      Speaker: Nhan Viet Tran (Fermi National Accelerator Lab. (US))
      • HZZ4l lineshape: analytical parametrization 10m
        Speakers: Stefano Casasso (Imperial College Sci., Tech. & Med. (GB)), Stefano Casasso, Stefano Casasso (Universita degli Studi di Torino-Universita e INFN)
    • 18:00 18:30
      Discussion 30m