Light Higgs subgroup

Goal of the group

Group Contacts

Work plan

  1. Coupling parameter models (X is still to be exactly defined. Functional expressions for Xg, Xgluon are needed for 2. and 5.)
    1. One parameter model with one scale mu : already available from 2011 results
    2. Two parameter model with Xg related to the gauge couplings and Xf related to the Yukawa coupling. Ratios within the gauge and fermion couplings as in the SM. Interference terms, if they can't be factorized by a clever choice of X, as in the SM.
    3. Four parameter model with Xg, Xf and Xg for the photon decay and Xgluon for the gluon decay/production. Ratios within the gauge and fermion couplings as in the SM. Interference terms, if they can't be factorized by a clever choice of X, as in the SM.
    4. A model with XW, XZ, Xt, Xb, Xg, Xgluon, (+ Xtop if ttH production gets available). Interference terms, if they can't be factorized by a clever choice of X, as in the SM.
    5. A model with XW, XZ, Xt, Xb, Xtop (assuming no new particles in the gamma and gluon loop). Interference terms, if they can't be factorized by a clever choice of X, as in the SM.
  2. So far available options for X (discussion is ongoing an so far no agreement on a representation. Proposals are welcome!):
    1. some coupling strength scale factor gi that would appear directly at the Higgs vertex (e.g. s(WH)~gW2 for i=W)
    2. the partial decay width Gi (e.g. s(WH)~GW for i=W)
    3. Separate by observable initial/final states (e.g. 4m instead of ZZ) -> postpone for now because of limited available data
  3. Relative and absolute measurements
    1. Without further assumptions one can fit for (If all correlations are kept in the fit, both are strictly identical)
      1. ratios X_i/X_j and one global scale mu=X_j2/Gamma_H
      2. X_i/sqrt(Gamma_H)
    2. Assumptions for an absolute coupling measurement:
      1. no invisible/undetectable decays
      2. only the undetectable SM decays from H->cc, H->gg, ... and these are calculated by assuming that X_c==X_b or something similar.
      3. Gamma_W<Gamma_W(SM)
      4. Anything else?
    3. Start with C.1, C.2.b, C.2.c
  4. Can combine any option in C with every coupling parameter model in A

Action items

  1. Agree on a definition for coupling parameters that is well defined from the theory side and usable in an experimental fit
  2. Calculate theory uncertainties for whatever coupling parameters are used or give at least some limit estimate on the uncertainty
  3. If we have to continue with LO coupling parameter definitions, give some rough estimates for the uncertainties
  4. Check with jet group if additional uncertainties appear for a coupling fit due to analysis in exclusive jet bins

Available Tools

Results

References

Meetings

  1. Kickoff
  2. Couplings and tensor structure
  3. t.b.a.
  4. Sixth LHC Higgs Cross Section Workshop

Links

-- ReiTanaka - 23-Apr-2012

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Topic revision: r6 - 2012-05-14 - MichaelDuehrssen
 
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