Simplified cross sections:

Frank reported on the discussions in Les Houches and summarized the main idea behind this ansatz of “model independent” measurements of Higgs productions. Topics of discussion:

• What to do if analyses are not sensitive to certain splits of the parameters. E.g. H->gamgam is likely not strongly separating ggH 0j and ggH 1j
  ⇒ Experiments should then report the sum of parameters they measure, so for the example above sigma(ggH0j)+sigma(ggH1j) and not try to separate these two components. In general, any linear combination of POs could be given as result of a measurement, if this resembles to what the measurement is truly sensitive

• Split of VH seen as too fine grained
  ⇒ Likely true, so experiments will not be able to report all components initially. As above, they should report the sum of the components that is measured

• Some discussion of parameters in VBF and how well the current choice matches possible deviations from the SM
  ⇒ BSM regions still need to be defined, proposals/studies very welcome!
  ⇒ Would be good to have some EFT studies to check how well/badly the current categories cover BSM deviations
  ⇒ Continuous POs as defined for H->VV decays could be a (better) alternative in some cases, e.g. CP-odd BSM contributions. Most parameters for H->VV also valid for VBF and VH. Only for the contact terms (HVff and Hffff coupling) the Q^2 expansion used in H->VV is likely not sufficient

• Studies on continuous POs for VBF and/or VH so far missing but highly wanted

Update on PO for Higgs decays:

Gino reported on updates for POs in Higgs decays. He showed that soft QED radiation effects factorize and can be taken into account. The 20 POs for H->VV, H->Zgam, H->gamgam can be defined as components of partial width.

• Some discussion on how uniquely the components of the partial width are defined
  ⇒ Especially for the CPV components the definition as in the slides might not be the best. An asymmetry could be better. Participants are invited to make a better/more suitable proposal for the CPV components

• Question if the soft QED radiation effects could be taken into account on the experimental side with Photos or similar
  ⇒ yes, this is similar/identical to what was done for the distributions shown in the talk. However, NLO EW normalization (as Prophecy4f gives it in the SM) is obtained “by hand”, but corresponds to a redefinition of the kappa and epsilon parameters.

Tools for PO:

Admir reported on the development of the HiggsPO tool based on FeynRules and Madgraph in order to simulate H->VV, H->Zgam, H->gamgam

• Question if this implementation could also be used for Higgs production.
  ⇒ yes, for LO simulation of Higgs production (VBF, VH). However, for now the HZff contact terms are not implemented for quarks, but this is a trivial extension
  ⇒ no, for NLO QCD simulation

• Question if this implementation works together with MadSpin, which would allow a seamless integration with Powheg for gg->H production

Preparation of a pseudo-observable writeup:

Michael discussed the plans for the joint PO writeup for YR4 and LesHouches. People interested in joining/helping should contact the WG2 conveners. The work will proceed in a similar way as for the EFT basis note. A first draft will be prepared by all people agree to help. This draft is then circulated to WG2 for feedback. Depending on feedback, several rounds of iterations might be needed.