Notes from live discussion on STXS beyond 1.3 on Nov. 15 during Higgs WG general
assembly at CERN.


General:
===========
* Define and consider two targets with somewhat different timelines/urgency:
- Stage 1.3 (Run2+3): More urgent, preferably only "easy" additions/splits.
- Stage 2 (HL-LHC 1000/fb): More time for studies, but nevertheless start now.


ggH
===========

* Stage 1.3:
- Clarify that it includes gg+bb+cc -> H
- Add more bins at low pTH and high pTH

* Stage 2:
- Discussion on Delta phi_jj
(Needs to be studied, need to decide whether it is worth for itself or primarily
as background for VBF. The latter is more likely and would then mimick the
splits in VBF.)

- Discussion on whether to consider alternative binnings in some branch of the
tree instead of keeping all bins fully exclusive.
(No final conclusion, but added complications makes it unlikely to be viable.)


EW qqH
===========

* Stage 1.3:
- Boosted VBF: Split out higher pTH for mjj > 350
(Needs to be studied how many mjj splits to keep at higher pTH,
probably need at least mjj = 700 GeV boundary due to backgrounds.)

- Boosted hadronic VH: Split hadronic VH bin into pTH?
(Need to study where it goes. It'll be more complicated if significant fraction
ends up in 0,1-jet bins, if so see Stage 2 below. Bin in pTH or some effective 
pTV = pTjj, since V is not defined but would align better with leptonic VH.)

- Split in Delta phi_jj to target CP sensitivity
(Would like to have it for 1.3, but needs studies/concrete proposals: Likely
need (at least) 4 Delta phi_jj bins. Key question is which mjj bins to split,
interplay with pTHjj cut, otherwise run into too many bins.)

* Stage 2:
- Discussion on splitting out VBF+gamma
(Would have to happen by definint 0-photon and >=1-photon bins, one key
complication is that currently high-pT photons would be reconstructed as STXS
jets, requires to change jet definition and hence all currently defined bins.)

- More discussion on boosted hadronic VH.
(Study if feasible and how to adapt jet definitions to
account for boosted large-R jets to reorganize 0, 1-jet bins.)


leptonic VH:
===========

* Stage 1.3:
- Add more pTV bins
- Experiments are encouraged to also measure jet bins (e.g. to gain some 
sensitivity to qq->ZH vs. gg->ZH.) Could upgrade 0-jet split from dashed to 
solid everywhere.

* Stage 2:
- Discussion on adding another/alternative 2nd variable
(should probably keep jet bins, but could add Delta phi_ll or m_Ttot)

- Bin in pTH or pTV
(Not unless strong motivation, since Z->ll can measure pTV much better while
other channels can measure them equally well or not. One motivation would be to
allow combination with hadronic VH if that is binned in pTH.)


ttH:
===========

* Stage 1.3:
- Clarify/generalize it to include tH
- Add more pTH bins

* Stage 2:
- Discussion on possible 2nd variable
(Needs studies what is useful but also feasible to have well-defined.)