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Discussion on Higgs boson pair production within the LHC Higgs Cross-Section Working Group

----- Maggie's talk : NMSSM Hh benchmarks

- Ramona : origin of 13% uncertainty?

BR, but also from mH because of the renormalisation scheme)

- Arnaud : sl 7, why bbgg starts at higher masses?

bounds from exp. measurements

also from the 100-103 mA range (lower bounds decreases when mA increases)

- Arnaud : how about bbVV (V = W,Z) final states?

pseudoscalar : not interesting

singlet-like : expected to be tiny

in NMSSM, the "golden" channels are bbgg, bbtt, bbbb. In extended scalar sectors in general the 4V final state is not favoured.

- Luca : max xs for various mA?

few mass values from experiments as input

- Luca : kinematic differences between H and A (or maybe a MC exists)?

cannot be provided at the moment

but no big differences expected (only in relative polarisation of decays), but to be investigated in more details (M. Spira)

- Luca : sl 7 : bbtt and ttbb overlap perfectly?

yes

- Arnaud : you mention only ggF, can you have associated productions?

low tan beta scenario is interesting in NMSSM, associated production in not interesting in this regime

----- Tania's talk : two real singlet extensions in bbbb final states

- Luca : sl 15 : difference between BP2 and BP3?

just the mass hierarchy : m1 > m2 > m3

- M. Spira : are higher order corrections applied or is it at LO?

all scalar decays are tree level, production has radiative corrections

D. Barducci : not applied in the paper quoted in the talk

- J. Baglio : there is a pattern for the exclusion, where does it come from?

should look into which search is creating that effect, probably not a numerical artifact

- Arnaud : which benchmakrs are sensitive to bbVV?

BP2 and BP3 are promising for bbVV, mostly BP3

note that in one case the VV pair would be very off-shell (when the non-SM scalar decays to VV)

----- Haitao's talk : HH production at N3LO in QCD

- J. Baglio : on sl. 8, is this consistent with the heavy mt limit everywhere?

here no mt effect is included

- J. Baglio : the LO here is the full LO and not in the heavy mt limit, while blue is a Born-improved limit

- Javier : sl 14 : at NNLO the FTapprox does not lie within the values from this approximation --> this is not necessarily a good way to estimate the error

----- Jonatan's talk : top quark mass scheme uncertainty

- Arnaud : looking at NLO, scale and mt are similar. At N3LO/NNLO-FTapprox, scale becomes small. How about mt uncertainty, it applies to all orders?

the only way to reduce it would be to evaluate it at NNLO with full mt dependence

M. Spira : note that full NNLO calculation is something more that ever done so far (not sure if feasible in the new future)

J. Baglio : this is the state of the art at this order. How to include it in an analysis, which type of recommendation?

Spira, Baglio : can just be rescaled to higher order for N3LO, not for NNLO-FTapprox (the latter has the extra mt effects in the FTapprox taken into account, some refinement is needed there)

- Follow up M. Spira : there are 2 questions. 1) the uncertainty band , 2) the central value. 1) cannot be reduced now (because would need full NNLO calculation).

- Arnaud : how about variations with klambda, will that change significantly?

Spira : most likely should be independent from kl because the uncertainties are the same betweem box and triangle, and kl just changes their ratio

J. Baglio : especially differentially, at high mHH the box diagram dominates and this is where the uncertainty is larger

conclusion : this is conservative and valid for every klambda

- Ramona : how to make this result available for the 2HDM

Stephen : since it depends on the parameter point chosen : will be evaulated for different specific scenarios (benchmark points). Could be done in grids and after interpolated as for the self-coupling.

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