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Minutes WG1 periodic meeting
Thursday 26 Mar 2020
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https://indico.cern.ch/event/896045/
25+ people attending
# The geometric SMEFT
Andreas Helset
- So in addition to symmetry, imposing geometrical structure restricts the number of couplings of the EFT?
No, the geometric formulation is not an imposed constraint, it is a way of organising and resumming contributions at all orders for specific classes of couplings.
- Are there any modifications to the ghost sector from higher-dimensional operators?
yes, the ghost sector also fits in the geometric interpretation and the metric is the same as for the corresponding gauge fields.
- Can you learn something from the geometric description on anomalous triple/quartic gauge coupling correlations and how to compare to the HEFT for instance?
Not really at this stage, because we could only derive all-order results for couplings with up to 3 legs. The reason is that for these vertices one can show that it's always possible to choose a basis where all dimension d>6 corrections have the same structure as in the d=6 basis, multiplied by powers of (H⁺H). For quartic gauge coupling this does not hold. In fact there are new Lorentz structures entering at d=8. It is possible that the number of structures saturates at d=8 and higher order corrections are obtained multiplying those operators but (H⁺H) but we haven't studied this yet.
# Probing Higgs-portal dark matter with vector-boson fusion
Eric Madge
- Is it possible to look at Higgs Strahlung?
Probably. As far as we could find, VBF gives the best constraints on h > invisible, so this is why we chose this channel.
- Background simulation question.
The method is used to be able to reintepret the experimental results.
# Diphoton production in VBS at NLO QCD
Ivan Rosario
- Question about PS.
It is expected to make predictions more reliable in some corner of phase-space.
# Study of aQGC in vector boson scattering
Yu-Chen Guo
- So here is my point for the speaker: the saturation of the unitarity bound does not rule out the effective theory (SMEFT in this case). It just means that a perturbative treatment is not adequate. So I disagree with the phrase "the unitarity bound is stronger than experimental constraints": the unitarity bound does not directly constrain the parameters of the Lagrangian, whereas the experimental data does. Unitarity saturation just indicates that the theory with those parameters requires other methods.
Yes.
- Are the experiments using r1 and r2?
I do not know.
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