Area 2 : Predictions and tools C. Degrande, G. Petrucciani · 2020. 10. 22. · Area 2 :...
Transcript of Area 2 : Predictions and tools C. Degrande, G. Petrucciani · 2020. 10. 22. · Area 2 :...
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Area 2 : Predictions and tools C. Degrande, G. Petrucciani
Institut de recherche en mathématique et physiqueCentre de Cosmologie, Physique des Particules et Phénoménologie
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C. Degrande
• Available predictions and tools
• Reweighting
• Uncertainties
• EFT validity
• Unstable particles
Plan
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Available predictions and tools
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C. Degrande
General : •Which basis, which operators are included? •SM input scheme
•𝚲 order, form factors
•Which processes? which observable? •Compare/validate models at LO (E.g. 1906.12310)
Analytical : list the results published (so far?) (~1000 SMEFT papers) •Dynamical resource (updated when new results appear)
Numerical: •List of models •Which generators for EFT? Limitation (Lorentz structures,...)? •Compare generators at LO (E.g. Madgraph vs Sherpa)
At LO
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C. Degrande
• What is available?
• Any analytic results?
• Numerical (SMEFT@NLO 2008.11743, other process specific VBFNLO)
• Which running/scheme of the coefficients?
• Comparison between generators and published results
• Comparison between generators : Madgraph5aMC@NLO vs recola? vs sherpa?
• EW corrections? Match to PS?
At NLO
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https://arxiv.org/abs/2008.11743https://arxiv.org/abs/2008.11743
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Reweighting
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C. Degrande
• Goal: Avoid expensive generation & detector simulation
• Why: many different EFT points/parameters
• How: compute predictions of space points from the same set of generated events, using weights from ratio of matrix elements
• helpful if generating events for the full 2 → N process is not feasible?
Reweighting
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C. Degrande
• Coupling to the generation :
• “weights can be computed only during generation”
• OR “weights can be computed for any LHE event irrespectively of generator”
• Depends on implementation,
• feasible for run 2 analysis
• strategy for run 3 MC generation
• Review approaches & tools: accuracy (NLO, spin correlations, …), validation
Reweighting
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Uncertainties
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C. Degrande
• On the SM predictions :
• Are EFT effects large where SM corrections are also large (large energy spread)?
• On the EFT predictions:
• Higher order in the SM couplings
• Higher order in 𝚲
• Scale (running) and PDF uncertainties (PDF at LO/NLO/NNLO)
• EFT contribution to background
• Scaling the EFT contribution as the SM?
Uncertainties
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EFT validity
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C. Degrande
• Only c/𝚲2 is measured but we need Eexp
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C. Degrande
EFT & scales
Unitarity bound
SM
NP onlySM+NP
1/⇤0
PerturbativityUnitarity
1/⇤2
We measure , what is ?Ci⇤2
⇤
⇠ ⇤
> ⇤ E
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NP only 1/Λ4
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C. Degrande
EFT & scales
Unitarity bound
SM
NP onlySM+NP
1/⇤0
PerturbativityUnitarity
1/⇤2
+Form Factor
We measure , what is ?Ci⇤2
⇤
⇠ ⇤
> ⇤ E
13
NP only 1/Λ4
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C. Degrande
EFT & scales
Unitarity bound
SM
NP onlySM+NP
1/⇤0
PerturbativityUnitarity
1/⇤2
+Form Factor
Precise : EFT (model ind.) We measure , what is ?
Ci⇤2
⇤
⇠ ⇤
> ⇤ E
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NP only 1/Λ4
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C. Degrande
EFT & scales
Unitarity bound
SM
NP onlySM+NP
1/⇤0
PerturbativityUnitarity
1/⇤2
+Form Factor
Precise : EFT (model ind.)
SM±>100% Assume SM +dim6 only
We measure , what is ?Ci⇤2
⇤
⇠ ⇤
> ⇤ E
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NP only 1/Λ4
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C. Degrande
EFT & scales
Unitarity bound
SM
NP onlySM+NP
1/⇤0
PerturbativityUnitarity
1/⇤2
+Form Factor
Precise : EFT (model ind.)
SM±>100% Assume SM +dim6 only
Unitarity allowed
We measure , what is ?Ci⇤2
⇤
⇠ ⇤
> ⇤ E
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NP only 1/Λ4
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C. Degrande
• Only c/𝚲2 is measured but we need Eexp
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Unstable particles
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C. Degrande
• EFT : • in production (lower number of final state, faster
(NLO))
• decay (as top polarisation)
• or both (ideal theoretically, many approximation from prod x Br to full ME)
• Width depends on 𝚲, how to truncate?
• Which scheme (Complex mass scheme and basis dependence)
Unstable particles (W,Z,t,H)
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