Les Houches

(accessible to everyone, editing rights to conveners and organizers)

Techniques and calculations for SM phenomenology:

• Calculations/tools:
  • expected precision for fundamental Standard Model processes at 14 and 100 TeV; what calculations are needed to match this precision?
  • NNLO and N3LO; status/challenges/prospects
  • theory uncertainties; more rigorous estimates? correlations? In particular, theory uncertainty for EW corrections?
  • usage of NNLO results; grids seem to be a real bottleneck now for precision work
  • resummation in analytic and parton shower calculations
    • uncertainty for 'softly-vetoed' distributions
    • comparisons of jet veto calculations
    • tuned comparison of NLL parton showers; sub-leading power corrections

• PDFs:
  • followup on PDF4LHC21 benchmarking exercise; better understanding of tolerances, tensions
  • EW corrections/EW PDFs; how to provide consistent calculations (lepton definition with QED effects)
  • Electron-ion collider (EIC); what will EIC tell us? how do we prepare for that?
  • N3LO PDFS; how firm are changes to the gluon, and what should be done for benchmark Higgs cross sections; progress on splitting functions
  • PDF uncertainties, i.e. hopscotch vs Monte Carlo sampling
  • intrinsic charm
  • theory uncertainties/correlations in fit. Double counting?
  • quark-gluon discrimination for PDF determination

• Higgs/EW sector:
  • understanding the SM for high Higgs pT; role of top mass corrections/scheme (MSbar vs on-shell); how to improve channel sensitivities; VBF signal at high pT; gluon-fusion background in VBF phase-space
  • Parton-shower uncertainties in VBF
  • polarisation measurements (for diboson/VBS as well): theory/experiment interplay
  • prospects for tri-boson production. Are there any theoretical limitations?

• Top:
  • ttW; tension; can new calculations resolve it?

• Jets:
  • flavor tagging of jets; matching what theorists can predict (IR safety) and what experimentalists can measure [overlap with Jet substructure techniques, see below]
  • use heavy flavor jets for W+c (→strange quark PDFs) and Z+c (→intrinsic charm)
  • further investigations/understanding of jet R-dependent scale uncertainties

• Miscellaneous
  • forward physics → FASER. Anything needed from SM point of view?
  • W mass:
    • (non-perturbative) modeling
    • new ideas/methods (asymmetry)
    • determination at e+e-
    • theory agnostic determination; how agnostic?

Jet substructure techniques:

• detailed comparison between recently proposed jet flavour algorithms
• starting from state-of-the-art ML-taggers, estimate how much they are correlated to the physics in the measurements of substructure we already have. Discuss good procedures to best tune MC to describe ML-taggers. Discuss good procedures to estimate uncertainties on ML-taggers, given the physics understanding of various effects (an example is scale-variations, where our constraints from data are certainly stronger than the factor 2 variations in many cases, but sometimes the opposite).
• take stock of how well most recent generator developments have improved description of multiple new measurements of substructure. (Followup from a previous Les Houches 2015 on q/g-tagging)

….

Here for convenience

Jet substructure techniques:

• Interplay of jet substructure with other groups (e.g. jet substructure for EW measurements like VBF, semileptonic VV, etc.)
• Snowmass jet substructure report (JSS at future colliders) [work + discussion]
• What can we do with previous colliders, in light of the LHC [discussion]
• Comparing new unfolding methods
  • Accord on unbinned results (?)
• Probing the latest MC generators (PB algorithm, PANScales, Deductor…) with jet substructure
  • Finite N_C, beyond LL, …

Monte Carlo:

• Non-perturbative uncertainties
  • common hadronisation interface and variations
  • theoretical understanding
  • differences in tuned comparisons
  • pheno impact for certain classes of processes (e.g. VBF/VBS)
• Shower accuracy studies
  • comparing different schemes on higher orders, evaluate phenomenological impact
  • Subleading colour and interplay with colour reconnection
  • New sampling methods and algorithms versus machine learning techniques
  • Accuracy of merging resummed calculation versus ME+PS paradigms
• Photon physics, modelling of fragmentation
• Heavy flavour matching
  • review of existing measurements
  • Connecting precision calculation, fragmentation and decays
  • partons at 100 TeV
• Common LHC event bazaar
• Status and needs for electroweak corrections and radiation in shower algorithms
• Machine learning and adaptive Monte Carlo methods

SM Higgs Topics:

• ggF
  • N3LO PDFs, small-x
  • EW corrections
  • cuts/differential distributions
• B-quark issues
  • Ttbb, V+HF, VH
  • 4FNS vs 5FNS: bbH, t/H/Z+j QCD EW…
  • Flavour jet algo\
• ggVV
  • Massive results [if we’ll have them, probably yes]
• VBF
  • Factor vs non-factor: TH vs EXP discussion on cuts etc (especially Run3)
• Jet-ology
  • NNLO+NLO res, VH+J, NNLO+decay & fiducial studies
• HH
  • EFTs, H vs HH
• In general, EFT fits etc
• Exp vs theory efficient information exchange
  • Likelihood, discriminators as black box
  • Differential distribution. TH insight for measurements…
• PS issues (SLC, higher logs…, liaise with QCD)
• New opportunity for Run3 (unexplored regions, != cuts etc)
• STXS
  • for decays - binned proposal
• FO/Boosted
  • NLO-Improved NNLO HTL predictions for gg → H(→yy)+Jet in the fiducial region, experimental sensitivity to different decay channels as a function of pt
  • Mixed QCD-EW contributions to higgs (e.g. 2010.09451, 2007.09813)
• Backgrounds
  • Predictions+uncertainty models for backgrounds to ttH production: tt+HF, ggH+HF, tt+V, previous proposal was to estimate ttV EW correction in different phase space regions
• 4FS/5FS
  • bbar → higgs (e.g. 2004.04752)
  • tHj tZj QCD+EW (e.g. 2006.10086), various 4FS/5FS matching issues to consider
• Showers
  • New showers, subleading-colour issues with parton showers and possible effects on Higgs physics (PanSccales 2011.10054; Forshaw, Plätzer et al 2003.06400, 2007.09648, 2011.15087, 2012.15215)