User Tools

Site Tools



Topics for Consideration

(Editing this page requires special privileges: Conveners, managers)

List of brainstorming session June 6


  • machine learning
  • comprehensive 2-prong study (non-b tags) (W-boson polarization)
  • alpha_s extraction from jet substructure (white whale) e.g. running at high scales (?)
  • assess complementarity to 3-jet/2-jet ratio (or other canonical observables)
  • use cases of quark/gluon tagging (e.g. in H+jets); use in NNLO?
  • jet substructure for understanding showers
  • J/Psi in jets, hybrid substructure, flavour tagging
  • fat jet definition

parton shower issues

  • matching variations
  • study angularities
  • beyond LL uncertainties
  • shower starting scale choice (e.g. consistency conditions, test limits)
  • comprehensive shower tuning (+had+MPI) + PDF order
  • heavy flavour modelling
  • resummation versus fixed order e.g. tT + jets (in jet bins)
  • study tTbB, scale/shower uncertainties, large differences between generators?
  • non-global observables, colour correlations

resonance aware matching (tT)

scale choices

  • LH Accord for scale variations? [discussion on: Thu June 8th, 09h00-10h30]
  • test case e.g. jet-veto cross section in Drell-Yan (+ N jets)


  • tensions within exp. data sets
  • theory uncertainties

EW corrections [discussion on: Fri June 9th, 16h30-18h00]

  • automation
  • renormalization
  • treatment of resonances
  • democratic clustering
  • additive/multiplicative
  • scale choice


  • comparison of IR subtraction schemes [discussion on: Wed June 7th, 10h30-12h30]
  • Ntuples, grids, non-author use (also for NLO use) [discussion on: Thu June 8th, 14h00-15h30]
  • standards for public multi-loop results (e.g. Loopedia) [discussion on: Fri June 9th, 14h00-16h00]


  • simplified template cross sections (STXS Higgs)(also fiducial/differential cross sections) ( wiki )
  • boosted H → bB
  • H differential
  • t/b mass effects
  • (N)NLO di-Higgs, gg → ZH
  • H total XS
  • off-shell Higgs
  • questions in VBF

SM backgrounds for DM searches (V+jets)

  • ratio Z/gamma, Z/W [discussion on: Fri June 9th, 09h00-10h30]
  • VH (H→bb), correlated scale variations
  • tT+gamma/Z

4-dim methods

wishlist update

Vector boson scattering

  • LO vs NLO, MC uncertainties, connection to VBF

List of brainstorming session June 15


  • Long-Lived Particles
  • How to use Correlation information
  • Fastsim vs smearing?
  • Simplified Likelyhood framework
  • Long-Lived Particles
  • Making analysis easier to recast?
  • Analysis description accord

Long-Lived Particles

  • Simplified Models
  • Zoology
  • Displaced vertices and baryogensis
  • Displaced tracks


  • Multiplet structure, LHC e+e-, gravitational waves
  • ggH at high pT
  • Couplings
  • Interference
  • Long Lived particles from Higgs
  • Light (< 100 GeV) Scalars (Higgs)
    • new variables
  • Data interpretation
  • BSM Higgs new signals, exotic decays
  • EFT
  • Di-Higgs
  • BSM Impact
  • EW phase-transition, baryogenesis
  • Couplings to light fermions

Dark Matter

  • New Models/Portals and LHC signatures
  • heavy flavour signatures
  • New searches
  • “Dark” parton showers


  • Low MET
  • RPV
  • High multiplicity

Lepton non-universality

  • Leptoquarks
  • other?
  • SM explanations
  • Links to DM and g-2



  • Vector-like quarks missing signatures
  • Missing resonance signals
  • Radion production @LHC
  • New models in MC?
  • Clockwork
  • Naturalness
    • Neutral Naturalness
  • EFT
    • NLO Tools
  • Strong Dynamics
    • Composite Higgs
  • BSM in top quark physics
  • LHC and flavour in New Physics
  • CP violation
  • Light particles
  • Beyond 14 TeV
    • New pheno

Preliminary lists (before start of the workshop)

MC and Tools

- (from ER,SP,VC) -

  • pt_Z at medium-large pt: few percent precision might require assessing impact of NP corrections; MC study ?
  • subleading-log effects in parton showering: find the best variables to test them, and motivate an experimental analysis?
  • NNLO+PS: how well do these tools work in regions where logs are large?
  • Matching/merging uncertainties in jet substructure analysis: impact on jet-substructure tool performance
  • Resonance-aware matching schemes: a comparison could be instructive at this point, possibly in the context of m_top measurements. [can use this study to finally promote the use of the (already existing) LHE-to-PS modern interface capable for example to handle multiple veto-scales]
  • A guideline for assessing uncertainties in NLO+PS matching: is this realistic? Can we find a balance between being fully conservative and its opposite?
  • EW showers vs. EW corrections at fixed-order: a dedicated comparison?
  • g → bbar , g→ ccbar

-(from JH)

  • followup on Higgs+jets study from LH2015
    • new study with inclusive jets
    • do parton showers have an impact on inclusive jet cross sections?
    • if all PS do not have a similar behavior, then why
  • do we understand in detail variations between various parton showers starting with as similar parameters as possible
    • can we benchmark “true” uncertainties
  • comparison of jet shapes at NLO/NNLO, PS and ME+PS
  • what is the role of UE when jet area subtraction is universally used


NNLO (from GH)
  • status wishlist
  • to which extent is automation possible?
  • availabitity to non-authors
  • scale choices
  • power corrections
  • methods for IR subtractions, e.g. pro's and con's of N-Jettiness
  • NNLO+PS (see above)
NNLO (additions from JH)
  • scale choices at NLO and NNLO
  • how “universal” (/“good”) is HT/2
  • scale choices for complex final states
  • comparison of power corrections for H+jet to W/Z+jet
NLO EW corrections (from SK)
  • status wishlist
  • combination with (N)NLO QCD results (additive, multiplicative)
  • inclusion of corrections beyond NLO (multiphoton emission, NLL Sudakov approximation of leading NNLO EW effects)
  • uncertainty estimates
  • treatment of resolved real-radiation photons (fully inclusive, vetoes)
  • public availability
mixed QCD-EW corrections
  • how to make use of NNLO results
PDFs (additions from JH)
  • inclusion of scale uncertainties
  • scale choice for inclusive jets (pTjet vs pTjetmax)
  • impact of new processes at NNLO (tT, photon+jet, dijet,W/Z+jet)
  • dealing with disagreements between observables/experiments
  • isolation for photons at NNLO
future colliders
ME+PS (from KT)
  • NLO+PS can (yet) fully replace the usage of LO+PS in physics analyses ? [practical issues to be discussed]
  • Dealing with the large fraction of negative weights
  • LO+PS reweighed to NLO+PS, how to (not) do this for specific candles (Z/γ, W)
  • scale variations/choices and their interpretation as uncertainties
  • VBF (V)V+2j with (N)LO+PS, QCD-EW interference and ME+PS matching, VBF signal definition
  • photon+jets and matching with QED/QCD showers, QCD/EW corrections
Modelling of W and Z/γ at high, medium and low PT (from KT)
  • LO+PS, NLO+PS, EW corrections on NLO+PS, NNLO+NNLL+PS, NLO QCD+EW + PS
  • low/medium PT what combination(s) to use for precision measurements and uncertainty envelopes
  • high PT and QCD+EW corrections
  • QCD/QED shower corrections + uncertainties at low/medium/high
  • resummation
Jet Physics (core dump from Jesse)
  • Closing the loop on quark/quark tagging
    • From the LH 2015 parton shower comparison study…
    • …to a concrete plan of action for LHC jet shape measurements
    • Improved PDF constraints from quark/gluon tagging
  • “Deep learning” meets “deep thinking”
    • Interface of machine learning and analytic calculations
    • Multi-category classification
    • Physics-inspired network design
  • Jet substructure for tagging
    • Interplay of jet radius, jet grooming, and jet discriminants
    • Tagging longitudinal versus transverse W/Z bosons
    • Impact of soft QCD (underlying event) and pileup
  • Groomed jets for precision physics
    • Top mass determination
    • alpha_s extraction from substructure
  • Jets and heavy flavor
    • Color flow/dead cone in top quarks
    • Jet substructure of b/c-tagged jets, gluon splitting to heavy flavor
    • Charmonium polarization in identified jets
  • Heavy ion physics
    • Jet shapes in medium
    • Probe quark/gluon plasma with boosted objects


  • “The Lifetime Frontier at the LHC”: Common language/signature space for displaced vertices.
  • “Beyond Missing Energy”: Do we have full coverage (if such a thing can be well-defined ) of BSM signatures which do not involve MET? E.g. R-parity violating SUSY, …
  • “Multiple unknowns”: most searches hunt for one new particle (+ MET in SUSY). How difficult is it to expand to multiple unknown particles? Does this add a lot of phase space coverage?
  • ' Beyond ATLAS and CMS': BSM at LHCb (and even ALICE). What more can be done with LHCb? Can we find BSM in forward/diffractive physics at all?
  • Colliders and multi-component dark matter
  • Of course, new ideas or new features from old ideas are always welcome!

BMS tools and MC (from LP, FM,PR)

  • EFT top/Higgs : basis, NLO corrections, applications…
  • Dark Matter specific tools: current challenges for s-channel/t-channel simplified models. NLO?
  • Recasting/presenting experimental results
  • Simplified Models
  • MC comparisons in BMS phase spaces (in overlap with SM session)
  • Boosted SM objects as probes for BSM searches (in overlap with SM session)

Higgs Physics

  • Heavy flavor modeling (in the context of ttH, overlap with MC and tools)
  • Quark-mass effects in inclusive and exclusive distributions (H+(N)j, ZH, HH)
  • Simplified template cross sections
    • Status of measurements and review of experience with stage 1 STXS
    • Development towards a more concrete proposal of stage 2
    • Theoretical uncertainties (including correlations)
  • Residual uncertainties in fiducial and differential cross section measurements
  • Complementarity between non-standard (SUSY) Higgs searches and precision H measurements
  • Higgs self coupling
  • Probing CP violation in the Higgs couplings
  • What are the holes in the searches for additional non-standard heavy Higgs bosons (H→ tt? what are the possible strategies?)
  • Searches for very light (ms < mh) scalar particles. Why (theory)? where we are, and where we can be in the future (experiment)?
  • Exotic decays of the 125 GeV Higgs. Which decay channels are not covered?
  • Pseudo observables and effective theories
  • Global picture of naturalness after run1/ first half run2?
  • Relaxion
  • High-energy versus high precision in Higgs physics?
2017/topics.txt · Last modified: 2017/06/15 15:31 by peter.richardson