RRT: BSM & Dark Matter (collider & beyond)

Thursday 10 Jul 2025, 15:00 → 15:59 Europe/Zurich

https://desy.zoom.us/j/69434264047

Meeting ID: 694 3426 4047
Passcode: 314159

15:00 → 15:55 What is missing in the PPG’s representation of the LC BSM / Dark physics case?

Speaker: All

Notes from meeting:

• Two categories of problem:
   - LC lines missing in plots that have been chosen
   - choice of plots tends to play down e+e- and particularly high energies
• We agree that 3TeV CLIC results should be included - briefing book should reflect complete state of scientific knowledge.
• From Rebeca's talk
  https://agenda.infn.it/event/44943/timetable/#20250626.detailed
• slide 5, Y-Universal Z' - where does LCF 500 line come from? - are luminosities correct for LC lines?  Should be updated with latest EFT fit, and 550.  (Roberto)
• slide 6, Le-Lmu - choice of model is surprising (but FCC-ee published paper in March). The "HET mono-gamma" is supposed to be a LC study projected on to this model; only 250.  But there is a full simulation study at 500GeV, also extrapolated to 1TeV, and CLIC also has a mono-photon study at 3TeV.  (Filip has UFO from Roberto, can have results in muon-gamma channel in a few weeks.)  Need to check where 4-fermion lines come from (final state?  contact interaction?), but strange that there is no LC line between FCC-ee and MuC 10TeV.
  Filip will try to collect mono-photon results.
  Jenny will look for 500GeV full sim study.
• slide 8, composite Higgs - LCF500 to be updated to 550
  slide 9, composite Higgs - 3TeV missing CLIC study is http://arxiv.org/abs/arXiv:1812.02093 Fig 35
• slide 10, RG-improved
  We think these are very simplified models; need to understand assumptions.
  Not clear what LCF means - Z-pole? CoM energies should be given
  CLIC study is http://arxiv.org/abs/arXiv:1812.02093 Fig 35, 36, 37
  Roman will dig deeper into this one.
• slide 12, real scalar singlet
  All LCs missing
  indirect constraints come from Higgs couplings fit, should be added for all LCs
  CLIC has resonant search, should be added
• slide 13 Higgs potential
  CLIC is missing.  LCF should give CoM energies.
  Sven/Georg should take the lead on this one
• slide 14 first-order phase transition
  Georg should comment.  Narrow correlation is not seen beyond Leading Order?
  LCF energies should be given.
• slide 15 first-order phase transition
  No lines at all for e+e- ?
  Was this in Shinya's talk from January?
• slide 17 wino, and slide 18 higgsino
  LCF 250, 550 should be added
  CLIC 3TeV should be added, http://arxiv.org/abs/arXiv:1812.02093 Fig 74
  Should be made clear that disappearing track results are much more model-dependent than the rest
• slide 20 - leptoquarks
  Should the models be more general?
  Theorists may want to comment.
• slide 21 flavour deconstructed models
  LCs have many Z' limits -- either they are missing, or the model here is particularly carefully chosen
  Should be as good as FCCee ee->ff, and polarisation could gain
  Perhaps Juergen could have a deeper look?
• slide 24 SUSY etc
  Mikael will take a closer look
  Sleptons should be added
• slide 25 top partners
  what constraints would come indirectly?
• slide 27 dark photons
  CEPC line is old theory estimate that is wrong
  FCC-ee may come from the same source?
  Mikael may be able to do a simple rescaling of LCF results to higher energies
  Beam dump area of plot - e+e- colliders are completely missing (Ivo)
• slide 30 HNL
  should include lines from Juergen/Filip/Krzystof's study
  
  
  
  
• NEXT steps:
  • Jenny notifies “scenario responsibles” not present
  • each “scenario responsibles” collects immediate comments by the weekend
  • Jenny provides overleaf skeleton, "scenario responsibles” there topics
  • first snapshot to PPG early next week with straight-forward comments
  • prepare more comprehensive view as well => updated dedicated note AND LCVision-Generic document 
    
    
• comment&question by Mikael: 
  

  I have a comment and a question on the plot on dark photons that you showed in your presentation on Monday (slide 6, and slide 11):

  You say that the curve for CEPC comes from Karliner &al (arxiv:2207.06307). This result is simply *wrong* - it is based on a much too naive view on how this kind of signal can be measured in any kind of collider detector, details in the ECFA-HEP report CERN-2025-005 (arXiv:2506.15390) p. 234-236. The curve should not be shown - CEPC could be asked to give an update.

  The question is how you did the extrapolation of LHC to HL-LHC (and FCC-hh)? I see a factor about 3 between LHC and HL-LHC, which i find surprisingly much. LHC to HL-LHC would mean ~10 more statistics, so I would expect the cross-section limit would be sqrt(10) ~ 3 times better, and since the cross-section goes with epsilon^2, the epsilon limit would be the square-root of that, so only about 1.8, not 3. Or am I missing missing something?

 

• comments by Lucie
  CERN-2018-009-M stands for the CLIC yellow report on the CLIC Potential for New Physics:    http://arxiv.org/abs/arXiv:1812.02093

 

• • Slide 6: Le-Lmu: LCF and CLIC are missing.

• • Slide 9: Compositeness: CLIC 3 TeV is missing. The corresponding study is documented in  CERN-2018-009-M

• • Slide 10: RG: CLIC is missing. For LCF a label on the used CoM energies is missing.  In general the plot is problematic; cannot match colours with facilities.

• • Slide 12: Scalar singlet: All Linear Colliders are missing. A CLIC study exists, documented in CERN-2018-009-M.
  • Slide 13: shape of Higgs potential: CLIC is missing. For LCF a label on the used CoM energies is missing. 

• • Slide 14: Scalar singlet: CLIC is missing. For LCF a label on the used CoM energies is missing. 

• • Slide 15: Electroweak Phase Transition:  Linear Colliders are missing.

• • Slides 17/18: Wino and Higgsino: LCF is missing. CLIC 380 and 1500 are shown. As MuCol at 3 TeV and 10 TeV is shown, it makes sense to add CLIC 3 TeV as well. A study exists for CLIC in CERN-2018-009-M (fig. 74)

• • Slides 20/21: Flavour: LCF and CLIC are missing, but MuCol and 3 TeV and 10 TeV is shown, which seems inconsistent.
    (CERN-2018-009-M addresses flavour issues for CLIC, but I see no overlap with the subjects in Rebeca’s talk)

• • Slide 27: Dark Photon: Very many facilities are shown in the plot, but LCF and CLIC are missing.

• • Slide 28: Dark Scalar/Higgs: LCF and CLIC are missing. FCC-ee curve is bizarre => looks like work-in-progress

• • Slide 29/30: ALP and HNL: LCF(250) is shown, but CLIC is missing.