Theory Sessions -- Summary

1. Theory Sessions -- Summary Outstanding Plenary Talks: Physics at a TeV Lepton Collider Estia Eichten Physics Benchmarks Marco Battaglia Physics Issues John Gunion SUSY and Dark Matter at an MC Paddy Fox Outstanding working group talks: Physics Cases for Muon Colliders Tao Han Strong Dynamics at a Muon Collider Adam Martin The A0 – H0 Resonances Dave Cline Comments on Dark Matter at an MC Graham Kribs A Light Dilaton at an MC Yang Bai QCD Issues at Lepton Colliders Gerban Stavenga Strong Dynamics and the Lattice George Fleming (Some of the) Particle Physics on the way to the MC Andre deGouvea

2. Discussion: Physics Benchmarks for Lepton Colliders Purpose of Benchmarks: Probe efficacy of Muon Collider (cone angle, bkgnds, pol., L , dE/E , E) Compare and contrast e+e- and m+m- machines: Energy reach? Luminosity? polarization? dE/E ? Test physics discovery potential against background and geometry issues Benchmarks should be robust as the new physics emerges at LHC Provide useful issues for detector simulation studies e.g., how is forward WW fusion impacted by cone blockout? how is reconstruction affected by polarization, dE/E?

3. The top six: Process Observables Experimental Theoretical Strategy considerations considerations Z’ M, G energy scale = M ? coupling strength first priority if couplings beam energy resolution L – R chiral confirmed at LHC; final states initial state polarization ? compelling models may enable low-L cone size machine Contact Terms WW fusion M beam energy coupling strength High priority couplings initial state polarization strong dynamics if no low mass states? cone size ! (broad TeV scale Higgs) Higgs at LHC SUSY/BSM many states beam energy resolution Mainstream theory Simply depends select processes decay chains initial state polarization perturbative dynamics upon confirmation m’s, Br’s, s’s missing ET cone size MSSM or else? at LHC Dark Matter g or Z cms frame is known Very interesting High priority + missing ET initial state polarization? how powerful are limits? appears easy to do missing ET cone size Need the paper asap ! Higgs, MultiHiggs, H0-A0, scalar resonances, CP-violation etc.

4. Z’ Eichten, Gunion:

5. Z’ Comments • My personal view: This may the single most important issue governing the possibility of having a muon collider. It is also likely to be ruled in or out by LHC soon. If Z’ exists we can contemplate a low luminosity first MC (e.g., Neuffer’s talk) • Many Z’s to study; various final states, compelled in some models • Study dependence of sensitivity vs parameters, eg, G/M and Br’s. • Probes forward cone, energy, energy resolution, polarization

6. Contact Interactions Eichten:

7. Contact Interactions Comments: Contact interactions should be easy to treat fully and are potentially Illustrative of polarization (chiral contact terms), geometry (cone obstruction) and energy reach Issues. Some more theoretical work is needed here to compare muC with e+e-: • Include quasielastic ops with mu+mu -> light f + f • mu+mu -> top + top • mu + mu -> WW, ZZ, etc.

8. Fusion Processes Eichten, Gunion, Martin: Generally “X” is a broad heavy TC Higgs

9. Fusion Processes Comments: Fully simulate measurement of broad heavy TeV scale Higgs Probe energy reach and detector geometry (forward cone). List of candidate fusion processes? E.g. q qbar production

10. SUSY: is an Industry Standard in e+e- machine studies. Illustrate strength of polarization and energy resolution in reconstruction and physical parameter determination Battaglia, Gunion Han, Fox:

11. Battaglia:

12. Subset of processes may be particularly illustrative owing to complexity; e.g. Study advantage of small dE/E in mass determination from sharp kinematic edges: Study severity of forward cone obstruction

13. “Equivalent” Illustrative benchmark processes involving KK mode production: Assess effect of Beamstrahlung , initial state radiation

14. SUSY/BSM Comments: There is no standard SUSY model for this (as there was in ILC era). Generic SUSY and BSM models have illustrative value They offer rather well defined complex processes worthy of study. Industry standard. Strategy: we abstract generic sub-processes from these models and analyze them to thoroughly in both machines: (eg, and gaugino production) Can the sophisticated analysis software for e+e- be adapted to MC? Who will undertake this and when?

15. Fox, Kribs: Dark Matter at Colliders

16. Fox: (Z’s ?) “Dark Matter contact terms” with associated radiated gauge boson

17. Fox:

18. Dark Matter Comments: • Need to study and generate basic plots for high energy lepton colliders. We need this paper asap. • g + missing ET, and Z + missing ET !!! • High energy machine may produce the mediator. • Urgently needs a study; this is a sexy topic. • Giele & Stavenga to study radiative corrections relevant to lepton machines

19. Battaglia, Cline, Eichten, Gunion, Han: Higgs and MultiHiggs

20. Battaglia:

21. H0 A0 Resonances (Gunion, Han, Cline) Cline: possible observable CP-violation

22. Gunion:

23. Higgs and Multi-Higgs Comments: This is fairly well-defined within single and two doublet models

24. Other Important Discussions: New Strong Dynamics (Fleming, Martin) Muon Collider and QCD issues (Giele, Stavenga) Neutrinos and Muon Physics (de Gouvea) The Dilaton (Bai)