1. 1 Higgs : keV precision and CP violation W. J. Murray RAL

2. 2 Talk overview Reminder of Muon Storage rings SM expectations: Higgs MSSM potential CP violation studies

3. 3 Reasons for muon collider Large  mass so small storage ring 10 -5 beam energy spread possible No beamstrahlung  Clean thresholds Energy known to 10 -6 via g-2 S-channel Higgs production, 40000 * electron equivalent This is a precision machine!

4. 4 Disadvantages of a muon collider Muon lifetime 2.2  s Electron decay background hard Beam preparation and cooling difficult Luminosity per amp vital 

5. 5     Collider Overview one conceptual layout of a muon collider

6. 6 Goal: 10E21 muons/year CERN muon neutrino source Recycled LEP RF Or a Higgs ring

7. 7 Proton Driver requirements Maximum muon intensity –Maximum proton power (1-10+MW ) Short bunch length (~1ns) –High phase-space density Optimization of proton energy not final –Experiment to measure pion yields (HARP) –e.g. 250uA @2GeV Linac + Accumulator ring

8. 8 The SPL on the CERN site

9. 9 Target and pion collection A number of ideas are under consideration which in principle should allow a beam power on target power of up to 4 MW. The crucial problems are mechanical movements in high magnet fields, heat transfer, material stress, radiation damage and radioactivity confinement. A liquid metal (mercury) jet target may be the easiest way to meet all criteria simultaneously

10. 10 Target

11. 11 Decay &  capture  to  decay in long 2T solenoid Gives momentum-time correlation Use in phase-rotation RF system –long bunch, reduced p spread ~100MeV

12. 12 Ionization Cooling Principle Loss of transverse momentum in absorber: Changes transverse emittance:  Re-acceleration does not change normalized emittance)

13. 13 Heating by multiple scattering Multiple Scattering in material increases rms emittance  Combining cooling and heating:

14. 14 Ionization Cooling Considerations Want materials with small multiple scattering (large L R ), but relatively large dE/ds, density (  ) Want small  * at absorbers => strong focusing - equilibrium emittances (/  *) smallest for low-Z materials

15. 15 Ring Cooler ??? Ring Cooler can provide simultaneous transverse and longitudinal cooling Major difficulty in all cases is injection and extraction- no room for fast kickers … 6-D cooling by ~100  in ~20 turns appears possible…

16. 16 Final-stage Li-lens Cooler V. Balbekov designed a 5-lens system which provides cooling down to Collider parameters (PAC 1999 proceedings) Simulation results: 5-cell Li-lens system cools transversely from  t,N = 0.1cm to 0.015 cm

17. 17 What cooling has been designed? Transverse and longitudinal cooling New helical and ring cooling schemes promising From R.Fernow

18. 18 Storage Ring For a collider smallest possible ring –3TeV in 6km –115GeV in 350m ~1000 turns, energy independent –Proportional to Magnetic field of dipoles But dipoles need to cope with decay electrons  `open’ design

19. 19 Parameters of    - colliders

20. 20 Energy calibration Muons are polarized Precess Alters electron energy spectrum Extract E to 1 in 10 6  E measured from amplitude reduction

21. 21    - Detector Geometry Tungsten nose at 20 o –Luminosity with high-angle event Small window on beam Detectors at 5cm Beta-Heitler 1ns out of time?

22. 22 Scan of Higgs resonance 150pb -1 needed to locate Higgs, if 100MeV error Width error 1MeV after 2 years Mass error 100’s keV! Best argument for machine? Higgs found first! 0.003% beam error - costs lumi.

23. 23 Is the Higgs width interesting YES!

24. 24 Does the width test the MSSM? LHC + LC  100pb -1  10fb -1

25. 25 What do we learn of MSSM? Blow up FPMC region Just from scan of h!

26. 26 Accuracy versus Higgs mass Higgs  in bb and WW states Error from 300pb -1 115GeV is optimal Favours region of MSSM!

27. 27 No-lose theorem of MSSM If  h is suppressed Then  H,A is enhanced!

28. 28 Scan of h and A of MSSM Only machine which could separate these? Observe 2 particles Measure Br’s, masses, CP observables Thousands of events per year

29. 29 CP violation of light Higgs Transverse polarisation CP asymmetries lightest Higgs boson Down type Up type

30. 30 H/A in presence of CP violation Precise beam energy control Cross section of order 1pb Measurable with moderate polarisation –As given naturally Solid –  =0 Dashed-  =90 Asakawa, Choi & Lee, Phys. Rev. D62 (2000) 115005

31. 31 What if M h nowhere near 115? LHC might discover M H =600 –EW fits misleading! This is possible, for example with –Two doublets, – m h ~m H ~m H + ~600GeV –m A ~100GeV – unobserved @ LHC/500GeV NLC –Splitting of H 0 /H + may hide effects Gunion: hep-ph/0012199 Such a scenario would mandate  collider Could find A by auto-scan or direct scan

32. 32 Conclusions: There is a tremendous Physics case – Higgs factory – MSSM CP potential Work on  e advances technology     Precision physics is excellent! Need to know m H first