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

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

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

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

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

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. Linac + Accumulator ring

8 The SPL on the CERN site

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 Target

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

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

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 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 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 cm

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

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 Parameters of    - colliders

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

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 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 Is the Higgs width interesting YES!

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

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

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

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

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

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)

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 – LHC/500GeV NLC –Splitting of H 0 /H + may hide effects Gunion: hep-ph/ Such a scenario would mandate  collider Could find A by auto-scan or direct scan

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