1. 1 A.De Roeck CERN Amsterdam, April 2003 e-e-, gamma-gamma and e-gamma options for a Linear Collider

2. 2 In this study Gamma-gamma and e-gamma option –Working group on gamma-gamma/e-gamma collider technology K. Moenig and V. Telnov –Working group on gamma-gamma physics M. Kraemer, M. Krawczyk, S. Maxfield, ADR, (S. Soldner- Rembold) 4+2 meetings during this study During ECFA/DESY, integrated with other physics groups/ worked well! Many new results e-e- option –No new studies in the context of this workshop/ 2 meetings St Malo/Amsterdam C. Heusch Will remind some key issues based on Snowmass/Jeju reports

3. 3 e-e-option Advantages of e-e-: Large polarization for both beams: e L,e R Exotic quantum numbers (H -- ) Larger sensitivity in some processes Some very clean processes No s-channel, lower luminosity Non-Commutative QED Sensitivity to contact interactions …Majorana neutrinos

4. 4 e-e- option Higgs production Supersymmetry CP viol. phases But: No detector simulation, IR, beamstrahlung, selectron width…

5. 5 e-e- option Parameters (Snowmass 2001) Study for TESLA (S. Schreiber) Luminosity 5-(10)10 33 cm -2 s -1 L e-e- = 1/6 –(1/3) L e+e- Stability ~OK with intra-train feedback system

6. 6 e-e- option Future control room at the FLC?? No major changes required in IP or accelerator e-e- is the option which will be most easily to realize (for TESLA) Has to be kept on the roadmap S. Schreiber

7. 7 Gamma-gamma and e-gamma Compton backscattering on laser photons  Needs second interaction point  Needs crossing angle  Peaked but smeared spectrum Hence: needs extra effort Is it worthwile? Jeju panel discusion: Yes! Examples of advantages  Higher cross sections for charg. particles  Different J PC state than in e+e-  Higgs s-channel produced  Higher mass reach in some scenarios  CP analysis opportunities  Can test precisely couplings to photons…

8. 8 Gamma-gamma and e-gamma TESLA-TDR/ PLC workshop Hamburg 2000 Golden processes identified  Starting point in Krakow Only light Higgs  bb and QCD processes simulated (simplified) This study: Level of detail in  as good as in e+e- –SIMDET simulation for more golden processes H  WW, ZZ, Heavy MSSM H & A, WW production, Susy –Cross checks/elaborate for key process Higgs  bb –Further opportunities: CP studies, Extra Dimensions, NC QED,.. –Real luminosity spectra/polarization used (CIRCE, CompAZ) –B search using ZVTOP –Adding overlap events –QCD backgrounds in NLO –QCD Monte Carlo tuning to existing data Direct contact & exchange with the US studies/exchange tools

9. 9 Gamma-gamma and e-gamma Backgrounds and Luminosity –Luminosity/polarisation measurement (& corresponding syst.) –Background studies (pairs, photons, neutrons) –Evaluate design of IP/Mask/vertex detectors Technology –R&D efforts in Europe and the US

10. 10 Golden Processes hep-ph/0103090 Higgs SUSY Tril/quart. Top QCD T D R J Being done or ready: should be ready for the writeup J promised N O W

11. 11 Golden Processes Added at/since the Krakow meeting: Non-commutative QED e  for ED’s Light gravitinos Radions Gluino production H  (US groups) H  H+H- (US groups) CP analyses in the Higgs sector More (as yet uncovered/lower priority at present) e  e* Leptoquarks Strong WW scattering e  eH As always: still room for volunteers (next workshop)

12. 12 Gamma-gamma and e-gamma Information on lumi spectra, special SIMDET version, background… On our group web page…

13. 13 Luminosity Spectra Luminosities files with PHOCOL (V. Telnov) Can be used via CIRCE (T. Ohl) Analytical approximation COMPAZ (A. Zarnecki) TDR parameters

14. 14 Luminosity Measurement Proposals –ee  ee (  ) / not for J=0 –ee  ee  (  ) –ee  4 leptons Precision ~0.1% (stat) For Higgs (J=0) e.g. ee  ee  For e  collisions - e   e  - e   eee Moenig,Marfin,Telnov

15. 15 Monte Carlos & Tuning Amegic & Wing SHERPA Generator (F. Kraus et al.) Tuning of the Monte Carlo models via JETWEB (M. Wing) A tune for LC  studies has been produced Resolved Direct

16. 16 Background studies backgrounds studied for TESLA IP layout Study beam related background  # of QCD events overlapping now under control ( 1 evt@ 200 GeV and 2.5 evts @500 GeV). All groups agree (D. Asner, ADR, Telnov, Warsaw)  # of hits in the layers of the pixel detector per bunch crossing  Incoherent pair production: essentially the same as for e+e-  Coherent pair production: High! but ok, similar to e+e-  same vertex detector as for e+e- (Moenig,Sekaric)  Neutrons? Probably ok (V. Telnov) Moenig et al 1st layer 2nd layer…

17. 17 Background studies Moenig,Sekaric New: two-mask design Still being optimized Backg  /bx incoh/coh From outer mask 2.10 3 /10 4 Tracks in TPC 10 3 /2.10 3 Hits in vtx 368/20 Similar as in e+e- IP with present mask design Improves background by factor 2-3

18. 18 QCD To be used in the Monte Carlo programs QCD had been mostly studied --at detector level-- for the TDR Not revisited this time Exceptions (using new data)  Total  cross section parametrizations (Kwiecinski, Motyka,Timneanu) & (Pancheri, Grau, Godbole, ADR)  Structure functions PDFs (Krawczyk et al.)

19. 19 Higgs Heralded as THE key measurement for the gamma-gamma option From the TDR (Jikia, Soldner-Rembold) This workshop –Study H  bb, with realistic spectra, background, B-tagging efficiency,… –Study H  WW,ZZ –Study model separation power –Study spin of Higgs in H  WW,ZZ –Study CP properties of the Higgs –Study MSSM Higgs (H,A): extend e+e- reach –Study of the Charged Higgs (US) 250 350 10 3

20. 20 Using NLO backgrounds (Jikia…) Next question: Systematics…?? SM Higgs analyses 1 year/84 fb -1 P. Niezurawski Corrected inv. mass

21. 21 SM Higgs Analysis Analysis of a second group (Zeuthen) –Taking into account the QCD radiative corrections to the background process (Pythia + NLO Xsec.) through a reweighting procedure. –Adopting a b-quark tagging algorithm based on a neural network. A. Rosca = 1.9%

22. 22 SM Higgs: H  WW,ZZ Simultaneous determination of the Higgs Boson width and phase H  WW and H  ZZ measurements (full detector simulation)  /  = 3-10% M H < 350 GeV A. Zarnecki

23. 23 SM Higgs Analysis 120130140150160 1.81.92.23.06.8 M H  bb (GeV)  /  Warsaw group Different masses 2HDM SM-like versus SM (Ginzburg et al.)

24. 24 MSSM H/A Higgs Extend the detailed analysis to H/A  bb P. Niezurawski One year running and  s  500 GeV A 0 detectable for M A > 300 GeV beyond the e+e- reach

25. 25 MSSM H/A Higgs D.Asner/J.Gunion (LCWS02)  Extends e+e- reach  Need few years to close the LHC wedge European study in progress Study for a e+e- collider at 630 GeV e+e- 

26. 26 Angular distributions in  h  ZZ  lljj and  h  WW  4j D. Miller et al. hep-ph/0210077  Higgs spin and parity Detector effects are large, but sensitivity left  A. Zarnecki

27. 27 CP studies via  tt R. Godbole et al. hep-ph/021136 & LCWS02 Exciting possibility to analyse CP structure of the scalar Construct combined asymmetries from intial lepton polarization and decay lepton charge Done with Compton spectra Using COMPAZ reduces sensitivity with factor 2 Needs detector simulation

28. 28 real /parasitic E e  = 450 GeV ∫L  t=110 fb -1 E  = 400 GeV ∫L  t=110 fb -1 E ee = 500 GeV ∫L  t=500 fb -1 LL0.1%   ·10 -4 10 / (9.9)  6.7 3.1   ·10 -4 15 / 22/ (2.6)  6.0 4.3 sensitivity ~ proportional to the momentum of the particles involved in the triple gauge boson vertex Sekaric, Moenig Bosovic, Anipko Includes detector simulation/3D fits Studies starting for quartic couplings in  WW and  WWZ I Marfin Use of optimal variables F. Nagel et al. Study  WW e  W Triple Gauge Couplings

29. 29 TGC analysis with optimal obs. Nagel,Nachtmann, Pospischil Fixed photon beam energy/ No detector simulation Comparison with e+e-? New developments…

30. 30 Extra Dimensions  tt ADD type extra dimensions Sensitivity to mass M s Ideal Compton spectrum COMPAZ spectrum P. Poulose Realism reduces sensitivity: M s =1.7 TeV to 1.4 TeV SM+2  SM-2   s ee = 500 GeV =+1 =-1 MsMs MsMs

31. 31 Supersymmetry Several analyses starting  charginos  squarks e  slepton neutralino Will be pursued up to the detector level E.g. Kraus, Wengler Theoretical studies:  gluinos Interesting but needs simulation Klasen, Berge

32. 32 Technology Photon collider IP introduces new challenges –Laser –Optics –Stability & control in the IP (1nm?) /length control in cavity –Extraction line… Both Europe & US groups have and R&D effort. –Europe: use a cavity to reduce laser power –US: full power laser design US: laser commissioning 20 J pulses at 10 Hz / Full power next year –interferometery for alignment –½ size focusing optics setup in lab –beam-beam deflection feedback system study –PC testbed at SLAC? Proposal under preparation Europe : study cavitiy option –Make 1:9 size test cavity? Wait for funding/technology decision? Funding is an issue to continue R&D!

33. 33 Interferometric Alignment System Testbed at LLNL Half-scale prototype of optics / alignment system to test mirror quality and alignment scheme –Optics and laser interferometer currently installed J. Gronberg

34. 34  Engineering Test Facility at SLC Revive SLC and install beampipe with optics to produce  luminosity Beam Energy DR  x,y (m-rad) FF  x,y (m-rad)  x /  y  z  x,y N  30 GeV 1100 / 50  8 / 0.1 mm 0.1 – 1.0 mm 1500/55nm 6.0E9

35. 35 G. Klemz New proposal

36. 36 Conclusions Lot of activity on gamma-gamma during this workshop series –Good balance found between gamma-gamma specific meetings and integration with the other groups Good progress on tools/background etc, for gamma-gamma studies Many detailed studies –The light Higgs results confirmed and extended    /   ~ 2% –Higgs channels in WW,ZZ studied    /   ~ 3-10% –H/A study confirms reach for high masses, beyond e+e- –CP, Higgs spin etc  studies starting –Detailed study of the TGCs  measurement competitive with e+e- –First results on SUSY and Extra Dimensions/alternatives  explore during the continuation of the workshop Confirms  /e  as an exciting option for a LC ! Progress also with hardware plans (PC testbed/Berlin studies) Big thanks to all participants, particularly the Warsaw and Zeuthen Groups