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Physics Options Overview for the ILC

Explore the physics potential beyond the Standard Model at the ILC, understanding Electroweak Symmetry Breaking, and the importance of machine options for enhanced precision studies. Learn about the baseline ILC parameters and additional options for optimizing physics reach.

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Physics Options Overview for the ILC

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  1. Physics Options Overviewfor the ILC De Roeck CERN SLAC, MDI meeting, January 2005

  2. SM SUSY Physics Case for New High Energy Machines Understand the mechanism Electroweak Symmetry Breaking  What is the origin of mass of the fundamental particles? Discover physics beyond the Standard Model Reminder: The Standard Model - tells us how but not why (contains 19 parameters!) 3 flavour families? Mass spectra? Hierarchy? - needs fine tuning of parameters to level of 10-30 ! - no unification of the forces at high energy If a Higgs field exists: - Supersymmetry - Extra space dimensions If there is no Higgs below ~ 700 GeV - Strong electroweak symmetry breaking around 1 TeV Other ideas: more gauge bosons/quark & lepton substructure, Little Higgs models… Most popular extensions these days

  3. The ILC • ILC world wide consensus for a baseline linear collider with a centre of mass energy up to 500 GeV and a luminosity above 1034cm-2s-1 • However the ILC will be much more • Its required flexibility/tunability in CMS energy, and additional options will greatly enhance its physics potential for precision EWSB studies, or disentangling the new physics • The baseline & options have been outlined in the document parameters for the linear collider •  Special studies and/or R&D for these options is required (and ongoing) •  We do not know for sure what path Nature has chosen, hence the priority and • importance these options will become clear with the data of the LHC and • first data of the ILC. •  The implications of these options on machine, MDI and detectors should • be taken into account –where possible - from the start.

  4. ILC Parameters & options • Baseline ILC • Minimum energy of 500 GeV, with int. luminosity of 500 fb-1 in the first 4 years • Scan energies between from LEP2 till new energy range: 200-500 GeV with a luminosity ~ s. Switch over should be quick (max 10% of data taking time) • Beam energy stability should be to less than 0.1%. • Electron beam polarization with at least 80% • Two interaction regions should be planned for • Should allow for calibration running at the Z (s = 90 GeV) • Upgrade: Energy upgrade up to ~ 1 TeV with high luminosity should be planned • Options beyond the baseline: enhance the physics reach • Running as an e-e- collider • Running as a e or  collider • Polarization of the positron beam • Running at Z0 with a luminosity of several 1033cm-2s-1 (GigaZ) • Running at WW mass threshold with a luminosity of a few times 1033cm-2s-1 • (not in the document) Extendability to multi-TeV?? Several years of intense physics studies have led to:       

  5. Interaction Regions • baseline recommendation for the ILC parameters for two interaction regions (KEK) November 04

  6. Interaction regions • How symmetric should these interaction regions be (for physics)? • High versus low energy IR? • Simultaneous or staged running? As an experimentalist on LEP, HERA, LHC I believe that • Both experiments will want to measure e+e- collisions at the maximum ILC energy • Both experiments will want to have data as soon as they are ready (even before) • Simultaneous like running will be preferred if not a technically nightmare and if the efficiency to collect good data is acceptable, especially at the start. (Moenig/Stahl: worry about polarization?) So I would not give up on that option (yet). • Ideally: experiments have a specialization. Eg. one may include gamma-gamma in its baseline design, or may optimize detector more for Z runs May help to decide on which experiment goes to what IR • Cost of 2nd interaction region? (~10%?)

  7. e-e- collisions Advantages of e-e-:  Large polarization for both beams: eL,eR Large polarization of the e- beam Work with fundamental fields of particles with well defined handiness Exotic quantum numbers (H--) Larger sensitivity in some processes Some very clean processes No s-channel, lower luminosity

  8. e-e- option Minkowski Higgs production Mass reconstructed from tagged electrons needs good forward detector coverage down to a few degrees Supersymmetry Heusch Thomas measurement of CP violating phases Note: before detector simulation, IR, beamstrahlung, selectron width…

  9. e-e-option Non-Commutative QED Sensitivity to contact interactions Hewett, Petriollo, Rizzo Barklow …Majorana neutrinos Heusch Minkowski …for equal luminosities

  10. e-e- option Parameters (Snowmass 2001) Study for TESLA (S. Schreiber) Luminosity 5-(10)•1033 cm-2 s-1 L e-e- = 1/6 –(1/3) L e+e- Stability ~OK with intra-train feedback system

  11. e-e- option • No ‘major’ changes • required in IP • or accelerator but • need to include • spent beam • kicker magnets? • feedback system • second e-source • … S. Schreiber e-e- is the option which should be easy to realize Has to be revisited during the MDI discussions to keep on the roadmap Clem Heusch’s dream: Future control room at the ILC??

  12. The photon collider option  and e option

  13. Gamma-gamma and e-gamma • Compton backscattering on laser photons • Peaked but smeared energy spectrum •  Highly polarised photon beams • However: needs extra effort • Is it worthwile? • Jeju LCWS02 panel discusion: Yes! • Examples of advantages • Higher cross sections for charg. particles • Different JPC state than in e+e- • Higgs s-channel produced! • Higher mass reach in some scenarios • Pure QED interaction (in e+e- also Z exchange) • Higher polarization of initial state (>80%/beam) •  CP analysis opportunities (linear  polarization…)

  14. Parameters for the TESLA design V. Telnov Since in  collisions the electron beams do not meet (and self-destroy) one can reach higher geometrical luminosities by focusing stronger and have a smaller emittance (round beams) than in e+e-/e-e- optics Only the high energy part is of interest for the luminosity! Both beams are e- z=W/2Ebeam

  15. Higgs SUSY EDs,… Trilin. coupl. Top QCD Golden Processes for a Photon Collider Added value to an e+e- collider Boos et al., hep-ph/0103090 ADR (ECFA/DESY) hep-ph/0311138

  16. Example: Higgs Krawczyk et al., Moenig et al. The precise measurement of the 2-photon width of the Higgs is very important. It is affected by all charged particles that can occur in the loop Very sensitive to new physics QCD bb in  suppression: V. Khoze,… New physics effects are few % to 10%

  17. Example: MSSM Higgses H,A Minimal Supersymmetric SM: 5 Higgses: h,H (CP even), A (CP odd) and H Krawczyk et al Photon collider only option to close the wedge for masses up to ~800GeV PC: Measurement of / to 10-20% (1 year running) e+e- collider: H,A produced in pairs, hence MA reach is see/2  collider: s-channel production, hence MA reach is 0.8•see

  18. SUSY example Extended reach for sleptons Watanabe et al. e+e-: reach is s/2 e: reach is 0.8s - M(LSP) Can extend the mass range by 100-200 GeV if LSP is light M(LSP) = 100 GeV

  19. The Photon Collider Option Special requirements for a Photon Collider at the ILC • Crossing angle between the beams should be O(25-30mrad), for the removal of the disrupted beams, (angle > disruption + Rquad/L ~0.01+6/400 ~ 0.025) • Product of horizontal and vertical emittance should be as small as possible to allow for high  luminosity • Final focus: as small as possible spot size at IR (reduce horizontal  function by order of magnitude compared to e+e-) • Beam dump: cannot deflect photon beam  narrow photon beam in a straight line from the IR • Modified detector in the region  < 100 mrad, including the vacuum pipe and vertex detector • Space needed for laser beam lines and housing Summary letter sent to the ISCLC in July 04, after LCWS04 Proposal of the PC study contact persons and workgroup convenors  Design the 2nd IR optimized for a PC, but keep full compatibility of the FFS to allow to run also in e+e- mode (horizontal  function). Detector to be designed to operate in both modes, with easy transition

  20. Interaction region Mask and laser optical paths designs K. Moenig et al. • Study of beam related background: • e+e- pairs, overlap events, neutrons • # of hits in the layers of pixel detector •  Incoherent pair production: essentially • the same as for e+e- • Coherent pair production: High! but ok, similar to e+e- (Moenig,Sekaric) •  same vertex detector as for e+e- •  Neutrons? Under study (V. Telnov)

  21. G. Klemz Optical cavity to store laser pulses (TESLA)

  22. Beam Dump Design V. Telnov See talk tomorrow Angular divergences of disrupted beams

  23. PC R&D • Photon collider IP introduces new challenges • Laser & Optics • Stability/control in IR (1nm), cavity length control, alignment, feedback… • Extraction line, beam dumps…  Opportunities also for university projects/contributions • Important to involve laser expert community (LLNL, others) • Some collaboration established but need intensifying • Hardware e.g. (reduced size) cavity or focus region needs to be tested • Suitable lasers (prototypes) need to be tested • Some related activities • LLNL plan to work on cavities to generate sufficient laser power for making a positron source via Compton scattering; Gain experience with high power issues, critical for PC lasers • Orsay: build a laser resonator for a polarimeter, as part of EuroTeV World wide organized R&D for this option is needed

  24. Polarized Positrons • Polarization of the electron beam in base-line program • Techniques have been already succesfully (SLC) • Allows to reduce background/enhance signal for s-channel processes • Allows e.g. for LR measurements in s-channel processes, single spin asymmetries, measurements of couplings… • Polarization of the positron beam • Techniques in R&D phase (helical undulator, Compton scattering) • Increases the effective polarization • Reduce the uncertainty of the polarization • By error propagation (factor 3-4) eg. for Pe-=80% and Pe+=-60%  Peff=95% Peff/Peff~1/3P/P • By using the Blondel scheme See K. Moeing talk

  25. Polarized Positrons: Physics Topic Examples • High precision analysis in the SM • Triple gauge couplings in e+e-Z • Anomalous couplings in e+e- W+W- • Transversely polarized beams in e+e- W+W-, graviton effects • GigaZ (see later) • Sensitivity to CP violation the SM • Revealing the structure of SUSY • Quantum numbers in e+e-  selectron pairs • Stop mixing angle in e+e-  stop pairs • Study of the chiral structure of the Gaugino/Higgsino sector •  polarization (large tan case) • CP phase determination in stau sector • Identification of extended susy scenarios • Enhancing reach for extra dimensions in e.g. e+e-G, etc, etc.. Report from the POWER group being released soon

  26. Polarized Positrons: Examples Test if the sparticles have the same chiral quantum numbers as their SM partners G. Moortgat-pick Disentangle from with polarized e+ U. Nauenberg et al Discovery: Look for kinematic edges in inclusive muon distribution ! WW background ! 

  27. Polarized Positrons: Examples ADD eeG cross section Z’ couplings from e+e-ff Background no polarization e+ polarization e+ and e- polar G. Wilson Casalbuoni et al. ADD effects in e+e-ff e+e-bb e+e-cc Transverse polarization PT=0.8 P’T=0.6 T. Rizzo cos cos

  28. Polarization and MDI • Polarimeters for longitudinal (and transverse) polarized beams • Polarimeters before and after the IR? • Polarimeter after the IR only possible with crossing angle (?) • Depolarization effects: so far expected to be in control for 0.5-1 TeV but is large for e.g. for CLIC • Redundancy is not a luxury for precision measurements so if we can have data to check, so much the better. But what can we really learn from this measurement? • Use also other physics processes to check, see talk of Klaus • Precision of the polarimeters 0.5-0.25% adequate for everything? • High statistics channels (Z’, TGCs) require O(0.1)% • GigaZ requires 10-4, needs polarized e+ (Blondel Method)

  29. GigaZ option • Measure to a precision of O(10-5) from left-right asymmetries • Z-lineshape: improve Z-width with a factor two, cross section ratios by a factor three ( factor two on  and a factor 3 on s) • Zbb couplings improved by factor 5-10 wrt. LEP • B-physics: Factor 10 improvement in Electro-weak b-quark physics possible, CP violation effects, rare B-decays (maybe need 1010 Zs) Luminosity ~ 51033cm-2s-1 at Z pole 109Zs in less than a year  100 x more statistics than LEP (1000x SLC for polarized studies) Imposes stringent requirement on the control of the beam energy and beam energy spread, polarization, luminosity precision, detector (b-tagging)…

  30. Measurement of sin2 • Stat. error with 109 Zs: ALR/ALR=4.10-5 (Pe-=80%,Pe+=0%) • Error from the polarization ALR/ALR= P/P • With positon polarization (Pe-=80%,Pe+=60%) • Gain a factor 3-4 with error propagation • Apply Blondel scheme • Need to understand polarization differences between the two helicity states to the level of 10-4. Need to take into account correlations between the polarizations of the two beams. Track time dependencies of the polarization.  Beam energy ALR/s = 2 10-2/GeV from Z interference need to know s ~ 1 MeV relative to the MZ (spectrometer with 10-5 relative precision)  Beamstrahlung: need to be controlled to a few % Challenging requirements!!

  31. Z-scan observables • If relative beam energy measurement of 10-5 can be reached then /=0.410-3 (compared to 0.910-3 at LEP) • Assume the selection efficiency for leptons to be improved by a factor 3 w.r.t. LEP detectors  improve the leptonic to the hadronic cross section ratio Rlep/Rlep=0.310-3 (1.210-3 at LEP) • With luminosity measurement improvements w.r.t LEP: improve the hadronic pole cross section 0  Beam energy spread should be kept below 0.1% and understood to the level of a few% for the 0 and  measurements  In principle both are in reach of the Bhabha acolinearity measurement. Improvements on line shape related quantities Z properties affected by new physics: e.g. Z’ like objects in hep-ph/0303107

  32. WW factory Revisiting the W mass  Threshold scan: a six point scan with 100 fb-1 (1 year) • Efficiencies and purities as at LEP • Beam polarization used to measure the background/enhance the signal • Need P/P < 0.25% • If polarized positrons are available, can use the Blondel scheme • Beam energy needs to be controlled to 510-5 between mZ and 2mW • Can reach a precision of 6 MeV on MW (compare: 15 MeV at the LHC) G. Wilson

  33. Multi-TeV collider • CLIC two beam acceleration presently thought to be only feasible way to multi-TeV region  CTF3 under construction/operation at CERN • MDI related issues to keep in mind if one plans for a facility that should be upgradable to a multi-TeV collider in future • crossing angle needed of ~20 mrad (multi-bunch kink stability; see tomorrow) • Present desing: Long collimator syst. (2 km on each side) and final focus (0.5 km) • Energy collimators most important. Fast kicker solution not applicable. Maybe rotating collimators … • Gentle bending to reduce SR & beam spot growth construct the linacs already under an angle of ~ 20 mrad • Internal geometry differences of the collimation system and final focus, allow for enough space in the tunnels (O(m))

  34. Multi-TeV physics: Examples MH=900 GeV New Z’ resonance Heavy Higgs ADD Extra Dimensions Supersymmetric particles: # of higgses, sleptons gauginos, squarks detected for benchmark scenarios (hep-ph/0306219) s=5 s=3 CLIC physics study CERN-2004-005 & hep-ph/0412251

  35. Importace of the Options: Eg. SUSY Supersymmetry: Study of benchmark point (SPS1a or B) From the document LHC/ILC complementarity hep-ph/0410364 To fully exploit the ILC potential and measure the new sparticle masses we need: e+e- up to 1 TeV, e-e-, polarized positrons (60% assumed here), and a PC to measure the heavy Higgses.. (H,A)…

  36. Summary • Additional options to the ILC will certainly increase the physics reach of the ILC. All have their merits Today we do not know which one of these will have the highest impact on the physics program • The options have consequences for the MDI With the WG4 recommendation it looks natural to suggest to study in detail the IR with large crossing angle (15-20) mrad is kept compatible for a PC option (or even multi-TeV) from the start What would we loose if the crossing has to be 25 mrad? • Affects small angle tagging efficiency of electrons from backgrounds SUSY: eg. reduced efficiency for stau’s in stau- degenerate mass scenarios (CDM studies). Perhaps affordable? • Some luminosity reduction • Are there additional technical risks? • Should include all options & their requirements in the MDI studies

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