Physics Opportunities and Experimental Techniques

1. The International Linear Collider Physics Opportunities and Experimental Techniques for the Next Large Scale Facility in Accelerator Particle Physics Marco Battaglia UC Berkeley and LBNL TASI, Boulder, June 2006

2. Higgs Sector Profile at ILC

3. The Higgs Profile and Physics beyond In models with extended Higgs sector, such as SUSY, Higgs couplings get shifted w.r.t. SM predictions: Precise BRs measurements determine the scale of extended sector:

4. Higgs/Radion mixing The Higgs Profile and Physics beyond In models with new particles mixing with the Higgs boson, branching fractions are modified, generally through the introduction of an additional (invisible) decay width; Models of extra dimensions stabilised by the Radion are characterised by potentially large changes to Higgs decay Branching fractions:

5. ILC Physics and Cosmology Dark Matter established as major component of the Universe: CMB determination of its relic density further confirmed by SNs and galaxy clusters; Additional astrophysical data manifest possible evidence of DM annihilation: EGRET data show excess of g emission in Inner Galaxy; WMAP data may show excess of synchrotron emission; Establishing the inter-relations between physics at the microscopic scale and phenomena at cosmological scale a major theme for the next decades.

6. Cosmology tells us that a significant fraction of the Universe mass consists of Dark Matter, but does not provide clues on its nature; Particle physics tells us that New Physics must exists at, or just beyond, the EW scale and new symmetries may result in new, stable particles; As LHC and ILC will access TeV scale, we have the opportunity to directly produce and precisely study microscopic properties of dark matter candidate particle and compare these data to what we are learning from satellite and, eventually, direct detection experiments. From WMAP determination of DM density and infer that DM particle mass should be O(100 GeV)

7. ILC Measurements Colliding elementary particles of well defined, tunable energy, quantum Numbers ILC will allow to study production and decay properties of SUSY particles up to kinematical threshold (~500 GeV); Direct access to weakly interacting SUSY particles; Masses determined to O(0.1%) from kinematics and threshold scans; Couplings and quantum numbers measured using decay properties and production cross sections with polarized beams. Geant 4simulation of heavy neutralino production in LDC detector

8. WIMP Dark Matter in cMSSM SUSY models analysis simplified within cMSSM: dimensionality of parameter space reduced by one (m1/21 m0): four regions emerge:

9. ILC-LHC Complementarity ILC precision and versatility crucial in extending discoveries, fully testing nature of physics and complete mapping of the new frontier first explored by the LHC:

10. ILC-LHC Complementarity SUSY offers interesting template for complementarity in new particles to be discovered at LHC and ILC, but also for higher sensitivity to Cosmology-motivated scenarios at edges of phase space:

11. Momentum End Points • In two body decay Esquark = Ebeam if pair produced, • escapes unobserved and energy of only particle left (q) can be related to mass difference (ratio) between squark particle and LSP : • Method originally introduced for squarks applies also to sleptons • and allows to • determine slepton mass once • known or determine relation between masses and get LSP mass if slepton can be independently measured; Emin Emax Accuracy limited by beamstrahlung, not dp/p.

12. Threshold Scan Determine signal cross section at threshold as function of centre-of-mass energy, fit data to extract mass and width of pair-produced particles; Accuracy on particle mass m S-wave process = b rise of cross section P-wave process = b3 rise of cross section Weak dependence of dm accuracy on nb. of scan points N, optimal scan with luminosity concentrated at 2 or 3 points

13. WIMP Dark Matter in cMSSM

14. Bulk Point LCC1

15. gaugino Masses tan b Heavy part of SUSY spectrum decouples from DM density determination: m squark Mass M(A) In bulk region DM density controlled by LSP annihilation to leptons via slepton exchange: need to determine LSP and slepton masses but also ensure no other mechanisms contribute.

16. A Run Plan

17. WIMP Dark Matter in cMSSM

18. Focus Point LCC2 Squarks Sleptons Heavy Higgses

19. DM density controlled by LSP annihilation to WW and ZZ, large mass splitting between gauginos and sfermions:

20. ILC Measurements at LCC2 Study of Focus Point at 0.5 TeV based on five main reactions: e+e- "c+1c-1, c+1c-2, c01c03, c02c03, c03c04 Determine mass differences from endpoint of ll and jj distributions and use kinematics to fix masses: Availability of polarised beams provides additional observables for establishing properties of gauginos; ll Inv. Mass (GeV) Alexander et al.

21. WIMP Dark Matter in cMSSM

22. co-Annihilation Point LCC3

23. DM density controlled by stau-LSP mass splitting and m: sensitivity to small DM depends on gg background rejection:

24. ILC Measurements at LCC3 At 0.5 TeV production of t1t1 and c1c2 resulting in tt Emissing final state; Determine M(t1) - M(c10) from distribution of M(j1j2Emissing) DM/M = 0.10 (stat.) Dutta, Kamon, SUSY05

25. Crucial to reject gg bkg ee "eett by low angle electron tagging: Very Fwd. calorimetric coverage controls minimumreachable DM:

26. WIMP Dark Matter in cMSSM

27. A0 Funnel Point LCC4

28. DM density controlled • by M(A)/2M(c), G(A), • requires intensive program of measurements from 0.35 TeV to 1.0 TeV:

29. ILC Measurements at 0.5 TeV Stau Threshold Scan Determine M(t1) and M(t1) - M(c10) from stau threshold scan and stau decays; Estimate G(A0) from precise determination of BR(h0"bb) at 0.35/0.5 TeV; M(j1j2Emissing)

30. ILC Measurements at 1 TeV Determine MA from reconstruction in 4-b jet events at 1 TeV; Apply 4C constraints and determine MA and GA from 5-par fit to Mjj spectrum using signal + quadratic background term: Determine M(c3)-M(c1) from Z energy distribution in c3 "c1 Z decaysin c3c2 events to fix m value; At LHC M(A) measurable to 2 GeV but difficult to control G(A) and m. M.B. hep-ph/0410123

31. Constraining tan b at 1 TeV Points at large tan b, such as LCC3 and LCC4 and EGRET compatible region have large sensitivity on tan b; EGRET Region LCC 4 Point BR(H+"tn) vs. tan b e+e- "H+H- "tbtn sensitive to tan b process produced with typical cross section of ~ 2 fb at 1 TeV giving BRs accuracy of O(3-6%).

32. Collider Experiments on Dark Matter Dark Matter Density Baltz, M.B., Peskin, Wiszanski,hep-ph/0602187

33. non-SUSY WIMP Dark Matter Several scenarios of New Physics may include a symmetry protecting a cold DM candidate: Warped Extra Dimensions, Radions, Universal Extra Dimensions,... UED interesting case study, with a phenomenology close to SUSY and particle at a mass scale below 1 TeV to comply with WMAP constraint. Tait, Servant

34. UED at High Energy LC UED phenomenology closely resembles SUSY; If UED related to DM density expect signals at LHC, at a multi-TeV LC, such as CLIC and possibly a 1 TeV ILC; CLIC 3 TeV KK Particle masses determined very accurately, if kinematically accessible:

35. UED at High Energy LC Nature of new particles can be clearly identified by a spin analysis, based on production properties and decay angles. UED SUSY M.B., Matchev et al. JHEP(2005) cos q

36. A Window on New Physics Indirect effect of exchange of new particles on Standard Model processes offers important opportunity to search for phenomena at scales >> centre-of-mass energies:

37. EW Observables s(e+e-gff) Cross sections Fermion Tag, Efficiency Asymmetries AFB ALR Fermion Tag, Charge Id, Polarization

38. Mass Reach at Tera-scale Frontier Extra Gauge Bosons Z’

39. Mass Reach at Tera-scale Frontier Anticipated experimental accuracy on EW observables needs to be matched by SM predictions accurate to O(1%) to ensure sensitivity to NP; Electroweak radiative corrections include large Sudakov logarithms which will contribute sizeable uncertainties Example: at 1 TeV W-boson corrections of the form amount to 19%.

40. ILC has potential to cover widest energy range of any accelerator; Physics program spans from high-precision EW tests of SM to search of new phenomena up to and above the scale accessed by LHC and detailed study of production and decay properties of new particles; 0.1 TeV 0.5 TeV 1.0 TeV This relies on efficient identification of fermion flavours, accurate reconstruction of multi-partons and availability of different beam particles, energy and polarization configurations.

41. Comparison of ILC Detector Performance Targets ILC Vertexing Tracking Calorimetry Jet Flavour Tagging H1 Momentum Resolution Jet Energy Resolution dpt/pt2 s Ejet (GeV) ATLAS ALEPH ILC ILC p (GeV) Ejet (GeV)

42. Tracking Performance Targets Simulated Heavy Higgs Pair at ILC B Vertices Extrapolation to Collision Point Momentum

43. Particle Flow Particle flow paradigm to accurate parton energy reconstruction in hadronic events; Determine jet energy as sum of momentum of charged particles measured in Main Tracker, energy of em photons in ECal and energy of neutral hadrons in HCal, high granularity crucial to minimize confusion term; W/Z boson separation Resolution requirements driven by W/Z/H boson separation in complex multi-jet final states such as: WWnn, ZZnn, HHZ, ZZZ, … LEP-like resolution ILC resolution

44. Calorimeter Granularity 4x4 cm2 Fraction ofgs 2x2 cm2 1x1 cm2 Distance from closest Track (cm)

45. ILC promises to complement and expand probe into TeV scale beyond LHC capabilities, matching energy reach and adding precision; Physics program will address many of the fundamental questions of today physics from origin of mass, to nature of Dark Matter; Linear Collider up to 1 TeV technically feasible, detectors matching precision requirements are being developed in world-wide R&D effort; Theoretical predictions at the level of anticipated accuracies are crucial, as well as clues on what the signals the LHC may soon be observing mean in optimisation of ILC program and capabilities.