1. Hitoshi Yamamoto, Tohoku University KIAS-CFHEP Workshop November 13, 2015 1

2. Plan of talk ILC parameters and the sample running scenario ILC parameters and the sample running scenario Physics updates according to the sample running scenario Physics updates according to the sample running scenario Accelerator Accelerator Detectors Detectors Political status Political status 2

3. ILC : Parameters and the Sample Running Scenario 3

4. 31 km Damping ring Main linac electron Positron beam Ecm = 500 GeV, L = 1.8 x 10 34 /cm 2 s Polarization (e+/e-) = ±0.3/±0.8 2x10 10 particles/bunch, 1312 bunch/train, 5 trains/sec Beam size at IP :  y = 5.9nm,  x = 474nm,  z = 300  m Average accelerating gradient = 31.5 MV/m Wall plug power = 163 MW 4 1st Phase Baseline: 500 GeV ILC1st Phase Baseline: 500 GeV ILC

5. ILC at Lower Energies (The baseline 500 GeV machine running at lower energies) 250 GeV CM Average accelerating gradient = 14.7 MV/m Wall plug power = 122 MW L = 0.75 x 10 34 /cm 2 s Run the linac at 10 Hz, alternate e+ production and luminosity (150 GeV e- beam is required to produce enough e+’s) 350 GeV CM Average accelerating gradient = 21.4 MV/m Wall plug power = 121 MW L = 1.0 x 10 34 /cm 2 s Bunch population/pattern, polarizations are the same as for the baseline 500 GeV 5

6. ILC Luminosity UpgradesILC Luminosity Upgrades 250 GeV CM X4 luminosity @ 3E34/cm 2 s x2 Nbunch, x2 rep rate (10Hz); 122 200 MW wall plug Use a longer undulator to produce enough e+’s by 125 GeV e- beam: no need to alternate e+ production and luminosity 500 GeV CM x2 luminosity @3.6E34/cm 2 s x2 Nbunch; 163 204 MW wall plug 6

7. ILC Running ScenarioILC Running Scenario Ability to run at various energies: a merit of the ILC Can the stated luminosities at different energies be taken in a reasonable total running time? Realistic ramp up profiles and down time for upgrade should also be taken into account → ‘Standard sample running scenario’ for up to 500 GeV to run for ~20 years total (ref: ~25 years for LHC) Actual running scenario will depend on physics outcomes from LHC and ILC, and other factors 7

8. Standard Sample ILC Running ScenarioStandard Sample ILC Running Scenario After examining various scenarios, one scenario (H20) was recommended by the ILC parameters WG and approved by the LCB (Linear Collider Board) 8 Reference: Snowmass study ‘H20’ Total 250GeV 1500fb-1 350GeV 200fb-1 500GeV 4000fb-1

9. ILC Physics Update according to the sample running scenario 9 Higgs Top New Particles Others+ Highlights only!

10. Two documents:Two documents: ‘ILC Operating Scenarios’ By the ILC parameters Working Group of LCC arXiv:1506.07830 ‘Physics Case for the International Linear Collider’ By the Physics Working Group of LCC arXiv:1506.05992 Both are found at http://www.linearcollider.org/P-D/Documentshttp://www.linearcollider.org/P-D/Documents ‘Standard references’

11. Higgs Couplings model independent 11 No assumption for generation universality, unitarity, nor on BSM. Absolute measurements of decay rates Apart from  t  accuracy is ~1 % or less Level that is meaningful in distinguishing models H20

12. Higgs Couplings model discrimination 12 The pattern of deviation from SM tells BSM models apart In general, Higgs couplings needs to be measured to ~1% or better

13. Higgs Couplings: compare with LHC model dependent 13 All assume generation universality, no BSM → Fit : model-dependent CMS-1: HL-LHC pessimistic (sys err : no change) CMS-2: HL-LHC optimistic (sys.err : theory = 1/2, exp. N -1/2 ) Apart from  ILC (H20) is 1/5 ~ 1/15 of HL-LHC Statistical power of ILC: ~100 HL-LHC running simultaneously ILC is for 1IP, HL-LHC is for CMS only If CMS and ATLAS are combined, error would decrease (1/sqrt2 if stat-dominated, ~no decrease if sys-dominated) H20

14. Notes on Higgs CouplingsNotes on Higgs Couplings 14 For  Z and  W, production rates give high precision e+e- → ZH for  Z and e+e- → H for  W [with Br(H→bb)] In general for  X,  tot is necessary in addition to Br(H→x)  tot = Br(H→ZZ)/  (H→ZZ) with  (H→ZZ) from  Z  tot = Br(H→WW)/  (H→WW) with  (H→WW) from  W W mode is far more powerful: 350 GeV or higher running is necessary to fully make use of ILC capability For   , LHC and ILC are combined Br(H→  )/Br(H→ZZ) by LHC and  Z by ILC Physics: Higgs self coupling 1TeV: 16% with 2000 fb-1, 10% with 5000 fb-1 500 GeV: 27 % with 4000 fb-1 (H20)

15.  t (by e+e-→ttH): 500 GeV vs 550 GeV 15 e+e- → ttH cross section increases by nearly x4 by 500 GeV →550 GeV →  t error reduces by ½ (6% to 3%) by running at 550 GeV instead of 500 GeV ttH cross section top coupling error Normalized

16. Extend the total length to ~50 km Add 45 MV/m cavities (keep the old ones) Average accelerating gradient = 38.2 MV/m Wall plug power = 300 MW Beam size at IP :  y = 2.8 nm,  x = 481 nm,  z = 250  m Smaller by the boost 2450 bunches/train, 4 trains/s L = 3.6 x 10 34 /cm 2 s Upgrade: x1.4 luminosity @4.9E34/cm 2 s Aggressive beam parameters: smaller  x and  z Same wall plug power (300 MW) 16

17. Threshold scan determines Re(pole) to 50 MeV (mostly theoretical) The msbar top mass can be obtained from Re(pole) with 10 MeV theoretical uncertainty Theoretical uncertainties will improve over time Bonus: Sensitivity to ttH coupling at threshold (vertex correction) Top at Threshold (@~350 GeV)

18. 18 Top Mass @ ThresholdTop Mass @ Threshold Theoretical systematic error is to go down significantly for ILC, but not so for LHC HL-LHC 3000 fb -1 √s=14 TeV ILC 200 fb -1 √s=350 GeV Stat+Sys Stat ‘H20’(sample running scenario) Stat+Sys Top quark mass (msbar) (@350 GeV: CLIC+ILC study) HL-LHC 3000 fb -1 √s=14 TeV ILC 100 fb -1 √s=350 GeV Stat+Sys Stat Stat+Sys Stat Snowmass ILC500-up

19. Top Pair Production at 500 GeVTop Pair Production at 500 GeV 19 Use beam polarization (separates  and Z, R and L) Anomalous top-Z couplings Distinguish variety of BSM models e+e- → ttbar

20. New Particle SearchNew Particle Search LHC: Difficulty when mass difference is small ILC: Good sensitivity up to kinematic limit for (essentially) any mass difference In general: LHC can reach higher energy but could miss important phenomena ‘Other than special contrived cases, LHC would find it if it is there’ – true? Apart from the fact that near degeneracy cases are quite ‘natural’…. 20

21. 21 Tevatron has a long list of glorious physics achievements (top discovery etc.) For Higgs, however, it did not see clear signal even though ~20000 Higgs Were produced. Needed to wait for LHC (~1M Higgs produced in Run 1) At ILC, only a handful of Higgs (a few tens) will do Hadron and Lepton MachinesHadron and Lepton Machines FNAL Tevatron

22. Z’ at ILC: TDR Study 22 Can determine the couplings (V and A) of Z’ to leptons Beam polarization is essential ILC running plan: 4ab-1 at 500 GeV → error contour is half the size of the dotted line e+e-→l+l- Sample running scenario has 4ab-1 at 500 GeV

23. An interesting Event 13 GeV LHC 23 Mee = 2.9 TeV Background ~ 0.002 If this is a Z’, then Run1 should have seen several 10’s ?

24. Accelerator 24

25. 25 Low emittance : KEK ATF (Accelerator Test Facility) Achieved the ILC goal. Small vertical beam size : KEK ATF2 Goal = 37 nm, 44 nm achieved No basic problem seen. Stabilize the beam at nm scale: KEK ATF2 Feedback system successful (FONT) Small Emittance and FocusingSmall Emittance and Focusing

26. 26 Accelerating cavity Spec: 31.5 MV/m ±(<20%) >80% yield (RDR goal achieved) Cryomodule assembly Combine cavities from all over the world KEK S1-global successful Main AccelerationMain Acceleration

27. 27 Kitakami Candidate SiteKitakami Candidate Site ~50 km Now the only candidate site for which studies are being made 50 km line can be taken with flexibility Access tunnels can be reasonably short (mild terrain) Natural drainage to nearby rivers is possible Vertical shaft to detector hall can be used

28. 28 Vertical Access to Detector HallVertical Access to Detector Hall TDR baseline for Asian site: horizontal access Difficult to transport heavy and large pieces Vertical access (~ 90 m depth) Large piece can be assembled on surface and then lowered by a gantry crane Merit of vertical access Detector can be assembled while detector hall is dug and equipped Cost and time Construction time is reduced by ~1 year Cost is likely to be reduced Vertical access: Adopted as new baseline （ LCC Change Management Process)

29. 29 Geological SurveysGeological Surveys 6 drillings, 10 km each of seismic and electric surveys Field survey 10 personmonth 31 km Seismic survey Electric survey

30. Geological Survey SummaryGeological Survey Summary 30 Some erosions near surface It seems that there is a solid granite bedrock at the beam line There are locations with deep heat erosions Overall no serious problems are found H24-No1: core sample

31. Detectors Require unprecedented performances to fully harvest ILC’s potential 31

32. Impact parameter resolution ILC Belle ATLAS LHCb Alice

33. Jet Energy Measurement: Charged particles Use trackers Neutral particles Use calorimeters Remove double-counting of charged showers Requires high granularity PFA (particle flow algorithm) PFA (particle flow algorithm) #chECALHCAL ILC (ILD)100M10M LHC76K(CMS)10K(ATLAS) X10 3 for ILC Need new technologies ! (Si pads, GEM, RPC, etc.) ILD Jet energy resolution ~ ½ of LHC

34. SiD High B field (5 Tesla) Small ECAL ID Small calorimeter volume Finer ECAL granularity Silicon main tracker ILD Medium B field (3.5 Tesla) Large ECAL ID Particle separation for PFA TPC for main tracker Two Detectors Based on PFA idea

35. ILC: Political Status 35

36. 36 Science Council of Japan on ILCScience Council of Japan on ILC The Committee suggests that the government of Japan should (1) secure the budget required for the investigation of various issues to determine the possibility of hosting the ILC, and (2) conduct intensive studies and discussions among stakeholders, including authorities from outside high- energy physics as well as the government bodies involved for the next two to three years. In parallel, it is necessary to have discussions with the research institutes and the responsible funding authorities of key countries and regions involved outside of Japan, and to obtain clear understanding of the expected sharing of the financial burden. Requested by MEXT; Report submitted on Sep 30 2013 The conclusion of the report included: (MEXT: Ministry of education, culture, sports, science and technology)

37. MEXT ILC Advisory PanelMEXT ILC Advisory Panel MEXT has requested and obtained $0.5M/year for investigatory study in 2014 and 2015. $1M requested for 2016 ‘ILC Advisory Panel’ was established under MEXT (Early 2014) Report to be completed by FY2015 (i.e. end of March 2016) (even though extendable) Two+1 working groups under the ILC Advisory Panel 1.Particle&Nuclear Physics workging group On the ILC physics case with respect to other future projects 2.TDR validation working group On the financial and human resources as well as maturity of design 3.Newly setup: Human resources working group 37

38. MEXT on the ILC MEXT on the ILC 38 ILC Taskforce ILC Advisory Panel Particle&nuclear physcis working group TDR validation working group MEXT Science Council of Japan Recommendation Sep 30, 2013 MEXT: Ministry of education, culture, sports, science and technology

39. Academic Experts Committee Interim SummaryAcademic Experts Committee Interim Summary 39 ‘The ILC is considered to be important because of its capability to investigate new physics beyond the Standard Model by exploring new particles and precisely measuring the Higgs boson and top quark. It should be also noted that the ILC might be able to discover a new particles which are difficult to be detected in LHC experiments.’ ‘ILC experiments are able to search for new particles, different from the ones that LHC experiments have been searching for. In case these new particles are supersymmetric particles, ILC and LHC experiments can study them complementally. On the other hand ILC experiments can carry out more precise measurement of the Higgs boson and the top quark, which are beyond the reach of LHC experiments.’ On the scientific merit of the ILC June 25, 2015

40. Three Recommendations 40 Recommendation 1: The ILC project requires huge investment that is so huge that a single country cannot cover, thus it is indispensable to share the cost internationally. From the viewpoint that the huge investments in new science projects must be weighed based upon the scientific merit of the project, a clear vision on the discovery potential of new particles as well as that of precision measurements of the Higgs boson and the top quark has to be shown so as to bring about novel development that goes beyond the Standard Model of the particle physics. Recommendation 2: Since the specifications of the performance and the scientific achievements of the ILC are considered to be designed based on the results of LHC experiments, which are planned to be executed through the end of 2017, it is necessary to closely monitor, analyze and examine the development of LHC experiments. Furthermore, it is necessary to clarify how to solve technical issues and how to mitigate cost risk associated with the project. Recommendation 3: While presenting the total project plan, including not only the plan for the accelerator and related facilities but also the plan for other infrastructure as well as efforts pointed out in Recommendations 1 & 2, it is important to have general understanding on the project by the public and science communities. (These recommendations are issues for MEXT still to investigate)

41. Letter from ICFA to ILC Advisory Panel Letter from ICFA to ILC Advisory Panel 41 27 August 2015 The chair of the International Linear Collider Advisory Panel Professor Shinichi Hirano Dear Professor Hirano: At its recent meeting, the International Committee for Future Accelerator ICFA(1) composed of directors of leading international particle physics laboratories and representatives of the word-wide particle physics community, discussed the document “Summary of the International Linear Collider (ILC) Advisory Panel’s Discussion to Date” produced by your panel. ICFA thanks you for the significant effort by you and the panel to study the ILC and its possible realization in Japan. We appreciate your very important summary document which indicates the serious interest of Japan in hosting a linear collider and which we take as an encouragement for the work of the worldwide ILC community. ICFA is preparing a short document to clarify some of the issues and questions raised in your summary. The document will be submitted to your panel before the end of this year. We would be pleased to assist in obtaining further information in case the need arises in the course of your investigation. Sincerely Joachim Mnich DESY Research Director Chair of ICFA ILC Advisory Panel Shinichi Hirano ICFA Chair Joachim Mnich

42. JS-Japan Parliamentary Coorperation 4 areas: Existing large-scale projects: Space (ISS, GPS etc.) Nuclear energy (fuel cycle, plasma technology) New areas Advanced accelerators (ILC and applications) Next-generation supercomputing Preparations are on-going April 2015: Two ex MEXT ministers et al. met with key members of the US government and both houses Collaborative work for ILC between AAA （ Advanced Accelerator Association promoting science and technology of Japan) and Hudson Institute has begun Diet members from Japan will visit Washington DC next Jan. to initiate a formal framework of cooperation (US-Japan Parliamentary Friendship League and Federation of Diet Members for the ILC) 42 US-Japan alliance and cooperation on advanced science and critical technologies

43. JS-Japan agreement on HEP Caroline Kennedy’s twitter: ‘US & Japan sign project agreement to advance cooperative research in high energy physics. ’ This overwrites the current US-Japan agreement on HEP 43 DOE: Jim Siegrist KEKDG Masa Yamauchi One item: Key Accelerator Technologies, including Linear Collider Technologies High Intensity/Luminosity Accelerator Technologies Superconducting Accelerator Technologies, and Advanced Accelerator Technologies

44. Summary ILC’s cleanliness and control lead to significantly extended discovery potential for new physics wrt HL-LHC. When any new particle is within kinematic reach, ILC can find it in most cases, and figure out the structure of the new physics. (ILC is good at unpredicted phenomena!) The ILC technology is now ready and site-specific designs are accelerating Political supports are strong both domestically and internationally. Japanese government is seriously evaluating cases for the ILC, and in parallel, initiating high-level contacts with other countries 44

45. Backup 45

46. MEXT Minister US VisitMEXT Minister US Visit January 10, 2014 MEXT minister Shimomura visited US and met with DOE secretary E. Moniz Facebook of MEXT Minister ‘Visited Moniz DOE director, and discussed about the ILC etc.’(mentioned explicitly only about the ILC) 46

47. 47 European Strategy Issued on March 22, 2013 There is a strong scientific case for an electron-positron collider, complementary to the LHC, that can study the properties of the Higgs boson and other particles with unprecedented precision and whose energy can be upgraded … The initiative from the Japanese particle physics community to host the ILC in Japan is most welcome, and European groups are eager to participate. Europe looks forward to a proposal from Japan to discuss a possible participation.

48. 48 On the scientific case of the ILC ‘we emphasize most strongly that the scientific justification for the project is compelling’ On the US participation in the ILC ‘As the physics case is extremely strong, all Scenarios include ILC support at some level through a decision point within the next 5 years’ ‘Unconstrained budget’ (Scenario C) ： ‘Play a world-leading role in the ILC experimental program and provide critical expertise and components to the accelerator, should this exciting scientific opportunity be realized in Japan’ US : P5 Report ( May 23, 2014) P5 chair, Steven Ritz SCIPP director, UCSC (Particle Physics Projects Prioritization Panel)

49. LINEAR COLLIDER COLLABORATION Designing the world’s next great particle accelerator Underground Facilities around the Detector Hall From the EDMS Meeting @KEK 2.12.2014 Assembly Hall Main Shaft Utility Shaft Damping Ring BDS Access Portal Detector Hall Access Tunnel 3D Design Integration model: Underground and Surface Facilities Bird’s-eye view image of the Underground Facilities at IR 49 Utility Cavern Utility Building