1. ILC Project Hitoshi Yamamoto Tohoku University INSTR2014 Novosibirsk, February23, 2014

2. ILC (International Linear Collider) 31 km Damping ring Main linac electron Positron beam 500 GeV CM with 31 km → upgrade later to ~ 1TeV CM with 50 km IP beam size : 6 nm high, 500 nm wide 300  m long (@500 GeV CM) Luminosity 1.8 x 10 34 /cm 2 s (@500 GeV CM ） First stage : 250 GeV Higgs Factory e+ e- collider

3. ILC TDR Completion June 12, 2013 ‘A World-wide Event – from design to reality’ Tokyo Fermilab CERN

4. 4 LC Collaboration Director Lyn Evans LC Collaboration Director Lyn Evans ILC accelerator Mike Harrison ILC accelerator Mike Harrison ILC/CLIC Phys./Det. Hitoshi Yamamoto ILC/CLIC Phys./Det. Hitoshi Yamamoto CLIC accelerator Steinar Stapnes CLIC accelerator Steinar Stapnes LC Board Chair : Sachio Komamiya LC Board Chair : Sachio Komamiya Deputy Director Hitoshi Murayama Deputy Director Hitoshi Murayama LCC (LC Collaboration) New International LC Organization In full operation since June, 2013

5. ILC Timeline by LCC 2013 - 2016 – Negotiations among governments – Accelerator detailed design, R&Ds for cost-effective production, site study, CFS designs etc. – Prepare for the international lab. 2016 – 2018 – ‘Green-sign’ for the ILC construction to be given (in early 2016 ) – International agreement reached to go ahead with the ILC – Formation of the ILC lab. – Preparation for biddings etc. 2018 – Construction start (9 yrs) 2027 – Construction (500 GeV) complete, (and commissioning start) (250 GeV is slightly shorter)

6. ILC Physics

7. ILC features : cleanliness ■ Collision of two elementary particles proton + proton at LHC Proton = 3 quarks + gluons electron + positron at ILC → Signal is clearly seen without much noises LHC ILC All from Higgs → Theoretically clean (less theoretical uncertainties) → Trigger-less data taking proton quark gluon proton electron positron LHC ILC

8. ILC features : control ■ Initial state of electron-positron interaction : Energy-momentum 4-vector is specified Electron polarization (80%~90%) is specified Positron polarization (60%) is optional (30% comes for free) LHC ILC Energy-momentum 4-vector → e.g. recoil mass analysis: tagged Higgs Higgs to ALL (including invisible final state) H  H 

9. Electron polarization ee ee ,Z (B,A 0 ) Specify the intermediate state e.g. Right-handed e- turns off A 0 Information on the gauge structure of the final state Increase rates e.g. P - /P + =  0.8/+0.3 : Increases the H production mode  ( H) by X 2.34 (=1.8 x1.3 ) Background rejection Right-handed e- turns off W ee ee W+W+ WW e.g. acoplanar muon pair produciton such as smuon pair production

10. ILC @1 TeV At higher Ecm – W fusion dominant – More Higgs – New particles ! W fusion Higgsstrahlung Luminosity each energy for ~3 years Good for Higgs self coupling e+e- HH – Effect of irreducible diagrams less important  @ 1 TeV (  @500 GeV) →   ab -1 @ 1 TeV  Higgs production

11. Higgs Reconstruction At 250 GeV Recoil mass analysis dMH = 32 MeV (TDR) At 500 GeV 2 jet + nothing Main background = Z

12. ILC Luminosity Upgrade Options 250 GeV CM (Higgs factory) – X4 luminosity @ 3E34/cm 2 s – x2 Nbunch, x2 rep rate; 120 200 MW wall plug 500 GeV CM – x2 luminosity @3.6E34/cm 2 s – x2 Nbunch; 160 200 MW wall plug 1 TeV CM – x1.4 luminosity @5E34/cm 2 s – Aggressive beam params; Same wall plug power

13. Measurement errors of Higgs Couplings (Snowmass study – Higgs WG) All assume generation universality, no BSM → Fit – LHC ranges : optimistic (sys.err: theory = 1/2, exp. N -1/2 ), pessimistic (no change) Apart from  ILC is 1/3 ~ 1/10 of HL-LHC (w/o ILC lum upgarde) With ILC lum upgrade, additional ~1/2 in errors ILC can measure model-independently w/o assumptions above.

14. Top Yukawa Coupling Direct measurements Not a mode ILC is partifcularly good at

15.  tot to 5% – Br(H WW) & g(HWW) by e+e- H – Br(H ZZ) & g(HZZ) by e+e-  CP – 3~4% (on mixing coeff) by HZ cross sestion and production/decay angles – Or by H →  polarization)  to 6 ゜ w/ ab-1 at 350 GeV Higgs Width and CP

16. m t (msbar) to 100 MeV Sensitivity to ttH coupling at threshold Anomalous ttZ, tbW, ttg coup Top

17. New Particle Search LHC Difficulty when mass difference is small ILC Good sensitivity up to kinematic limit for (essentially) any mass difference

18. Fermion Compositeness ILC 500 GeV : e+ e- → ff + - : initial helicity

19. Z’ couplings to identify a model MZ’ = 2 TeV MZ’ = 4 TeV 1000 fb-1 at 500 GeV P- = 0.8, P+ = 0.6 e+ e- → l+l-

20. Dark Matter ■ Lightest super particle (LSP) is the dark matter? ■ Key: can the theory with measured parameters explain the ‘measured’ relic density? ■ Creation and annihilation → relic density Need to know processes contributing to LSP annihilation Relic density estimation by LHC (red) and ILC(blue) (SUSY B’ model) 20

21. ILC Accelerator

22. ILC: How it works Produce ： electron source Produce ： Positron source Accelerate ： main linac Align ： damping ring Focus ： final focus System Detect ： high-res detectors

23. 23 Low emittance : KEK ATF (Accelerator Test Facility) – Achieved the ILC goal. Small vertical beam size : KEK ATF2 – Goal = 37 nm, 65 nm achieved Limit is in measurement. No basic problem seen. Stabilize the beam at nm scale: KEK ATF2 – Feedback system successful (FONT) Align and Focus

24. Principle of acceleration – Generate strong RF wave in a cavity – Synchronize such that particle is always accelerated forward ILC accelerating cavity – Superconducting (niobium) – 1.3 GHz (L band ） – 9 cell, 1 m – Accelerting gradient Average 31.5 MV/m 250 GeV/31.5 MeV = 8000 cavities needed → ８ km (In reality 11 km/side ） Accelerate : Main LINAC 超電導加速空洞 (Ichiro cavity) 1 m

25. 25 Accelerating cavity – Spec: 31.5 MV/m ±(<20%) – >80% yield achieved (RDR goal achieved) Cryomodule assembly – Combine cavities from all over the world KEK S1-global successful Main LINAC Achievements ILC technology is now ‘ready’

26. Status of the ILC Mostly in Japan

27. International Supports Europe : ‘European Strategy’ (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. US : HEPAP facilities subpanel report (March 22, 2013) – The initiative from the Japanese particle physics community to host the ILC in Japan is very welcome, and the U.S. particle physics community looks forward to a proposal from Japan to discuss possible participation. – For the final US strategy, wait for the HEPAP subpanel (P5) report (March-May, 2014) 27

28. 32 Rebuilding true command tower functions that strongly advance science and technology policies –…We will actively promote the critical fields of energy creation, energy conservation, energy storage, etc. as knowledge-concentrated national strategies - for example, our country should be able to play a leading role in creation of international centers for scientific innovations such as the ILC (the international linear collider) project which is a grand project in the field of particle physics. 92 Creation of globally top-class centers for research and development –…We will significantly strengthen supports for universities and public research facilities that perform studies at levels above the intentional standards, such as significant expansion of WPIs and playing a leading role in creation of international centers for scientific innovations such as the ILC (the international linear collider construction) project which is a grand project in the field of particle physics. 28 Political support : LDP (Liberal Democratic Party : New Ruling Party) election platform ‘ILC’ appears twice explicitly

29. 29 Press conference by the MEXT minister Shimomura Jan 18, 2013 ‘(On ILC) We would like to consider the plan for the near future, while as the government actively negotiating with relevant countries in the first half of this year … we are now studying the legal framework.’ The Japanese government did start to talk to other governments.

30. Science Council of Japan Report submitted : Sep 30, 2013 30 …the Committee appreciates the need for and scientific significance of an electron-positron collider as a unique complement to the proton-proton collider. 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. (Official translation) MEXT has requested ~$0.5M for the investigatory study which was approved on Dec 24, 2013

31. A Letter to the DOE Secretary from the Federation of Diet Members for the ILC (~160 out of ~700 diet members total) Jan 8, 2014 31 … In Japan, for the first time ever, the government has allocated a budget for the coming Japanese fiscal year to investigate and examine the ILC itself… This has great significance in that the Japanese government has shown a vital interest in the ILC project. … The ultimate decision to host the ILC project rests with the Japanese government and the Diet. Both houses of the Diet are strongly in support of the ILC project. We have reached the stage where we must now work together with the other government for the realization of the ILC. The Japanese government intends to perform concentrated investigations and address the major issues and arrive at a conclusion about hosting the ILC by the end of JFY 2015.

32. 32 The most important issue for the realization of the ILC is whether it can become a truly global project. For this purpose, the Japanese government is currently gathering information from abroad and is starting talks with the United States and European countries about forming a partnership. … All 3 have served as the MEXT minister

33. ILC Candidate Sites in Japan Kyushu –Sefuri mountains Tohoku –Kitakami mountains ‘ILC site evaluation committee’ (JAHEP) Co-chairs: Kawagoe, Yamamoto evaluated them based on 1.Geology and other technical aspects 2.Socio-economic conditions Selected the Tohoku Site (Aug 23, 2013) Sefuri Kitakami

34. Kitakami Site Flexibility in positioning the 50 km route Shorter access tunnels Natural Drainage etc… 34 Ichinoseki-city Oshu-city Kesennuma-city Sendai

35. Summary With the discovery of Higgs, the physics case for the ILC is now stronger than ever ILC accelerator design is ‘ready’ with the completion of TDR The ILC detectors are pushing the state of the art of particle detection technologies Japanese government is now negotiating with other governments toward realization of a truly global ILC lab There are strong supports from the international scientific community. (will they translate to real commitments?) 35

36. Sefuri Site

37. ０．５ % tilt ILC route vertical cross section Kitakami Sefuri Matsuura River Below sea level ~100m above sea level