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Higgs Factory Workshop Fermilab , 14-16 2012 Experimental summary Alain Blondel

v. v. Higgs Factory Workshop Fermilab , 14-16 2012 Experimental summary Alain Blondel. Why a Higgs factory? Question 1: is the H(126) The Higgs boson -- do we know well enough from LHC ? -- how precisely do we need to know before we are convinced?

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Higgs Factory Workshop Fermilab , 14-16 2012 Experimental summary Alain Blondel

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  1. v v

  2. HiggsFactory Workshop Fermilab, 14-16 2012 Experimentalsummary Alain Blondel

  3. Why a Higgs factory? • Question 1: is the H(126) The Higgs boson • -- do we know well enough from LHC? • -- how precisely do we need to know before we are convinced? • Question 2: is there something else in sight? • -- known unknown facts need answer • neutrino masses, (Dirac, and/or Majorana, sterile and right handed, CPV, MH..) • non baryonic dark matter, • Accelerated expansion of the Universe • Matter-antimatter Asymmetry • -- can the Higgs be used as search tool for new physics that answer these questions? • -- precision measurements sensitive to the existence of new particles through loops • -- how precisely do we need to know before we are convinced? • Question 3: which Higgs factories ? • -- HL-LHC • -- (V)HE-LHC • -- mu+mu- • -- gamma-gamma • -- e+e- : linear and circular

  4. 1. Scalar boson H(126) has been discovered! 2. LHC has donebetterthanprojected hereis a plot from ATLAS in 2005, expected3-4with 10fb-1 at 14TeV

  5. It already looks like a Higgs Boson Spin-parity: looks like 0+! Couplings scale ~ mass… with scale = v Red line = SM, dashed line = best fit JE & Tevong You, arXiv:1303.3879

  6. Once the Higgs boson mass isknown, the Standard Model isalmostentirelydefined. -- with the notable exception of neutrino masses, nature & mixings but weexpectthese to bealmostcompletelydecoupledfromHiggs observables. (true?) Does H(125.9) Fully accounts for EWSB (W, Z couplings)? Couples to fermions? Accounts for fermion masses? Fermion couplings ∝ masses? Are there others? Quantum numbers? SM branching fractions to gauge bosons? Decays to new particles? All production modes as expected? Implications of MH ≈ 126 GeV? Any sign of new strong dynamics? yourBanker’s question: Whatprecisionisneeded to discover /rule out somethinginteresting?

  7. Some guidance fromtheorists: • New physics affects the Higgs couplings • SUSY , for tanb = 5 • Composite Higgs • Top partners • Other models may give up to 5% deviations with respect to the Standard Model • Sensitivity to “TeV” new physics needs per-cent to sub-per-cent accuracy on couplings for 5 sigma discovery. • LHC discovery/(or not) at 13 TeV will be crucial to understand the strategy for future collider projects R.S. Gupta, H. Rzehak, J.D. Wells, “How well do we need to measure Higgs boson couplings?”, arXiv:1206.3560 (2012) H. Baer et al., “Physics at the International Linear Collider”, in preparation, http://lcsim.org/papers/DBDPhysics.pdf

  8. The LHC is a Higgs Factory ! 1M Higgs already produced – more than most other Higgs factory projects. 15 Higgs bosons / minute – and more to come (gain factor 3 going to 13 TeV) Difficulties: several production mechanisms to disentangle and significantsystematics in the production cross-sections prod. Challenge willbe to reducesystematics by measuringrelatedprocesses. if observed prod (gHi )2(gHf)2 extractcouplings to anythingyoucansee or producefrom H if i=f as in WZ with H ZZ  absolutenormalization

  9. Couplings at HL-LHC: ATLAS MC Samples at 14 TeVfrom Fast-Sim. Truth with smearing: best estimate of physics objects dependency onpile-up Validated with full-sim. up to m~70 Analyses included in ATLAS study: Hgg0-jet and VBF H  ttVBF lep-lep and lep-had H  ZZ  4l H WW  lnln0-jet and VBF WH/ZH  gg ttH gg (ttH mm) Direct top Y coupling H  mm Second generation fermion coupling HH bb ggHiggsSelf-Couplings ttH gg Very Robust channel Good S/B Statistically limited F.Cerutti - Higgs Factory

  10. c) The discovery of the Higgs boson is the start of a major programme of work to measure this particle’s properties with the highest possible precision for testing the validity of the Standard Model and to search for further new physics at the energy frontier. The LHC is in a unique position to pursue this programme. HL-LHC (3 ab-1 at 14 TeV): Highest-priority recommendation from European Strategy No measurementgHcc and GH Assume no exoticScalardecays ? ? ? In bold, theory uncertainty are assumed to be divided by a factor 2, experimental uncertainties are assumed to scale with 1/√L, and analysis performance are assumed to be identical as today • Couplingmeasurementswithprecision : • in the range 6-15% with LHC - 300 fb-1 • in the range 1-10%with HL-LHC - 3000 fb-1 NB: at LEP theoryerrors improved by factor 10 or more….

  11. t H Full HL-LHC Z W b  

  12. HiggsFactoriesDreams

  13.  collider

  14. m+m-Collider vse+e-Collider ? [16,17] , W, … • A m+m-collider can do things that an e+e-collider cannot do • Direct coupling to H expected to be larger by a factor mm/me • ,jh[speak = 70 pb at tree level] • Can it be built + beam energy spread dE/E be reduced to 3×10-5 ? • 4D+6D Cooling needed! • For dE/E = 0.003% (dE~ 3.6 MeV, GH ~ 4 MeV) • no beamstrahlung, reduced bremsstrahlung • Corresponding luminosity ~ 1031-32 cm-2s-1 • Expect 2300-23000 Higgs events in 100 pb-1/ year • Using g-2 precession, beam energy and energy spectrum • Can be measured with exquisite precision (<10 keV) • From the electrons of muon decays • Then measure the detailed lineshape of the Higgs at √s ~ mH • Five-point scan, 50 + 100 + 200 + 100 + 50 pb-1 • Precision from H→bb and WW : , W, … s (pb) √s s(mH), TLEP HF2012 : Higgs beyond LHC (Experiments)

  15. Wyatt, Cracow ILC:

  16. ILC in a Nutshell Polarised electron source Damping Rings Ring to Main Linac (RTML) (inc. bunch compressors) e+ Main Linac Beam Delivery System (BDS) & physics detectors Beam dump Polarised positronsource e- Main Linac not too scale

  17. Drive beam time structure - initial Drive beam time structure - final 240 ns 240 ns 5.8 ms 140 ms train length - 24  24 sub-pulses 4.2 A - 2.4 GeV – 60 cm between bunches 24 pulses – 101 A – 2.5 cm between bunches CLIC Layout at 3 TeV Goal: Lepton energy frontier Drive Beam Generation Complex Main Beam Generation Complex D. Schulte, CLIC, HF 2012, November 2012

  18. Circular e+e- colliders to study THE BOSON X(126) a veryyoung concept (althoughthereweremanypredecessors)

  19. 80 km ring in KEK area 12.7 km KEK

  20. 105 km tunnel near FNAL (+ FNAL plan B from R. Talman) H. Piekarz, “… and … path to the future of high energy particle physics,” JINST 4, P08007 (2009)

  21. What is a (CHF + SppC) China Higgs Factory (CHF) Circular Higgs factory (phase I) + super pp collider (phase II) in the same tunnel pp collider ee+ Higgs Factory HF2012

  22. prefeasibilityassessment for an 80km projectat CERN John Osborne and Caroline Waiijer ESPP contr. 165

  23. LEP3, TLEP(e+e- -> ZH, e+e- →W+W-, e+e- →Z,[e+e-→t ) key parameters 2-8 times ILC lumi at ZH thresh. 10-40 times ILC lumi at ZH thresh. at the Z pole repeating LEP physics programme in a few minutes…

  24. Performance of e+ e- colliders TLEP : Instantaneous lumi at each IP (for 4 IP’s) Instantaneous lumi summed over 4 IP’s Z, 2.1036 WW, 6.1035 HZ, 2.1035 tt , 5.1034 R. Aleksan • Luminosity : Circular colliders can have several IP’s Notes : • Lumiupgrade (×3) now envisioned at ILC : luminosity is the key at low energy! • Crossing point between circular and linear colliders ~ 400 GeV • With fewer IP’s expect luminosity of facility to scale approx as (NIP)0.5 – 1

  25. Higgs Production Mechanism in e+ e- collisions For a light Higgs it is produced by the “higgstrahlung” process close to threshold Production xsection has a maximum at near threshold ~200 fb 1034/cm2/s  20’000 HZ events per year. Z – tagging by missing mass e- H Z* Z e+ For a Higgs of 125GeV, a centre of mass energy of 240GeV is sufficient  kinematical constraint near threshold for high precision in mass, width, selection purity

  26. ILC Z – tagging by missing mass total rate  gHZZ2 ZZZ final state  gHZZ4/ H  measure total widthH emptyrecoil = invisible width ‘funnyrecoil’ = exoticHiggsdecay easy control belowtheshold e- H Z* Z e+

  27. Higgs Physics with high-energy e+e- colliders 1. Similar precisions to the 250/350 GeV Higgs factory for W,Z,b,g,tau,charm, gamma and total and invisible width 2. ttHcoupling possible withsimilarprecision as HL-LHC (4%) 3. Higgs self couplingalsoverydifficult… precision 30% at 1 TeVsimilar to HL-LHC prelim. estimate 10-20% at 3 TeV (CLIC)  Forthe study of H(126) alone, the high energy e+e- collideris not compelling w.r.t. one workingat 240 GeV.  other motivation is new particlefound (or inferrred) at LHC for whiche+e- collisions bringsubstantial new information

  28. Higgs factory performances Precision on couplings, cross sections, mass, width, … Summary of the ICFA HF2012 workshop (FNAL, Nov. 2012) arxiv1302:3318 Best precision

  29. Progress on the theoretical side also needed J. Ellis et al. • Same assumptions as for HL-LHC for a sound comparison • Assume no exotic decay for the SM scalar • ILC complements HL-LHC for (gHcc, GH, Ginv) • TLEP reaches the sub-per-cent precision (>1 TeV BSM Physics)

  30. Performance Comparison • Expected precision on the total width • Same conclusion when GH is a free parameter in the fit TLEP : sub-percent precision, adequate for BSM Physics sensitivity beyond 1 TeV

  31. Asymmetries, Lineshape Precision tests of EWSB WW threshold scan WW production - tt threshold scan • TLEP : Repeat the LEP1 physics programme every 15 mn • Transverse polarization up to the WW threshold • Exquisite beam energy determination (10 keV) • Longitudinal polarization at the Z pole • Measure sin2θW to 2.10-6 from ALR • Statistics, statistics …

  32. The Next-to-Next Facility L. Rossi 20 T field! • TLEP can be upgraded to VHE-LHC • Re-use the 80 km tunnel to reach 80-100 TeVpp collisions • Or re-use the LHC tunnel to reach 27-33 TeVpp collisions • In both cases, need to develop 16-20 T SC magnets • Needs lots of R&D and time (TLEP won’t delay VHE-LHC) • First consistent conceptual design • Using multiple SC materials

  33. The Next-to-Next Facility H H H M. Mangano HE-LHC VHE-LHC H H • Performance comparison for the SM scalar • Measurement of the more difficult couplings : gHtt (Yukawa) and gHHH(self) • In e+e- collisions • In pp collisions

  34. The Next-to-Next Facility (5) • Performance comparison for the SM scalar (cont’d) • Only ttH and HHH couplings • Other couplings benefit only marginally from high √s • VHE-LHC : Largest New Physics reach and best potential for gHtt and gHHH (NP=New Physics reach) √s, NP J. Wells et al. arXiV:1305.6397 TLEP √s, NP HF2012 ILC500, HL-LHCILC1TeV, HE-LHCCLIC3TeV, VHE-LHC

  35. At the moment we do not know for sure whatis the most sensible scenario LHC offered 3 possible scenarios: (could not lose) Discoverthatthereisnothing in thisenergy range.  This would have been a great surprise and a greatdiscovery! Discover SM Higgs Boson andthatnothingelse iswithinreach • Most Standard scenario • greatdiscovery! Discovermany new effects or particles • greatdiscovery! Keeplooking in 13/14 TeV data! NO But…. So far we are here Answer in 2018 High precision High energy BE PREPARED!

  36. Conclusions • Discovery of H(126) and European Strategy brought momentum • News ideas emerging for scalar factories and beyond • Prospects for the future look very promising • The HL-LHC is already an impressive Higgs Factory. • It is important to choose the right machine for the future • Cannot afford to be wrong for 10 billion CHF ! -- Must bring order of magnitude improvement wrt LHC • Results of the LHC run at 14 TeV will be a necessary and precious input • Towards an ambitious medium and long term vision • In Europe: Decision to be taken by 2018 -- design study recommended and being organized • A large e+e- storage ring collider is a very promising option • Precision and high luminosity • Most mature technology • A first step towards a 100 TeV proton proton collider and a long term vision.

  37. Design Studyisnowstarting ! Visithttp://tlep.web.cern.ch and suscribe for work, informations, newsletter Global collaboration: next meeting atFermilab, collaboratorsfrom Europe, US, Japan, China

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