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Precision EW measurements at Future accelerators

Precision EW measurements at Future accelerators. ‘Will redo te LEP program in a few minutes…. ’. 1994-1999: top mass predicted (LEP, mostly Z mass&width ) 03/94 top quark discovered ( Tevatron ) 06/95

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Precision EW measurements at Future accelerators

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  1. Precision EW measurements at Future accelerators ‘Will redo te LEP program in a few minutes…. ’ Alain Blondel Precision EW measurements at future accelerators

  2. 1994-1999: top mass predicted (LEP, mostly Z mass&width)03/94 top quark discovered (Tevatron) 06/95 t’Hooft and Veltmanget Nobel Prize10/98 (c) Sfyrla

  3. 1997-2013 Higgs boson mass cornered(LEP H, MZetc +Tevatron mt , MW) Higgs Boson discovered (LHC) Englert and Higgsget Nobel Prize (c) Sfyrla

  4. Is it the end?

  5. Is it the end? Certainly not! -- Darkmatter -- Baryon Asymmetry in Universe -- Neutrino masses are experimentalproofsthatthereis more to understand. We must continue ourquest HOW?

  6. 1. ELECTROWEAK PRECISION TESTS (EWPT) Due to the non-abelian Gauge theory, Electroweak observables offersensitivity to electroweaklycoupled new particles ... -- if they are nearby in Energyscale or -- if theyviolatesymmetries of the Standard Model (in which case, no «decoupling») Higgs boson and top-bottom mass splittingconstituresuchsymmetry violations 2. TESTS OF ELECTROWEAK SYMMETRY BREAKING (EWSB) Is the H(125) a Higgs boson?  couplingsproportional to mass? if not couldbe more complicated EWSB e.g. more Higgses  Higgssupposed to cancel WW scattering anomalies at TeVscale doesthiswork? Alain Blondel Precision EW measurements at future accelerators

  7. EWRCs relations to the well measured GF mZ aQED at first order: Dr = a /p (mtop/mZ)2 - a /4p log (mh/mZ)2 e3 = cos2qwa /9p log (mh/mZ)2 dnb=20/13 a /p (mtop/mZ)2 completeformulaeat 2d order includingstrong corrections are available in fitting codes e.g. ZFITTER , GFITTER

  8. The main players Inputs: GF = 1.1663787(6) × 10−5/GeV2 from muon life time 6 10-7 MZ = 91.1876 ± 0.0021 GeV Z line shape 2 10-5 α = 1/137.035999074(44)electron g-23 10-10 EW observables sensitive to new physics: MW = 80.385 ± 0.015 LEP, Tevatron2 10-4 sin2Weff = 0.23153 ± 0.00016 WA Z pole asymmetries7 10-4 Nuisance paramenters:  (MZ) =1/127.944(14) hadronic corrections 1.1 10-4 to running alpha S (MZ) =0.1187(7) strong coupling constant 7 10-3 mtop = 173.34 ± 0.76 GeVfromLHC+Tevatron4 10-3 combination mH = ATLAS 125.36 ± 0.37 (stat) ± 0.18 (syst) GeV 125.17 ± 0.25 2 10-3 CMS 125.03 ± 0.26 (stat) ± 0.14 (syst) GeV Alain Blondel Precision EW measurements at future accelerators

  9. FUTURE ACCELERATORS 1. High Luminosity LHC (3000 fb-1 @ 14 TeV)  2035 An essentiallyapproved program 2. ILC as GigaZ, MegaW, Higgs and top factory A very ‘mature’ study of a new technique 3. Circulare+e- Z,W,H,topfactories A «young» study of a very mature technique 4. 100 TeV hadron collider $$$$$$$$$$$ Alain Blondel Precision EW measurements at future accelerators

  10. SNOWMASS report References: LEP Z peakpaperarXiv:hep-ex/0509008Phys.Rept.427:257-454,2006 LEP2 Electroweakpaper arXiv:1302.3415 [hep-ex] Phys. Rep. Gfitter Group arXiv:1209.2716v2 The Electroweak Fit of the Standard Model after the Discovery of a New Boson at the LHC J. Erler and P. Langacker ELECTROWEAK MODEL AND CONSTRAINTS ON NEW PHYSICS PDG dec 2011 «and referencestherein» Alain Blondel Precision EW measurements at future accelerators

  11. Alain Blondel Precision EW measurements at future accelerators

  12. Alain Blondel Precision EW measurements at future accelerators

  13. NB (AB): time scale (2030++) istypical of any new machine @ CERN or with CERN contribution; no real fundinguntil HL-LHC upgrade iscomplete. Alain Blondel Precision EW measurements at future accelerators

  14. http://cern.ch/fcc and http://cern.ch/fcc-ee first NB (AB): time scale for FCC-eesimilar to CLIC (2030++) Alain Blondel Precision EW measurements at future accelerators

  15. Alain Blondel Precision EW measurements at future accelerators

  16. Goal performance of e+ e- colliders FCC-ee as Z factory: 1012 Z (possibly1013withcrab-waist) possible upgrade complementarity ww NB: ideas for lumiupgrades: -- ILC arxiv:1308.3726 (not in TDR). Upgrade at 250GeV by reconfiguration after 500 GeV running; under discussion) -- FCC-ee(crabwaist)

  17. At the end of LEP: Phys.Rept.427:257-454,2006 N = 2.984 0.008 - 2  :^) !! This isdeterminedfrom the Z line shape scan and dominated by the measurement of the hadronic cross-section at the Z peak maximum  The dominant systematicerroris the theoretical uncertainty on the Bhabha cross-section (0.06%) whichrepresents an error of 0.0046 on N Improving on N by more than a factor 2 would require a large effort to improve on the Bhabha cross-section calculation!

  18. Neutrino counting at TLEP given the very high luminosity, the following measurement can be performed

  19. Beampolarization and E-calibration @ TLEP Precisemeast of Ebeam by resonantdepolarization ~100 keVeach time the meastismade At LEP transverse polarizationwasachievedroutinelyat Z peak. instrumental in 10-3measurement of the Z width in 1993 led to prediction of top quark mass (179+- 20 GeV) in March 1994 Polarization in collisions wasobserved(40% at BBTS = 0.04) At LEP beamenergyspreaddestroyedpolarizationabove 60 GeV E  E2/ At TLEP transverse polarization up to at least 80 GeV to go to higherenergiesrequiresspin rotators and siberiansnake TLEP: use ‘single’ bunches to measure the beamenergycontinuously no interpolation errors due to tides, ground motion or trains etc… << 100 keVbeamenergy calibration around Z peak and W pair threshold. mZ~0.1 MeV, Z ~0.1 MeV, mW ~ 0.5 MeV

  20. 350 GeV: the top mass • Advantage of a very low level of beamstrahlung • Could potentially reach 10 MeV uncertainty (stat) on mtop From Frank Simon, presented at 7th TLEP-FCC-ee workshop, CERN, June 2014

  21. A Sample of Essential Quantities:

  22. Theoretical limitations FCC-ee R. Kogler, Moriond EW 2013 SM predictions (usingother input) 0.0005 0.0001 0.0005? 0.0005 - 0.001 0.0000 0.0005? 0.000003? 0.000003 0.000001 0.000001? 0.000002 0.000000 Experimentalerrors at FCC-eewillbe 20-100 times smallerthan the presenterrors. BUT canbetypically 10 -30 times smallerthanpresentlevel of theoryerrors Will requiresignificanttheoreticaleffort and additionalmeasurements! Alain Blondel Precision EW measurements at future accelerators

  23. The Higgs Alain Blondel Precision EW measurements at future accelerators

  24. t H Full HL-LHC Z W b  

  25. Higgs Production Mechanism in e+ e- collisions Light Higgs is produced by “Higgstrahlung” process close to threshold Production xsection has a maximum of ~200 fb TLEP:2. 1035/cm2/s  400’000 HZ events per year (2 million Higgses in 5 years) Z – taggingby 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. the 8B$ ILC

  28. This willremain the reserveddomain of the hadron colliderswith HL-LHC and FCC-hh! Alain Blondel Precision EW measurements at future accelerators

  29. Outlook Future colliderswillimprove the precision on ElectroweakPrecision Tests by one to two orders of magnitude, providing inclusive probe of the existence new, weaklycoupled, physics. HL LHC willcontribute to map the relative Higgscouplings includingttH (4%) and HHH (30%/exp?) Furtherimprovementscanbeexpected (Tevatron, LHC) for mW (5 MeV?) and mtop (500 MeV?) e+e- collidersprovide -- invisible Higgswidth and absolutecouplingnormalization at the ZH thr, -- top mass with <100 MeV precision. -- W mass at threshold and sin2 Weff Circularcollidercanimprove Z mass and width (<0.1 MeV) and mW (beamenergy calibration) and generallyprovidehigherstatistics invisible widths of Higgs and Z bosons.  anotherorder of magnitude HHH couplingwillremainabove 10% leveluntil the 100 TeVcollider. WW scatteringis best done at hadron colliders More theoreticalwork and dedicatedmeasurementswillberequired to match improving experimentalerrors! Alain Blondel Precision EW measurements at future accelerators

  30. Status of Tevatron W mass PRL 108 (2012) 151803 PRD 89 (2014) 072003 • CDF and DØ have world’s most precise measurements based on 20% and 50% of their data → 1.1M and 1.7M Ws, resp. • MT is the most sensitive single variable, lepton PT and MET used also • Precision lepton response (0.01%) and recoil models (1%) built up from Z dileptons, Z mass reproduced to 6X LEP precision • MW precision: • CDF 19 MeV, • DØ 23 MeV, • LEP2 33 MeV • 2012 world average: 15 MeV

  31. Prospects for Tevatron W mass arxiv:1310.6708 projected • Largest single uncertainties are stat. and PDF syst. • 2X PDF improvement and incremental improvement elsewhere results in 9 MeV projected final Tevatron precision • <10 MeV precision is well motivated to further confront indirect precision (11 MeV)

  32. Prospects for LHC W mass Phys.Rev.D83: 113008,2011 • The LHC has excellent detectors and semi-infinite statistics and thus has a good a priori prospect for a <10-MeV measurement • Biggest three obstacles to surmount: • PDFs: sea quarks play a much stronger role than the Tevatron. Need at least 2X better PDFs. • Momentum scale • Recoil model/MET arxiv:1310.6708

  33. Higgs factory performances Precision on couplings, cross sections, mass, width,Summary of the ICFA HF2012 workshop (FNAL, Nov. 2012) arxiv1302:3318 (as available at the time) Couplingmeasurements @HL-LHC precision1-4%with 3000 fb-1 Circular Higgs Factory precision at few permil level. LC addsInv + total widthsat % level

  34. NB without TLEP the SM line would have a 2.2 MeV width in otherwords .... ()=  610-6 +several tests of sameprecision

  35. 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  absoultenormalization

  36. Example (fromLangacker, Erler PDG 2011) ρ=1=(MZ) . T 3=4 sin2θW (MZ) . S From the EW fit ρ= 0.0004+0.0003−0.0004 -- is consistent with 0 at 1 (0= SM) -- is sensitive to non conventionalHiggs bosons (e.g. in SU(2) triplet with ‘funnyv.e.v.s) -- is sensitive to Isospin violation such as mt  mb Measurementimplies Alain Blondel Precision EW measurements at future accelerators

  37. Similarly Wouldbe sensitive to a doublet of new fermions whereLeft and Right have different masses etc… (neutrinos are alreadyincluded) Note thatoften EW radiative corrections do not decouplewith mass => a verypowerfultool of investigation Dr = a /p (mtop/mZ)2 - a /4p log (mh/mZ)2 e3 = cos2qwa /9p log (mh/mZ)2 dnb=20/13 a /p (mtop/mZ)2 Alain Blondel Precision EW measurements at future accelerators

  38. Back to the future 30 yearslater and withexperiencegained on LEP, LEP2 and the B factories wecanpropose a Z,W,H,tfactoryof many times the luminosity of LEP, ILC, CLIC CERN islaunching a 5 years international design study of CircularColliders 100 TeV pp collider (FCC-hh) and high luminositye+e- collider (FCC-ee) IHEP in China isstudyingCEPC a 50-70 km ring, e+e- Higgsfactoryfollowed by HE pp.

  39. NB QED! @ Z pole amount for 0.3.MeV on mZ LHC  5 MeV (0.1) 0.15 0.1 1.5 1.8 Alain Blondel Precision EW measurements at future accelerators

  40. Higgs Physics with e+e- colliders above 350 GeV? 1. Similar precisions to the 250/350 GeV Higgs factory for W,Z,b,g,tau,charm, gamma and total width. Invisible width best done at 240-250 GeV. 2. ttHcoupling possible withsimilarprecision(2% full ILC) as HL-LHC (4%) 3. Higgs self couplingalsoverydifficult… precision ~20% at 1 TeVsimilar to HL-LHC prelim. estimates (30% eachexp) 10-20% at 3 TeV (CLIC)  percent-levelprecisionneeds 100 TeV pp machine  For the study of H(126) alone, and given the existence of HL-LHC, an e+e- colliderwithenergyabove 350 GeVis not compelling w.r.t. one working in the 240 GeV – 350 geVenergy range.  The stronger motivation for a high energye+e- colliderwillexist if new particlefound (or inferrred) at LHC, for whiche+e- collisions wouldbringsubstantial new information

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