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Higgs Factory Workshop Fermilab , 14-16 Nov.2012

Higgs Factory Workshop Fermilab , 14-16 Nov.2012. The Higgs Boson Discovery. 4 th July 2012 Discovered Higgs-like Boson : Clear mass peak in gg and ZZ* 4 l I s this the SM one ? From searches to measurements. CMS HCP Nov’12. CMS. observed: 6.9; expected: 7.8. 2.

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Higgs Factory Workshop Fermilab , 14-16 Nov.2012

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  1. HiggsFactory Workshop Fermilab, 14-16 Nov.2012

  2. The Higgs Boson Discovery 4th July 2012 Discovered Higgs-like Boson: Clear mass peak in gg and ZZ*4l Is this the SM one ? From searches to measurements CMS HCP Nov’12 CMS • observed: 6.9; expected: 7.8 2 F.Cerutti - Higgs Factory

  3. LHC has donebetterthanprojected: hereis a plot from ATLAS in 2005, expected ~4with 10fb-1 at 14TeV • HCP 2012 (Kyoto): • -- mass (125.90.4 GeV/c2) (myaverage) • -- spin parity (0+ preferredat 2.45 -- CMS) alreadymeasuringcouplingsat20% level … (with a number of assuptions) gH-gluon =g gSMH-gluon fermion Vector boson Photon

  4. WhenmHisknown the EW precisionmeasurements have no more freedom! • EW precisionmeasurements, rare decays (BS, etc… ) • -- 4th generation • -- SUSY • -- Higgs triplets • -- etc. etc. • Strongincentive to revisit and improve Z pole measurements and mW…

  5. The questions Is this the Standard Model Higgs? A Higgs beyond the SM? Measure the properties of this new particle with high precision yourBanker’s question: Whatprecisionisneeded to seesomethinginteresting?

  6. Once the Higgs boson mass isknown, the Standard Model isentirelydefined. -- with the notable exception of neutrino masses, nature & mixings ***the only new physicsthereis*** 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 seesomethinginteresting?

  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 discoveries/(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  absoultenormalization

  9. Conclusions HL-LHC 3000 fb-1 at 14 TeV: • Higgs mass at 50 MeV • More precise studies of Higgs CP sector • Couplings rel. precision/Exper. • Z, W, b, t, t, m 2-10% • ggandgg2-5% • HHH >3 s observation (2 Exper.) Assuming sizeable reduction of theory errors Approved LHC 300 fb-1 at 14 TeV: • Higgs mass at 100 MeV • Disentangle Spin 0vsSpin 2 andmain CP component in ZZ* • Coupling rel. precision/Exper. • Z, W, b, t 10-15% • t, m 3-2 sobservation • ggandgg 5-11% LHC experiments entered the Higgs properties measurement era: this is just the beginning ! LHC Upgrade crucial step towards precision tests of the nature of the newly-discovered boson F.Cerutti - Higgs Factory

  10. 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

  11. HL-LHC will already be a Higgs factory, able to perform precise measurements on the relative values of the , gluon-gluon,tt, bb, , , W and Z couplings. and even some hint (30% or 3) of Higgs self-coupling. • Missing : absolute value of the Higgs total width (or overall strength of couplings) which could play against possible invisible or exotic decay mode in (fortuitous) cancellation. • Precision not sufficient for sensitivity to TeVscale in Higgscouplings 2030 2021 2 values of expectederrors: 1. assume sameanalysis and systematics 2. assume theorysystematicswillreduce by 2 and experrors as 1/sqrt(N) recall :LEP reduced by factor 10 severaltheorysystematics

  12. t H Full HL-LHC Z W Relative b  

  13. HiggsFactoriesDreams

  14.  collider

  15. m+m-Collider vse+e-Collider ? • 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 cm-2s-1 • Expect 2300 Higgs events in 100 pb-1/ year • Using g-2 precession, beam energy and energy spectrum • Can be measured with exquisite precision (<100 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 : [16,17] , W, … , W, … s (pb) √s s(mH), TLEP HF2012 : Higgs beyond LHC (Experiments)

  16. MICE Neutrino Factory MICEis one of the critical R&D experiments towards neutrino factories and muon colliders With the growing importance of neutrino physics + the existence of a light Higgs (125 GeV) physicscouldbeturningthiswayveryfast! Cooling and more generally the initial chain capture, buncher, phase rotation and cooling rely on complexbeamdynamics and technology, such as High gradient (~>16 MV/m) RF cavitiesembedded in strong (>2T) solenoidalmagneticfield MANY CHALLENGES! MUON COOLING  HIGH INTENSITY NEUTRINO FACTORY HIGH LUMINOSITY MUON COLLIDER

  17. COOLING -- Principleisstraightforward… Longitudinal: Emittance exchange involvesionization varying in spacewhich cancels the dispersion of energies in the beam. This canbeused to reduce the energyspread and is of particularinterest for + -  H (125) since the Higgsisverynarrow (~4.2 MeV)

  18. COOLING -- Principleisstraightforward… Longitudinal: Transverse: Similar to radiation damping in an electronstorage ring: muon momentumisreduced in all directions by goingthroughliquidhydrogenabsorbers, and restoredlongitudinally by acceleration in RF cavities. Thus transverse emittance isreducedprogressively. Because of a) the production of muons by pion decay and b) the short muon lifetime, ionizationcoolingisonlypractical solution to producehighbrilliance muon beams Emittance exchange involvesionization varying in spacewhich cancels the dispersion of energies in the beam. This canbeused to reduce the energy spread and is of particularinterest for + -  H (125) since the Higgsisverynarrow (~5MeV) Practicalrealizationis not! MICE coolingchannel (4D cooling) 6D candidate coolinglattices

  19. The Higgswasbarelymissedat LEP2 LEP2: 26.7km circumference 4 IPs : L3, ALEPH, OPAL DELPHI 20MW of synchrotron radiation (scales as E4/R) * = 5cm  luminositylifetime ~ few hours L = 1032 /cm2/s H=20%; 240fb 50 Higgses per exp per year! able to do discovery, but not study! Whatelse?

  20. 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

  21. CLIC Layout at 3 TeV 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 Goal: Lepton energy frontier Drive Beam Generation Complex Main Beam Generation Complex D. Schulte, CLIC, HF 2012, November 2012

  22. Latestreference: The Higgsat a Linear e+e- Collider has been studied for manyyears Communityis large and wellorganized At a givenEcm and Luminosity, the physics has marginally to do with the factthat the colliderislinear --specifics: e- (80%) and e+ (30%) polarizationiseasyat the source for ILC (not critical for Higgs) verysmallbeams verysmallbeam pipe (b and c physics) pulsedat 5-10Hz  can pulse detector and save on coolingneed (X0) Luminositygrows as ECM , 1-2 1034/cm2/s at 500 GeV, one IP. costgrows as A+BECM, both A and B are very large. ‘ready’.10 yearsfromapproval to operation  start 2025… if all goesverywell

  23. Higgs production mechanism Assuming that the Higgs is light, in an e+e– machine 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

  24. best for tagged ZH physics: Ecm= mH+11110 W. Lohmann et al LCWS/ILC2007 take 240 GeV.

  25. 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+

  26. New: 250 GeV (HZ) allows to disentangle ambiguity (intrinsic to LHC) between invisible width and total width +precisionbetter to HL-LHC in bb andcc highenergy running allowsHvvchannel +access to ttH and HHH… … not betterthan HL-LHC Can wegetsub-% precision sensitivity to TeV new physics?

  27. t H Full HL-LHC Z W b  

  28. How can one increase over LEP 2 (average) luminosity by a factor 500 withoutexploding the power bill? Answeris in the B-factory design: a verylow vertical emittance ring with higherintrinsicluminosity electrons and positrons have a muchhigher chance of interacting  muchshorterlifetime (few minutes)  feedbeamcontinuouslywith a ancillaryaccelerator

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

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

  31. TLEP tunnel in the KEK area? SuperTRISTAN in Tsukuba: 40 km ring Proposal by K. Oide, 13 February 2012

  32. 80 km ring in KEK area 12.7 km KEK

  33. 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)

  34. 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

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

  36. Circular machine revisitedaftersuper-b and synchrotron light source: e.g. TLEP  sub % precision and sensitivity to TeV-scalephysics.

  37. gHZgHbgHcgHggHWgH gH gH H H,inv

  38. LEP3, TLEP(e+e- -> ZH, e+e- →W+W-, e+e- →Z,[e+e-→t ) key parameters at the Z pole repeating LEP physics programme in a few minutes…

  39. Circular e+e Collider as a Higgs Factory • Advantages: • At 240 GeV, potentially a higher luminosity to cost ratio than a linear one • Based on mature technology and rich experience • Some designs can use existing tunnel and site • More than one IP • Tunnel of a large ring can be reused as a pp collider in the future • Challenges: • Beamstrahlung limiting beam life time requires lattice with large momentum acceptance • RF and vacuum problem from synchrotron radiation • A lattice with low emittance • Efficiency of converting wall power to synchrotron radiation power • Limited energy reach • No comprehensive study; design study needed. ICFA workshop on HiggsFactories, Fermilab 14-16- November 2012

  40. beamstrahlung:reducing * and increasing current leads to radiation of particles in the field of the colliding bunch.  increase energy spread and produce tails luminosity spectrumLEP3 & ILC: LEP3 beamstrahlung more benign than for linear collider M. Zanetti (MIT)

  41. circular HFs – beamstrahlung • simulation w 360M macroparticles • t varies exponentially wenergy acceptance h • post-collision E tail → lifetime t TLEP at 240 GeV: TLEP at 350 GeV: t>2 s at h=1.0% (4 IPs) t>37 s at h=1.5% t>11 min at h=2.0% t>3h at h=2.5% t>6 s at h=2.0% (4 IPs) t>37 s at h=2.5% t>3 min at h=3.0% t>20 min at h=3.5% M. Zanetti (MIT)

  42. Extension possibilities • 1. LEP3 (C=27km) islimited to the ZH thresholdat 240 GeV • + complicated (and unlikely) to integrate in the LHC tunnel •  keepit as backup if all elsefails • 2. TLEP (C=80km) is the favorite: • superbphysics performance, revisit all EW energyscale 90-370 GeV. • with up to 4 collision points • 80km ring e+e- collidercanbe 1st step to O(100 TeV) pp collider, • and ~100GeV<-> 50 TeVepcollider • therebyofferinglong term vision at CERN • 3. linear machines canbeupgraded to energies up to ~1 or even 3 TeV • (upgrade pathfrom ILC to CLIC in same tunnel has been discussed) • 4. A muon colliderremains the mostpromising option for the veryhigh • energy exploration with point-likeparticles.

  43. possible long-term strategy Zimmermann TLEP (80 km, e+e-, up to ~370 GeV c.m.) PSB PS (0.6 km) SPS (6.9 km) LHC (26.7 km) VHE-LHC (pp, up to 100 TeVc.m.) same detectors? (E. Meschi) also: e± (100 GeV) – p (7 & 50 TeV) collisions ≥50 years of e+e-, pp, ep/A physics at highest energies

  44. all of thisis for TLEP/VHE-LHC

  45. Conclusions -- The newlydiscovered H(126) candidate is a fascinatingparticle of a new nature (elementaryscalar!) thatdeservesdetailedmeasurements -- There ismuch more to understand about Higgsphysicsmeasurements and theirpotential to test physicsbeyond the SM. This shouldbediscussed in a dedicated and detailedHiggsPhysics workshop. -- LHC is/willbe an impressive Higgsfactory. This must betakenintoaccount in any future machine discussion! -- The linearcollider ILC canperformmeasurementsat few% level for the Higgs invisible width, search for exoticdecays, and improvement of bb, cc, couplingswrt LHC by factors ~2 -- for , , , ttH, HHH, HL-LHC will do ~ as well or better -- There is a strong motivation to investigate if one could do better -- more precise or/and cheaper -- Nowthat the Higgs mass isknown, a new round of precision EWRC measurementsisstronglymotivated. (Predictedmtop, mHiggs, now sensitive inclusively to EW-coupled new physics)

  46. Conclusions(2) • -- e+e- ring collideroffer a potentiallybetterluminosity/cost ratiothan the linear one and the possibility to have severalIPs. • -- Much progress has been brought about by the experience of LEP2 • B factories and Synchrotron light sources. • -- The main point of the HF2012 workshop was to understandwhether the performance of circular machines couldbe as high as advertised • The answeris ‘maybe’ but thereis lots of work to do to establishthis. • There are alsoideas to push the luminosityfurther. • This calls for a design study of circular e+e- HiggsFactory • -- If the luminositiesadvertisedcanbereached, the resolutions • on severalHiggscouplingscanbeimprovedfrom a few % to below percent precisions, opening the possibility of discovery of TeVscale new physics. • -- Revisiting Z pole and W thresholdisnow a must. This canbedoneatbothcircular machines withextremeprecisionusing the virtues of excellent calibration and polarization.

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