The International Linear Collider:The International Linear Collider:The Physics and its ChallengesThe Physics and its ChallengesHarry WeertsArgonne National LabUTA, September 20, 20062H.WeertsUTA, Sept 20, 2006R&DOutlineParticle Physics: status & futureHistory, Matter & Interactions;US program and worldwide programOpen questionsIntroduction: personal Future Program and Open Questions ILC PhysicsThe ILC : the detector challengesThe ILC: the machine challenges3H.WeertsUTA, Sept 20, 2006R&DIntro: personalHadron collider physics with Dzero experiment ( MSU, Fermilab)Since inception, >20 yearsNeeded something new before retirement……Time scales a concern in HEP“Decided” ILC needs senior involvementYoung people busy & not good for themSpent sabbatical 2004-2005 at Fermilab.Work on ILC only.Learnt a lot, machine & detectors, a lot of progress on ILC that yearTechnology decision; GDE formed, started on detector concept study, Snowmass 2005By Sept 2005:Well into ILC, also changed positions, strengthen & define ILC program at Argonne(Management & ILC)4H.WeertsUTA, Sept 20, 2006R&DState of HEP/Particle PhysicsStrong, competing & complementary accelerator based experimental programs around world:TheoryImmense progress over last 40 yearsExperimentsDynamics based on (non)-abelian, local gauge invariance, led to unification of forces: EM and weak, strongStandard Model, with detailed predictions, but also open questionsstrong feedbackFixed targetBeams: e,µ,p,π,νHigher energy: colliding beamsee, pp , ep5H.WeertsUTA, Sept 20, 2006R&DHow did we learn this…beamsprotons, muons, neutrinos,etctargetdetectorIncreasing energy probes smaller and smaller distances12Fixed TargetColliding beamsprotonelectrondetectorprotonpositronantiprotonGargamelle in neutrino beamDzero event at Tevatron6H.WeertsUTA, Sept 20, 2006R&DStatus of Particle Physics (1)All matter made up of fermions ( quarks & leptons) Interactions/forces between them mediated by bosonsUnderstood at such a level that ALL interactions/cross sections can be well calculated and simulatedVery good predictive power(verified by experiment)Described by Standard Modelat energies reachable today7H.WeertsUTA, Sept 20, 2006R&DFermions make up all known matterInteractions/Forces (more detail)Electromagnetic =Strong (QCD) =Weak =Status of Particle Physics (2)+=All of “day to day” matterNuclear reactors= neutrino industry;Flavor Oscillations8H.WeertsUTA, Sept 20, 2006R&D“Problems” with the Standard Model (I)The Standard Model predicts/requires at least one more field Î HiggsSo far not observed Î problemParticles are being searched for Îout of energy range accessible now( need for higher energy)Part of symmetry breaking, resulting in SMTo keep Higgs mass finite, avoid divergences in scattering (WW) need additional symmetries i.e. fields i.e. particlesPossible solutions:Supersymmetry (SUSY), extra dimensions, plus ++Unexplained:•Mass hierarchy•Neutrino oscillations•Matter-antimatter asymmetry in universe Missing parts(experiment: m > ~250 Gev/c)9H.WeertsUTA, Sept 20, 2006R&DProblems (2)Cosmic microwave background, rotation curves of galaxies point to need forAdditional “missing” fields/particlesAstro physical observationsAccelerated expansion of universe point to need forDark MatterDark Energy10H.WeertsUTA, Sept 20, 2006R&DObservations from universe ( large scale)Observations from universe ( large scale)Questions about universe:Where is anti matter ?Most mass in universe not in SM particles So ONLY 4% of universe consist of particles we know.A lot left to identify…..11H.WeertsUTA, Sept 20, 2006R&DState of knowledge of universe…The “Iceberg” picture of our understanding of universe.Next step is to address this at accelerators and find the corresponding particles and understand what dark matter and energy areConnect cosmic scale to particle scale12H.WeertsUTA, Sept 20, 2006R&D1990 1995 2000 2005 201019901995200020052010LEPLEP Ipb-1175 513510+10 55 175183 189 196-200161.3172SLCTevatronRun I (1.8TeV)Run II (2TeV)pb-1110HERA47 pb-1e+pe-pCESRLHC (14TeV)BaBar, Belle, HERA-B2-> 4 -> ? fb-1Run IIRHIC ppnowParticle Physics acceleratorsB factoriesLHCbInterplay needed:LEP<-> TevatronHERA<-> TevatronHERA<-> LHCTevatron <-> BabarILCfewemptyworldUS13H.WeertsUTA, Sept 20, 2006R&DThe future I; will happenThe first BIG step in understanding Higgs and “Iceberg” will theLarge Hadron Collider (LHC) at CERNWill be very difficult( impossible….) to distinguish different physics models/theories(ILC)Find new/unexplained phenomena & particlesLHCATLASMont Blanc MassifReady for 1stbeam end 2007. Detector scale 15 year programProton-proton collisions at 14 TeV; expect lots of new physics & discoveriesLHC is discovery machine14H.WeertsUTA, Sept 20, 2006R&DLHC potential and need for ILCThe Large Hadron Collider (LHC), will open window to “remainder” of and physics “beyond” the Standard Model. Completing the Standard Model and the symmetries underlying it plus their required breaking leads us to expect a plethora of new physics.This is the energy/mass regime from ~0.5Tev to a few TeVStarting in 2007…..LHC will discover them or give clear indications that they exist.new particles and fields in this energy rangeWe will need a tool to measure precisely and unambiguously theirproperties and couplings i.e. identify physics.This is an e+e-machine with a centre of mass energy starting at 0.5 TeV up to several TeVILCone pageStarting next decadeLHC15H.WeertsUTA, Sept 20, 2006R&DDifference in “energy frontier” experiments (ee)Two main kind of machines:1)electron –positron ( e+e-annihilation) colliders2)proton-(anti)proton collider ( Tevatron, future LHC)e+e-annihilation:Total energy of e+ and e-available as Ecmsor √sScan over resonancesMaximum achieved for Ecms=192 GeVVery clean environment; precision physicsEnergy range covered by e+e-colliders16H.WeertsUTA, Sept 20, 2006R&DILC: Physics Event Ratess-channel processes through spin-1 exchange: σ ~ 1/sCross sections relatively democratic: σ (e+e-→ ZH) ~ 0.5 * σ(e+e-→ ZZ)Cross sections are small; for L = 2 x 1034 cm-2s-1e+e-→ qq, WW, tt, Hx~ 0.1 event /train e+e-→ e+e-γγ → e+e-X ~ 200 /trainBeyond the Z, no resonances W and Z bosons in all decay modes become main objects to reconstructNeed to reconstruct final statesForward region critical Highly polarized e-beam: ~ 80%17H.WeertsUTA, Sept 20, 2006R&DILC Physics CharacteristicsCross sections above
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