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Stuff and Glue Particles and Forces

Stuff and Glue Particles and Forces. Experimental methods What is matter ? Which forces stabilize matter? Open questions and the next steps. Thomas Lohse Humboldt-Universität zu Berlin. fire. water. earth. air. Greek Philosophy. Empedokles ( 500-430 B.C.)

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Stuff and Glue Particles and Forces

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  1. Stuff and GlueParticles and Forces • Experimental methods • What is matter? • Which forces stabilize matter? • Open questions and the next steps Thomas Lohse Humboldt-Universität zu Berlin

  2. fire water earth air Greek Philosophy • Empedokles (500-430 B.C.) • four elements: fire, water, earth, air • two fources: love , hatred  mixing, separating • Platon(427-347 B.C.) • symmetric shapes:beauty of laws of nature • Demokrit (460-371 B.C.) • atoms:different forms and weights • emptiness:binding and motion in the void

  3. How to resolve structures? scattering of photons: eye: ~1 mm resolution lense: ~ 0.1 mm resolution light microscope: ~ 1 µm Limited by

  4. How to resolve structures? particle scattering: Rutherford scattering: E = O(MeV) α-particles λ = O(fm) gold atoms with nuclei modern particle accelerators, e.g. HERA: e(27 GeV) on p(920 GeV) resolution 0.001 fm

  5. TV tube Fermilab injector superconducting RF cavity for future linear collider TESLA the principle SLAC linac first linear collider Particle Accelerators a) linear accelerators

  6. Particle Accelerators b) storage rings

  7. LEP SPS DESY (Hamburg) CERN (Geneva ) Particle Accelerators c) the big labs in Europe

  8. Particle Detection OPAL detector at LEP, CERN display of electronic signals

  9. Myon Chambers Hadron Calorimeter e– Tracking Chamber Electromagn. Calo. Two Topologies Colliding beams (e+e–, ep, pp...) cylindrical shell structure of subdetectors

  10. hadron absorber & muon system RICH detector EM calorimeter Si-vertex detector tracking system Two Topologies Forward layer structure of subdetectors Fixed target (μ–A, pA, ...) HERA-B magnet 21 m

  11. typical impact parameters O(100 μm) 40 cm Subdetector Tasks Silicon Microstrip Wafers => vertex tracking Proportional Drift Chambers => main tracking typical coordinate resolution O(200 μm) magnetic field => particle momentum from curvature

  12. HERA-B RICH Subdetector Tasks Particle Identification: example Ring Imaging CHerenkov detectors Ring radius => p/m => π,K,p sep. light detector (e.g. PM tubes) point on Cherenkov ring mirror Cherenkov cone charged particle in radiator gas

  13. Subdetector Tasks Calorimeters (lead, steel, uranium...) electromagnetic showers => e,γ energy hadronic showers => energy of hadrons penetrating particles => muons

  14. Crystal Molecule Atom Nucleus Structure of Matter elements of normal matter: • neutrinos: from β-decay / sun burning • quarks: always bound, ”confinement“

  15. jet quark e+ e– jet antiquark How to see the quarks accelerators => high energy quarks quarks => jets of secondary hadrons

  16. e jet How to measure quarks in the proton accelerators => knock quarks out of protons final state kinematics => initial quark momentum

  17. Quantitative: proton structure functions quark densities in the proton as function of the quark momentum and the resolution of the scattering

  18. Heavier short-lived Generations High energy collisions reveal heavier versions of quarks and leptons! up ... charm ... top down ... strange ... bottom electron ... muon ... tauνe ... νμ ... ντ very strange mass spectrum...

  19. groups periods Strong Similarity to ...

  20. The Periodic System of Elementary Particles particle physics: periods = families quark/lepton periods I II III u-quark group d-quark group neutrino group electron group

  21. More Families??? LEP: lineshape of Z resonance from LEP visible invisible ΓZ = Γvis + Γinvis Γinvis = Nfam · Γν Nfam = 3 measurements:

  22. Forces: Exchange of Field Quanta repulsive attractive

  23. n n n n n n n n n S p p p p p p p p p p p N q q The Fundamental Forces (confinement)

  24. Gamma Quantum in Action γ

  25. Gluon Quantum in Action

  26. W Quanta in Action

  27. Z Quanta in Action

  28. The Complete(??) Picture

  29. Supersymmetry: still a hypothesis... Superpartners of Matter Particles Spin 0 Matter Particles Spin 1/2

  30. Supersymmetry: still a hypothesis... Superpartners of Force Particles Force Particles

  31. γ ep cross section vs. squared momentum transfer electromagnetic e W weak unification at ν Why is the Weak Force Weak? It isn‘t weak at all!!! It is just a mass effect!!!

  32. We have just seen this: Electroweak unification E = 100 GeV like 10-10s after big bang Grand electroweak/strong unification E = 1014 GeV like 10-35s after big bang Planck Scale: unification with gravity E = 1019 GeV like 10-43s after big bang A Unified Single Force?

  33. Big Bang

  34. Symmetric potential energy Initial state of the universe • Asymmetric ground state: • masses are created • a Higgs particle appears Inflation: spontaneous symmetry breaking Vacuum field strength Why such funny asymmetric masses of force particles? Hypothesis: There is a background field in the universe... the Higgs field

  35. How does Mass Creation Work? A conference banquet... The nobel prize winner enters the room... The physicists next to him turn immediately to talk to him. It becomes hard for him to move (accelerate). He is effectively massive... physicists = background Higgs field nobel prize winner = massive particle

  36. How does Mass Creation Work? A conference banquet... A rumour is injected... The physicists cluster where the rumour spreads out. It gets hard for the rumour to move (accelerate)... rumour = Higgs particle The Higgs particle is itself massive!

  37. direct search not yet successful: mH > 114 GeV Higgs mass enters via quantum corrections in precision measurements And Where is the Higgs?

  38. ? ? Open Questions • Why three families ? • Why symmetric lepton/quark structure ? • Does the Higgs particle exist ? • Why such a strange mass spectrum ? • Characteristic pattern of quark family transistions ? • Transitions in lepton family ? • Where/how is the antimatter gone ? • Supersymmetric partners of particles and fields ? • Is there a unified force ? • What about gravity ? Extra space-time dimensions? ...

  39. LHC goals: • establish the Higgs particle • search for supersymmetry • search for new effects accessible mass scale: ~1 TeV ATLAS detector The next big steps: (1) LHC / CERN LHC: 7 TeV protons on 7 TeV protons Start of operation: 2007-2008

  40. The next big steps: (2) TESLA / DESY • 33 km linear e+e–-collider, energy 500-800 GeV • Similar projects proposed by U.S.A. and Japan • start not before 2013 • TESLA goals: • detailed properties of Higgs particle • highest precision tests of electroweak force • detailed properties of supersymmetric particles • search for extra dimensions ...

  41. It stays interesting...

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