0. Einführung Einige interessante Aspekte der in der Zielsetzung genannten Fragestellungen. Appetithappen -> Antworten spaeter in der Vorlesung. Folien auf Englisch (aus anderer Vorlesung ausgeliehen) -> sorry. Muendlich auf Deutsch. Weitere Teile der Vorlesung auf Deutsch. 25.10.06 A. Geiser, Was bedeutet Masse? 1
History of basic building blocks of matter motivation: find smallest possible number ΣΛ 0 + π + ο + pω + Κ π ο πκ 0 Κ + + Supersymmetry AD 25.10.06 A. Geiser, Was bedeutet Masse? 2
The Mystery of Mass upu d down c charm s strange t top. ν e e-neutrino e electron. ν µ µ-neutrino µ muon. b bottom ν τ τ-neutrino 25.10.06 A. Geiser, Was bedeutet Masse? 3 τtau
Fermion Mass from Higgs field? very brilliant scientist (fermion) works with speed of light! -> massless room = vacuum people = Higgs vacuum expectation value 25.10.06 A. Geiser, Was bedeutet Masse? 4
Fermion Mass from Higgs field? scientist becomes famous! enters room with people 25.10.06 A. Geiser, Was bedeutet Masse? 5
Fermion Mass from Higgs field? people cluster around him hamper his movement/working speed -> he becomes massive! 25.10.06 A. Geiser, Was bedeutet Masse? 6
Quantum Numbers and Mass 1948: discovery of muon same quantum numbers as electron, except mass I.I. Rabi (Nobel 1944) Who ordered THAT? (Nobel 1988) muon decay: µ - -> ν µ e - ν e conservation of electric charge -1 0-1 0 Leon M. Melvin Jack Ledermann Schwartz Steinberger lepton number: 1 1 1-1 ν = ν (1955) muon number : 1 1 0 0 ν µ = ν e (1962) There is a distinct neutrino for each charged lepton 25.10.06 A. Geiser, Was bedeutet Masse? 7
Mass vs. structure of the proton E ~ MeV resolve whole proton static quark model, valence quarks (m ~ 350 MeV) Jerome I. Friedmann Henry W. Kendall (Nobel 1990) Richard E. Taylor E ~ m p ~ 1 GeV resolve valence quarks and their motion E >> 1 GeV resolve quark and gluon sea 25.10.06 A. Geiser, Was bedeutet Masse? 8
Inside the proton Low Q 2 (large λ) Medium Q 2 (medium λ) Heisenberg s UP allows gluons, and qq pairs to be produced for a very short time. Large Q 2 (short λ) At higher and higher resolutions, the quarks emit gluons, which also emit gluons, which emit quarks, which. At highest Q 2, λ ~ 1/Q ~ 10-18 m 25.10.06 A. Geiser, Was bedeutet Masse? 9
The Forces in Nature at ~ 1 GeV 25.10.06 A. Geiser, Was bedeutet Masse? 10
Screening of Electric Charge and Mass electric charge polarises vacuum -> virtual electron positron pairs virtual pairs partially screen electron charge and mass (Nobel 1965) effective charge/force/mass decreases at large distances/low energy (screening) increases at small distance/large energy Sin-Itoro Julian Richard P. 25.10.06 A. Geiser, Was bedeutet Masse? 11 Tomonaga Schwinger Feynman
Anti-Screening of Coulour Charge/Mass! quark-antiquark pairs -> screening gluons carry colour -> gg pairs -> anti-screening! confinement asymptotic freedom 1/r 2 ~E 2, 25.10.06 A. Geiser, Was bedeutet Masse? 12
The power of symmetries: Parity Will physical processes look the same when viewed through a mirror? In everyday day life: violation of parity symmetry is common natural : our heart is on the left spontaneous : cars drive on the right (on the continent) What about basic interactions? Eugene Wigner (Nobel 1963) Electromagnetic and strong interactions conserve parity! 25.10.06 A. Geiser, Was bedeutet Masse? 13
The power of symmetries: Parity Lee & Yang 1956: weak interactions violate Parity experimentally verified by Wu et al. 1957: Chen Ning Yang spin consequence: neutrinos are always lefthanded! (antineutrinos righthanded) 25.10.06 A. Geiser, Was bedeutet Masse? 14 (Nobel 1957) Tsung -Dao Lee Chieng Shiung Wu
How much do Neutrinos weigh? Standard Model has m ν = 0 -> evidence for m ν = 0 + parity violation forces nothing? or almost nothing? 25.10.06 A. Geiser, Was bedeutet Masse? 15
Neutrinos in Cosmology artist s view of the Big Bang ~400 ν s / cm 3! dark matter?? 25.10.06 A. Geiser, Was bedeutet Masse? 16
Why do we need colliders? early discoveries in cosmic rays, but need controlled conditions Mont Blanc m = E c 2 need high energy to discover new heavy particles colliders = microscopes LEP/LHC 25.10.06 A. Geiser, Was bedeutet Masse? 17 CERN
Weak Interactions The Theory of GLASHOW, SALAM and WEINBERG ~ 1959-1968 (Nobel 1979) Theory of the unified weak and electromagnetic interaction, transmitted by exchange of intermediate vector bosons 25.10.06 A. Geiser, Was bedeutet Masse? 18
Discovery of the W and Z (1983) To produce the heavy W and Z bosons (m ~ 80-90 GeV) need high energy collider! 1978-80: conversion of SPS proton accelerator at CERN into proton-antiproton collider challenge: make antiproton beam! success! -> first W and Z produced 1982/83 (Nobel 1984) Z 0 -> e + e - UA1 Carlo Rubbia Simon van der Meer 25.10.06 A. Geiser, Was bedeutet Masse? 19
The Quest for the Higgs at LHC Higgs production: LEP Higgs decay: depending on mass, Higgs might be found within first year of LHC physics operation! 25.10.06 A. Geiser, Was bedeutet Masse? 20
The Quest for Unification of Forces Electroweak Unification Grand Unified Theories? Maxwell s equations Superstring Theories? electric magnetic strong Big Bang weak gravity 25.10.06 A. Geiser, Was bedeutet Masse? 21
Cosmology increasing energy -> going further backwards in time in the universe -> getting closer to the Big Bang What do we know about the Mass of the Universe? 25.10.06 A. Geiser, Was bedeutet Masse? 22