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Particle Physics - High Energy Physics. High energy particles have extremely small wavelengths and can probe subatomic distances: high energy particle accelerators serve as super-microscopes.
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Particle Physics - High Energy Physics • High energy particles have extremely small wavelengths and can probe subatomic distances: high energy particle accelerators serve as super-microscopes. • The higher the energy the closer particles can come to each other, revealing the smaller details of their structure. • The energy of the collisions produces new particles : E=mc 2 The higher the energy the heavier the new particles that can be created.
and getting a bulldozer out like smashing two cars together
21st century particle physics (e.g.) Fermilab’s Tevatron is the highest energy accelerator in the world today. Beams of protons collide with beams of antiprotons
antimatter • particle accelerators create antimatter by smashing high energy particles onto metals • the total amount of antimatter produced in particle accelerators per year ~ 1 microgram • even one microgram of antimatter would provide enough energy to drive your car for a month (E=mc2)
The SNO detector is more than a mile underground no mass? • Yes, photons are massless • We thought neutrinos were massless too • In 1998 underground experiments discovered that neutrinos have tiny masses
32? 7? extra dimensions? 6? Experimentscan actually discover them! String theory demands extra dimensions.
detection of high energy particles positron in cloud chamber
e m p Pion picture in a streamer chamber; gas glows brightly along the tracks of the particles.
Jack Steinberger “ I remember in 1949, on a bulletin board at the Princeton Institute for Advanced Study, a photomicrograph of a nuclear emulsion event, showing what is now known a a K-meson decaying into three pions. We all saw it. No doubt that something interesting was going on, very different from what was then known, but it was hardly discussed because no one knew what to do with it”
Lawrence and Livingston built the first cyclotron in 1932. It was about 30 cm across, in a magnetic field of about 5000 Gauss and accelerated protons to roughly 1.2 MeV Cyclotron • 1st circular accelerator • (11 inches!) • uses both electric and magnetic fields. • particles orbit in circles
Synchro-cyclotron, Betatron, synchrotron Lawrence McMillan LBL
Cosmotron 3 GeV protons Brookhaven National Laboratory(1952)
major invasions in accelerator technology • Strong Focusing (1952) • Colliding Beams (60s) • Superconducting magnets (80s) • Stochastic Cooling (80s)
After the pion a plethora of new particles called hadronswere discovered in accelerators
fermions bosons quarks leptons gauge bosons graviton the Big picture The universe is made out of matter particles and held together by force particles
Feynman Graph The electron and quark interact electromagnetically by the exchange of a photon. The lines, wiggles and vertices represent a mathematical term in the calculation of the interaction.
Quantum Weirdness • The interactions of particles obey the rules of quantum mechanic and of special relativity • And particles aren’t really particles, they are quantum fields • The fermions (quarks and leptons) are especially weird… demo
What is a model? the Model • After 50 years of effort, we have a quantum theory which explains precisely how all of the matter particles interact via all of the forces — except gravity. • For gravity, we still use Einstein’s General Relativity, a classical theory that has worked pretty well because gravity effects are so weak.
the Standard Model • a list of particles with their “quantum numbers”, • about 20 numbers that specify the strength of the various particle interactions, • a mathematical formula that you could write on a napkin.
LEPTONS R R R L L L QUARKS L L L R R R GAUGE BOSONS g Higgs Graviton
R R R L L L QUARKS L L L R R R GAUGE BOSONS g Higgs Graviton
R R R L L L L L L R R R GAUGE BOSONS g Higgs Graviton
R R R L L L L L L R R R g Higgs Graviton + all antiparticles
16 orders of magnitude puzzle What kind of physics generates and stabilizes the 16 orders of magnitude difference between these two scales hierarchy of scales 10-17 cm Electroweak scale range of weak force mass is generated (W,Z) strong, weak, electromagnetic forces have comparable strengths 10-33 cm Planck scale GN ~lPl2 =1/(MPl)2 1028 cm Hubble scale size of universe lu 1027 eV 1011 eV 10-33 eV
what’s up with that? unification of couplings The gauge couplings of the Standard Model converge to an almost common value at very high energy.
what does the Standard Model explain ? your body atoms electrons protons, neutrons quarks
what does the Standard Model not explain ? • quantum gravity HST image of an 800 light-year wide spiral shaped disk of dust fueling a 1.2x10^9 solar mass black hole in the center of NGC 4261
what does the Standard Model not explain ? • quantum gravity • dark matter and dark energy
what does the Standard Model not explain ? • quantum gravity • dark matter and dark energy • Higgs Arrange it so delicately that it will fall down in 19 minutes.
the Bigger Big picture The Standard Model describes everything that we have seen to extreme accuracy.
the Bigger Big picture strings (even) extra dimensions supersymmetry Now we want to extend the model to higher energies and get the whole picture For this we need new experiments and ideas
Dirac (1928) matter antimatter special relativity & quantum mechanics
supersymmetry (SUSY) fermions bosons every particle has a superpartner particle
supersymmetry fermions bosons every particle has a superpartner particle
most of the dark matter in the universe maybe the lightest sparticle supersymmetry fermions bosons electron selectron quark squark photinophoton gravitinograviton • none of the sparticles have been discovered yet
For MSUSY=1 TeV, unification appears at 3x1016 GeV unification of couplings • SUSY changes the slopes of the coupling constants
