Quarks, Leptons, Bosons, the LHC and all that.Some HE Physicist PrinciplesThe Standard ModelSlide 4Why High Energy?Unification of the ForcesSlide 7FermilabFermilab Makes Top QuarksThe Large Hadron ColliderSlide 11Inside the TunnelSlide 13ATLAS Detector at CERNATLAS is VERY BIGATLASWho Is ATLAS?ATLAS, The MovieSome of What LHC Can StudyLet’s Pick TwoWhat is “The Higgs”?F=MaFinding the HiggsSlide 24Supersymmetry (SUSY)Why is this an attractive idea?Dark MatterDark Matter’s EverywherePhysics 211A Simulated SUSY EventAbout Those Black Holes…About Black HolesSlide 33Slide 34Final WordsQuarks, Leptons, Bosons, the LHC and all that.Tony LissOLLI LectureSeptember 23, 2008Some HE Physicist Principles•We are reductionists (and proud of it!)–Our worldview is that there are a small number of fundamental constituents, interacting via a small number of forces, that make up the Universe as we know it.–This picture has worked extremely well for about 2000 years.–The modern version has been untangled using particle beams of ever increasing energy.????The Standard ModelThe matter around us is made up of “quarks” and “leptons”And held together by four forces, each with a force carrier:A proton is made of u u dAdd an electron to make a hydrogen atomElectromagneticStrongWeakGravityThe Standard ModelThe matter around us is made up of “quarks” and “leptons”particleadventure.orgThe marriage of quantum mechanics and special relativity required that antiparticles exist.Helium AtomWhy High Energy?•From quantum theory we know ~ 1/p Wavelength is inversely proportional to momentumIf you want to see small things you need short wavelengths (that’s why electron microscopes were invented) and short wavelengths means high momentum (and energy).•From relativity we knowE=Mc2If you want to create a heavy particle (large M) you need a lot of energy.Unification of the ForcesElectricMagneticWeakStrongElectromagneticElectroweak“Low Energy”“High Energy”“Very (very)High Energy”Theory works up to ~hereThat’s the region we want to probe with the LHC.Part way to Einstein’s dream!Higgs Bosons born here?CERN- LHCFermilab Protons & anti-protons collide at 2 TeV (2 x 1012 electron volts)The worlds highest energy particle accelerator!!Fermilab Makes Top QuarksThe heaviest known elementary particle.Discovered in 1994!Why is it so heavy??We don’t knowpp tt�eW b e bn- -�W b udb+�The Large Hadron ColliderThe world’s largest, highest energy, accelerator 300 feet underground outside of Geneva, Switzerland. The LHC collides intense beams of protons 40 million times per second at “14 TeV”2.7miFranceSwitzerlandGrapes CowsInside the TunnelATLAS Detector at CERNATLAS is VERY BIGATLASWho Is ATLAS?•ATLAS is one of four large experiments at LHC–The ATLAS collaboration consists of•~2500 physicists including•~700 graduate students from•169 different institutions in•37 different countriesATLAS is a United Nations of particle physics.ATLAS, The Moviehttp://atlas.chSome of What LHC Can Study•Higgs Boson–Understanding M•Supersymmetry–Dark Matter?•Extra Dimensions–Quantum Gravity/String Theory•Dark Energy–We don’t even know how to look for this•Heavy gauge bosons–New forces?•Precision top quark studies–New physics?•Diboson production–From the Higgs?•Quark and lepton substructure–Are fundamental particles fundamental?•etc. etc.Let’s Pick Two•Higgs Boson•SupersymmetryWhat is “The Higgs”?•Named after Peter Higgs•It “gives mass” to the fundamental particles (if, in fact, it exists)Without the Higgs (or something) the theory requires that all these fundamental particles have M=0. But we know that’s not the case.F=MaThe idea is that the Higgs field exists throughout all space. As particles try to move through this field they interact with it and are “slowed down”. Heavier particles are those that interact more stronglyM=F/aIn quantum mechanics there is a particle associated with a field (quantum of the field). The photon is the quantum of the electromagnetic field. The Higgs boson is the quantum of the Higgs Field.Finding the Higgs•The Higgs “couples to mass”–It decays to the heaviest particles availableEasy, but rareHard, but copiousThis is a simulation of the production and decay of a Higgs to two Z bosons.The Z bosons themselves decay, one to a pair of electrons and the other to a pair of muons.0 0 0pp H Z Z� �e+e-+-Supersymmetry (SUSY)•Every quark, lepton and force carrier has a SUSY partner (sparticles).–Sparticles would be made copiously in the early (HOT) universe.–They all decay away quickly, except for the lightest one (neutralino), which has nowhere to go.www.science.doe.gov/hep/EME2004/03-what-is.htmlMake SUSY particles at an accelerator:pp cc�%%SUSY & Unified ForcesWhy is this an attractive idea?•SUSY helps with unifying the forces.•SUSY is a necessary ingredient of quantum gravity theories.•We know that the universe is filled with dark matter.–Dark matter is not made of quarks and leptons – the Standard Model has no dark matter candidates.–Dark matter interacts very weakly with normal matter (or else we would have found it already).–The lightest SUSY particle is a perfect candidate.•Einstein’s dream of a “Unified Field Theory”, now needs SUSY:Energy Strength of forceNo SUSYEnergy Strength of forceSUSYEMweakstrongDark MatterDark Matter’s EverywhereSpeed of stuff out hereDoesn’t match luminous matter in here!In GalaxiesMotion of a galaxy out hereDoesn’t agree with luminous matter in hereThe “Hydra” Galactic ClusterAnd clusters of galaxiesPhysics 211•Momentum is “conserved”–Before the protons collide they have equal and opposite momentum: The total momentum is zero.–Therefore: The total momentum of all the stuff created in the collision must also be zero.A Simulated SUSY EventMissing momentum carried away by invisible particleAbout Those Black Holes…•Creating microscopic black holes at the LHC would be –A MAJOR BREAKTHROUGH IN SCIENCE!–INCREDIBLY EXCITING–NOBEL PRIZE STUFF–NOT AT ALL DANGEROUS–REALLYAbout Black Holes•The microscopic black holes that might be created at LHC are so small they evaporate instantly according to Steven Hawking.–But what if Hawking’s wrong?•Cosmic rays reach much higher energies than the LHC and have been having collisions for billions of years – any black holes created have