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Particle Physics Part 1 •Review: Fundamental forces and particles •Feynman diagrams •Experimental QCD •Accelerators and Detectors •Electroweak Theory Part 2 •Experimental Electroweak •Higgs searches •Top Quark •Heavy Flavour physics •Neutrinos •Beyond the Standard Model http://ppewww.ph.gla.ac.uk/~parkes/teaching/PP/PP.html Chris Parkes & Rick StDenis 1 Revision of Fundamental Particles & Forces • • • • Standard Model Fermions & Bosons Standard Model Structure Common Mesons & Baryons Natural units 2 Particle Physics Aim: Understand the fundamental particles and forces of nature. Tools: Particle colliders operating at the highest energies achievable. It involves the biggest, most complicated experiments in the history of science, with the fastest computers, the coldest temperatures and the strongest magnets on Earth. Particle physics re-creates the universe just after the Big Bang and hopes to answer the questions that humans have been asking for eternity; “Where do we come from?” “What are we made of?” 3 Some alternative reasons to study 1. I want a nobel prize! this course! 2004 – QCD 1999 – QFT 1992 -- particle detectors 1988 -- muon neutrino 2002 – neutrinos 1995 -- tau / neutrino 1990 -- Deep Inelastic Scattering 1984 -- W&Z bosons 2. I want to understand why 5000 physicist worldwide are currently building the world’s largest machine! LHC @ CERN 2 PhD places in Glasgow for Oct. 2008 •27 km long tunnel,100m underground •French/Swiss Border near Geneva •2007 onwards Large Hadron Collider (LHC), 14 TeV proton collider •Origin of mass (Higgs Boson) •New Physics (e.g. Supersymmetry) •Matter anti-matter asymmetry in Universe (CP Violation) 4 Standard Model – Particle Physics • Summarises the current knowledge • Quantum theory that includes : – unified theory of weak and electromagnetic (QED) interactions (ElectroWeak) – Strong Interactions (Quantum chromodynamics – QCD) – Does not include gravity – Includes one boson – the Higgs – which has not yet been discovered…. 5 6 + Higgs boson, spin 0, electric charge 0, mass unknown yet….. 7 Strength – see section on running coupling constants later 8 Composite particles Or where the quarks hide…. •Mesons are quark anti-quark system Integer spin particles About 140 types are known •Baryons are three quark / three anti-quark systems About 120 types are known Details of all known at http://pdg.lbl.gov/ Some common ones on the next pages 9 Light Flavour Mesons Particle Symbol Antiparticle π- Makeup Rest mass MeV/c2 Lifetime (s) Decay Modes 139.6 2.60 x10-8 μ+νμ 135.0 0.83 x10-16 2γ 1.24 x10-8 μ+νμ, π+π0 0.89 x10-10 5.2 x10-8 π+π-,2π0 0.4 x10-23 20 x10-23 π+π- Pion π+ Pion π0 Self Kaon K+ K- us 493.7 Kaon K0s K0s su 497.7 Kaon K0L K0L su 497.7 Rho ρ0 Self uu, dd 770 Phi φ Self ss 1020 ud π+e-νe K+K-10 ,K0K0 Particle Symbol Antiparticle Makeup Rest mass Lifetime MeV/c2 D D+ D- cd 1869.4 D D0 D0 cu 1864.6 D D+s D-s cs 1969 Self cc 3096.9 J/Psi J/ψ B B- B+ bu 5279 B B0 B0 db 5279 Bs Bs 0 sb 5370 bb 9460.4 Upsilon 0 ϒ Bs Self 10.6 x10-13 4.2 x10-13 4.7 x10-13 0.8 x10-20 1.5 x10-12 1.5 x10-12 ... 1.3 x10-20 Decay Modes K + _, e + _ [K,μ,e] + _ K+_ e+e-, μ+μ-... D0 + _ D0 + _ D-s + _ e+e-, 11μ+μ-.. Baryons -1 Symbol Makeup Rest mass MeV/c2 Spin Proton p Neutron n uud ddu 938.3 939.6 1/2 1/2 Lambda Λ0 uds 1115.6 1/2 Sigma Σ+ uus 1189.4 1/2 Sigma Σ0 uds 1192.5 1/2 Sigma Σ- dds 1197.3 1/2 Delta Δ++ uuu 1232 3/2 Delta Δ+ uud 1232 3/2 Particle Lifetime (seconds) Stable 920 2.6 x10-10 0.8 x10-10 6x10-20 1.5 x10-10 0.6 x10-23 0.6 x10-23 Decay Modes ... pe-νe pπ-, nπ0 pπ0, nπ+ Λ0γ nπpπ+ 120 pπ Baryons -2 Particle Symbol Makeup Rest mass MeV/c2 Spin Delta Δ0 udd 1232 3/2 Delta Δ- ddd 1232 3/2 Xi Cascade Ξ0 uss 1315 1/2 Xi Cascade Ξ- dss 1321 1/2 Omega Ω- sss 1672 3/2 Lambda Λ +c udc 2281 1/2 Lifetime (seconds) 0.6 x10-23 0.6 x10-23 2.9 x10-10 1.64 x10-10 0.82 x10-10 2x10-13 Decay Modes nπ0 nπΛ0π0 Λ0πΞ0π-, Λ0K... 13 Natural Units, =c=1 • • • • • • • • Energy GeV Momentum GeV/c (abbreviated to GeV) Mass GeV/c2 Length (GeV/c)-1 c=0.197GeVfm=1 [1fm=1E-15m] – Natural unit of length 1GeV-1=0.197fm Time (GeV/ )-1 =6.6E-25GeVs – Natural unit of time 1GeV-1=6.6E-25s Cross-section (GeV/c)-2 1barn=10-28m2 – Natural unit of xsec =1GeV-2=0.389mb Charge - ‘Heavyside-Lorenz units’ ε0=1 Use dimensionless ‘fine structure constant’ e2 e2 1 40c 4 137 14