wan ahmad tajuddin wan abdullah jabatan fizik universiti malaya Quantum fields wan ahmad tajuddin wan abdullah jabatan fizik universiti malaya

Special relativity c as limitting velocity Time is relative Spacetime – Lorentz invariance Locality - no action at a distance

Quantum mechanics Wave-particle duality Uncertainty principle Measurement – wave function collapse - entanglement

Relativistic quantum mechanics Non-relativistic: Schroedinger equation Relativistic: Klein-Gordon equation non-linear! Linearize: SPIN  ANTIPARTICLES Dirac equation

Fields Force as fields – Gravitational [Newton’s gravitational law] Electromagnetic [Maxwell’s equation] Extended in space Action at a distance

Quantum fields waves ~ particles potentials ~ virtual particles Absolute values at every point in space  probabilistic distribution of values (from virtual particles) at every point in space Absorption/scattering of virtual particles  “force”

Path integrals Classical mechanics – trajectories Euler-Lagrange equation Langrangian extremise ‘action’ least action principle Quantum paths probability amplitude

Feynman diagrams Diagrammatic representation Facilitate calculations – Feynman rules

Perturbation theory Lowest order approximation – lowest order diagrams (least number of vertices) Higher order – include higher order diagrams                         Theory         gs = 2.002319282                         Experiment       gs = 2.002319288                                                     + 0.000000014 drawing by Tom Brown

Quantum field theory of fundamental forces Gauge fields (bosons) mediating interactions – EM – photons Weak nuclear force – W, Z bosons Strong nuclear force – gluons GAUGE SYMMETRY between fields UNIFICATION of forces into bigger symmetry

Higgs Spontaneous symmetry breaking Give masses to particles Higgs particle