At the end of this section, we review unification theories in particle physics. We describe the Standard Model in detail in terms of electromagnetic, weak nuclear, and strong forces. In this section, we introduce the Standard Model, which is the best current model of particle interactions. The equation itself might be complex, but many scientists suspect the idea behind the equation will make us exclaim: “How could we have missed it? It was so obvious!” The ultimate goal of physics is a unified “theory of everything” that describes all particle interactions in terms of a single elegant equation and a picture. This work builds directly on work done on gravity and electromagnetism in the seventeenth, eighteenth, and nineteenth centuries. A particle physicist seeks to develop models of particle interactions. The chief intellectual activity of any scientist is the development and revision of scientific models. Explain the rationale behind grand unification theories.Use Heisenberg’s uncertainty principle to determine the range of forces described by the Standard Model.Draw a Feynman diagram for a simple particle interaction.Describe the Standard Model in terms of the four fundamental forces and exchange particles.The necessary data will be provided in questions for particles outside those specified.Įnergy and momentum are conserved in interactions.By the end of this section, you will be able to: Properties of quarks: charge, baryon number and strangeness.Ĭombinations of quarks and antiquarks required for baryons (proton and neutron only), antibaryons (antiproton and antineutron only) and mesons (pion and kaon) only.Ĭhange of quark character in β - and β + decay.Īpplication of the conservation laws for charge, baryon number, lepton number and strangeness to particle interactions. Up (u), down (d) and strange (s) quarks only. Particle physics relies on the collaborative efforts of large teams of scientists and engineers to validate new knowledge. Strangeness can change by 0, +1, or -1 in weak interactions Strangeness as a quantum number to reflect the fact that strange particles are always created in pairs.Ĭonservation of strangeness in strong interactions. Strange particles are produced through the strong interaction and decay thorugh the weak interaction (e.g. The muon as a particle that decays into an electron Leptons are subject to the weak interaction.Ĭonservation of lepton number for muon leptons and electron leptons. Leptons: electron, muon, neutrino (electron and muon types). The kaon as a particle that can decay into pions. The pion as the exchange particle of the strong nuclear force. Hadrons are subject to the strong nuclear force.Ĭandidates should know that the proton is the only stable baryon into which other baryons eventually decay the decay of the neutron should be known. Hadrons: baryons (proton, neutron) and antibaryons (antiproton and antineutron) and mesons (pion, kaon). Simple Feynman diagrams to represent the above reactions or interactions in terms of particles going in and out and exchange particles. The weak interaction limited β -, β + decay, electron capture and electron-proton collisions W + and W - as the exchange particles. The electromagnetic force virtual photons as the exchange particle. The use of E = mc 2 is not required in calculations.Ĭoncept of exchange particles to explain forces between elementary particles (knowledge of the gluon, Z o and graviton will not be tested). Knowledge of annihilation and pair production processes and the respective energies involved. There are four fundamental interactions: gravity, electromagnetic, weak nuclear, strong nuclear (the strong nuclear force may be referred to as the strong interaction) Photon model of electromagnetic radiation, the Planck constant, E = hf = λ/hc The positron, the antiproton, the antineutron and the antineutrino are the antiparticles of the electron, the proton, the neutron and the neutrino respectively.Ĭomparison of particle and antiparticle masses, charge and rest energy in MeV. That the existence of the neutrino was hypothesised to account for the conservation of energy in beta decayįor every type of particle, there is a corresponding antiparticle. The strong nuclear force its role in keeping the nucleus stable short-range attraction to about 3 fm, very-short range repulsion below about 0.5 fmĮquations for alpha decay and β - decay including the need for the neutrino. The meaning of isotopes and the use of isotopic data Proton number Z, nucleon number A, nuclide notation Simple model of the atom: Proton, neutron, electron their charge and mass in SI units and relative units. Back to Teaching Rota Particle Physics - Objectives

Electron capture feynman diagram