option j: particle physics j1 particles and interactions

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Option J: Particle physics J1 Particles and interactions. This part of Option J has already been covered in Option D4 Particles and interactions . It is replicated here without any changes. Option J: Particle physics J1 Particles and interactions. - PowerPoint PPT Presentation

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  • Option J: Particle physicsJ1 Particles and interactionsThis part of Option J has already been covered in

    Option D4 Particles and interactions.

    It is replicated here without any changes.

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesJ.1.1State what is meant by an elementary particle.J.1.2Identify elementary particles.J.1.3Describe particles in terms of mass and various quantum numbers. J.1.4Classify particles according to spin.J.1.5State what is meant by an antiparticle.J.1.6State the Pauli exclusion principle.

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesState what is meant by an elementary particle.An elementary particle is one which has no internal structure.PRACTICE: At one time it was thought that atoms were elementary particles. Explain why they are not.SOLUTION: They have an internal structure: Namely protons, neutrons and electrons.EXAMPLE: At one time it was thought that protons and neutrons were elementary particles. Explain why they are not.SOLUTION: Protons and neutrons are each built from three elementary particles called quarks.

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesIdentify elementary particles.There are three major divisions in the elementary particles that have been identified, to date. The force carriers are the particles that allow compatible particles to sense and react to each others presence through exchange of these carriers.The quarks are the heavier, tightly bound particles that make up particles like protons and neutrons.The leptons are the lighter, more loosely bound particles like electrons.FYIFor example, quarks interact via the strong force particles called gluons.

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesIdentify elementary particles.The force carriers:There are four force carriersINTERACTION 1: STRONG: Strongest of all the interactions between particles. We can give it an arbitrary value of 1 for comparison.INTERACTION 2: ELECTROMAGNETIC: This is the NEXT strongest. In comparison to the strong interac-tion, it has a relative strength of 10-2. INTERACTION 3: WEAK: This interaction has a relative strength of 10-6. INTERACTION 4: GRAVITATIONAL: This interaction has a relative strength of 10-39. 1.0 0.01 0.000001 0.000000000000000000000000000000000000001

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesIdentify elementary particles.The force carriers:In 1933 Hideki Yukawa developed the theory of exchange forces.The basic idea is that all forces are due to the exchange of particles between like elementary particles.Consider two protons in space.Yukawa postulated that the protons exchange photons and repel each other because of this exchange.FYIThis photon exchange is the electromagnetic force.

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesIdentify elementary particles.The force carriers:Yukawa explained that the electromag- netic force was long range (in fact infinite in range) because photons "live forever" until they are absorbed.Yukawa explained that the strong force was short range (in fact only in the nuclear range) because the strong force exchange particle (the gluon) has a very short life.LONG RANGE EXCHANGE PARTICLESHORT RANGE EXCHANGE (VIRTUAL) PARTICLE

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesIdentify elementary particles.The force carriers:The following table compares the exchange particles (force carriers) by range and mass.INTERACTIONEXCHANGE PARTICLERANGEREST MASSSTRONGGLUON g10-15 m120 MeV / c2ElectromagneticPHOTON 0WEAKW+, W- and Z10-18 m80 GeV / c2GravitationGRAVITON 0

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesIdentify elementary particles.The quarks:Although you have heard of protons and neutrons, both of which react to the strong force exchange particle (the gluon), you have probably not heard of most of the following particles:ParticleSymbolprotonpneutronndelta++delta+delta0delta-lambda0sigma+sigma0sigma-xi0omega-ParticleSymbolParticleSymbolFYIWith the advent of particle research the list of new particles became endless!

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesIdentify elementary particles.The quarks: In 1964 the particle model was looking quite complex and unsatisfying. Murray Gell-Mann proposed a model where all the strong-force particles were made up of three fundamental particles called quarks.FYIA proton is uud and a neutron is udd.QuarkFlavorUpDownStrangeCharmBottomTopSymboludscbtCharge+ 2/3- 1/3- 1/3+ 2/3- 1/3+ 2/3uudproton

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesIdentify elementary particles.The quarks: Each quark has an antiquark, which has the opposite charge as the corresponding quark.FYIBaryons are particles made up of 3 quarks or 3 antiquarks.Mesons are particles made up of a 1 quark and 1 antiquark.

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesIdentify elementary particles.The leptons:You are already familiar with two of the six leptons: the electron and the electron neutrino.Leptons, unlike quarks, do NOT participate in the strong interaction.FYIOf course the leptons also have their antiparticles.THE LEPTONSCharged LeptonsUncharged Leptonselectronemuontauelectron neutrinoemuon neutrinotau neutrino

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesIdentify elementary particles.The leptons:The leptons interact only via the electromagnetic force carrier, the photon.Leptons, unlike quarks, do not react to the gluon.Quarks react to both the gluon and the photon.FYILeptons and quarks also react to gravitons.

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesIdentify elementary particles.The Higgs particle is another particle that physicists think exists and are in search of.This particle is the one that gives quarks and leptons their mass.To date the Higgs particle has not yet been found.FYICERN and the Large Hadron Collider were developed with the Higgs boson in mind.

  • The Large Hadron Collider at CERN.

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesDescribe particles in terms of mass and various quantum numbers.

    QUARKSu (up)c (charm)t (top)Charge / e+2/3+2/3+2/3Mass / mp1/31.7186d (down)s (strange)b (bottom)Charge / e-1/3-1/3-1/3Mass / mp1/30.54.9

    LEPTONSe(electron)(muon)(tau)Charge / e-1-1-1Mass / mp0.00050.11.9e (e-neutrino) (-neutrino) (-neutrino)Charge / e000Mass / mp000

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesDescribe particles in terms of mass and various quantum numbers.Quarks have a baryon number of 1/3 and antiquarks have a baryon number of -1/3.PRACTICE: Find the baryon number of a baryon, a meson, and an electron:SOLUTION:A baryon has three quarks (or three antiquarks): For qqq we have B = +1/3 + +1/3 + +1/3 = +1. For qqq we have B = -1/3 + -1/3 + -1/3 = -1.A meson has a quark and an antiquark: For qq we have B = +1/3 + -1/3 = 0.An electron has no quarks and thus has B = 0.

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesDescribe particles in terms of mass and various quantum numbers.Leptons have a lepton number of 1 and antileptons have a lepton number of -1.PRACTICE: Find the lepton number of an electron, a positron, an anti electron neutrino, and a proton:SOLUTION:An electron has a lepton number of L = +1.A positron is an antiparticle and so has L = -1.An anti electron neutrino has L = -1.A proton is not a lepton and so has L = 0.

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesDescribe particles in terms of mass and various quantum numbers.Conservation of charge.Conservation of baryon number.Conservation of lepton number.

  • Option J: Particle physicsJ1 Particles and interactionsDescription and classification of particlesDescribe particles in terms of mass and various quantum numbers.Conservation lepton number violated.L = 0L = 0+ 1= 1.We need a particle on the right with L = -1 (an antilepton).01n 11p + -10e + eL :001-1

  • Option J: Particle physicsJ1 Particles and interactionsPRACTICE: Evaluate each reaction as "possible" or "not possible considering B, L and Q. p n + e+ + eB:L:Q: n p + e- + eB:L:Q: n + p e+ + eB:L:Q:Description and classification of particlesDescribe particles in terms of mass and various quantum numbers.110000-111010POSSIBLE1100001-101-10POSSIBLE110000-1-101

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