Class27HO - Class 27 The Standard Model and General...

Info iconThis preview shows pages 1–20. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Class 27 The Standard Model and General Relativity Physics 106 Fall 2011 Press CTRL-L to view as a slide show. Last Time Last time we discussed: I Elementary Particles I Fundamental Interactions I Feynman Diagrams I New Particles Learning Outcomes Today we will discuss: I Feynman Diagrams I Particle Families I The Eight-fold Way I Quarks and the Standard Model I Cosmology and General Relativity Conservation Laws Conservation Laws I Conservation of baryon number I Conservation of lepton number and three separate types of lepton numbers: I Conservation of electron number I Conservation of muon number I Conservation of tau number I Conservation of strangeness Conservation of Baryon Number I Assigning baryon number: I B = 1 for baryons I B =- 1 for antibaryons I B = 0 for all other particles I Whenever a baryon is created an antibaryon is also created Conservation of Electron Number I Assigning electron number: I L e = 1 for the e- and the electron neutrino, e I L e =- 1 for the e + and the electron antineutrino, e I L e = 0 for all other particles Conservation of Muon Number I Assigning muon number: I L = 1 for the - and the muon neutrino, I L =- 1 for the + and the muon antineutrino I L = 0 for all other particles I Tau numbers are assigned similarly I Lepton number is the sum of electron, muon, and tau numbers Strange Particles I Discovered in the 1950s I Produced in strong interaction I Decayed by weak interaction (long-lived) I Called " strange particles " Conservation of Strangeness I New quantum number, S I Strange particles have integral strangeness ( 1 , 2 , 3) I An antiparticle has strangeness opposite that of the particle I Strangeness is conserved in strong and electromagnetic interactions (when strange particles are produced) I Strangeness can change by one unit in weak interactions (when strange particles decay) Bubble Chamber Example I The dashed lines represent neutral particles I At the bottom, + + p ( S =- 1 ) + K ( S = + 1 ) I Then - ( S = ) + p ( S = ) K - + - ( S = ) + ( S = ) The Standard Model The Eightfold Way Murray Gell-Mann I b. 1929 I Worked on theoretical studies of subatomic particles I Nobel Prize in 1969 The Eightfold Way I The eightfold wayis a symmetric pattern proposed by Gell-Mann and Neeman I These schemes are based on spin, baryon number, strangeness, etc. An Eightfold Way for Baryons I Eight spin 1/2 baryons I Strangeness vs. charge is plotted on a sloping coordinate system I Two particles are at the center I There is a similar pattern for antibaryons An Eightfold Way for Mesons I Nine spins 0 mesons I Plot strangeness vs. charge I The particles and their antiparticles are on opposite sides of the hexagon I The remaining three mesons at the center are their own antiparticles Quarks The Eightfold Way and Quarks I This pattern can be understood in terms of quarks I Three types make up most matter I u- up I d- down I s- strange Quark Model...
View Full Document

This document was uploaded on 12/15/2011.

Page1 / 78

Class27HO - Class 27 The Standard Model and General...

This preview shows document pages 1 - 20. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online