PX434 – Physics of the Standard ModelDr Steven Boyd : P448

ATLAS Event Display

Intro Stuff

Lectures are divided in chapters – each chapter has a writeup which will be put onlineThere is a module homepage

http://www.warwick.ac.uk/fac/sci/physics/teach/module_home/px434/

Books:D. Griffiths,Introduction to Elementary Particles,

Prentice-HallD. Perkins, Introduction to High Energy PhysicsR. Feynman, Lectures on Physics Vol II F. Halzen and A.D.Martin, Quarks and Leptons

Griffiths is the main text, supplemented by Perkins. Halzen andMartin is quite technical, and somewhat out of date for material from the last 10-15 years

Recommended Text

Course Overview History of Particle Physics : Beginning Lecture Chapter 1 : Introduction and Preliminaries : Standard Model, Feynman Diagrams,

Conservations Laws and Symmetries, Units and Relativistic Kinematics, Decay rates and Cross sections, Group Theory Chapter 2 : Quantum Electrodynamics : Bosons and Fermions, The Klein-Gordon

and Dirac Equations, Spinors, Feynman diagrams, Electron-Muon Scattering Chapter 3 : The Strong Interaction : Isospin, Strangeness, The eight-fold way,

Quark theory and evidence for quarks, evidence for colour, QCD, Confinement and asymptotic freedom Chapter 4 : The Weak Interaction : Weak and Neutral currents, Parity violation and

the V-A current, Cabibbo theory and the GIM mechanism, Kaon oscillations, CP violation Chapter 5 : Pulling it all together – the Standard Model : The Weak coupling,

Electroweak unification, Weinberg angle, Z0 decay Chapter 6 : Spontaneous Symmetry breaking and the Higgs : Mass in the

Standard Model, Spontaneous Symmetry Breaking, The Higgs potential, Higgs mass and the LHC Chapter 7 : Beyond the Standard Model : Problem with the Standard Model,

Grand Unification, Unanswered Questions, Where to go from here

Including an examples class after every chapter

A brief history of particle physics

Concept of the atom developed by Democritusand several ancient schools of early Hindu philosophyin India.

6-5 Century BC

1709-1899

Discovery of electrons – ending with JJ Thompson andthe plum pudding model of the atom

1917-1919

Discovery of protons by Rutherford with his famousgold foil experiment

A Brief History of Particle Physics

1930's

Neutron (after 1932)Neutrino (proposed, but not seen until 1956)Photon

1932

Positron, predicted by Dirac, discovered byAnderson

Neutron discovered by Chadwick

Pions and Muons

Yukawa suggested that the nuclear force was due to the exchange of particles (mesons)

Muon discovered, prompting Rabi to say“Who ordered that” at a major conference

Charged pion discovered, and found to decay to muons

Neutral pion discovered

1935

1937

1946

QED1950

Feynman, Schwinger and Tomonaga synthesised a coherent theory of electron-photon interactions from early quantum mechanics. This is called Quantum Electrodynamics

Strangeness

1946 : particle physics understood. Nothing really new to discover

1947 : Kaon discovered, followed by the Lambda. Thesenew particles were tagged as “strange” particles

Produced in strong interactionbut decay via weak interaction

Always produced in pairs : Gell-Mann and Nishijima propose a new conservedquantum number : Strangeness

The Particle Zoo

1950's – 1970's : Bewildering array of new particlesdiscovered. Physicists begin to despair about understandingflood of new particles.

The Eight-Fold Way1961 : Murray Gell-Mann fits all the known particles intosimple frameworks. Later it turns out that these structuresare predicted from group theory and the proposition of quarks

Quarks1964 : Why is the eight-fold way successful? Gell-Mann and Zweig propose that all known particles made up ofquarks and anti-quarks which he imagines as localisedquantum numbers, but not localised particles

Noone believes them to be anything other than anaccounting trick until 1974.

1964 : Brout, Englert, Guralnik, Hagen, Kibble and Higgspropose a mechanism by which particles attain mass.This is tested, off and on, for the next 45 years.

1974 : Discovery of the charm quark in the J/Ψ – thisvalidates the quark model and cements quarks as “real”particles.

QCD1970's : a theory of the strong interaction is devised by Gell-Mann and Feynman calledQuantum Chromodynamics involving a newquantum number called colour.

1970's : improved understanding of the weak interactionallows Salam, Glashow and Weinberg to unify it withthe EM interaction to create the “Electroweak” Interaction

More particles

1973 : Neutral Current interactions are discovered

1975 : the tau lepton is detected at SLAC

1978 : the bottom quark is detected at Fermilab

1979 : the gluon – the colour force carrier is discovered at DESY

More particles

1983 : the W±/Z0 - the electroweak force carriers are measured at CERN by UA1 and UA2

1995 : the top quark is (finally) discovered at Fermilabwith a mass of 172 GeV.

Up-to-date

1998 – Now : Neutrinos are shown to be massive throughneutrino flavour oscillations (see PX435)

Two months ago : a Higgs-type thing is discovered.

What next?

GoalThe goal of this course is to discuss thephysics behind the Standard Model.We will not, explicitly, write the entire Model down as, although doing so can give us some insights, it requires a bit of background.

If you want to see the model, take the Gauge Theories and the Neutrinos course next term.

We will look at the physics of each of main forces in turn, and try to outline experimental evidence for their current formulation

Quantum ElectrodynamicsThe Strong Force and Quantum ChromodynamicsThe Weak forceSpontaneous Symmetry breaking and the Higgs Field.

The Standard Model

GoalThe goal of this course is to discuss thephysics behind the Standard Model.We will not, explicitly, write the entire Model down as, although doing so can give us some insights, it requires a bit of background.

If you want to see the model, take the Gauge Theories and the Neutrinos course next term.

We will look at the physics of each of main forces in turn, and try to outline experimental evidence for their current formulation

Quantum ElectrodynamicsThe Strong Force and Quantum ChromodynamicsThe Weak forceSpontaneous Symmetry breaking and the Higgs Field.