WHATS IN AN ATOM MATTER Atom 10 10

WHAT’S IN AN ATOM?

MATTER Atom ~10 -10 m Nucleus ~10 -15 m Quarks <10 -18 m

MATTER Atom ~10 -10 m Nucleus ~10 -15 m Fundamental Particles: ØElectron ØQuarks: Up (u) & Down (d) Force Carriers: ØPhoton: carries EM force ØGluon: binds quarks in nuclei Quarks <10 -18 m

3 Generations of Matter: ØHeavier ØSame properties and interactions.

3 Generations of Matter: ØHeavier ØSame properties and interactions. ØFelt only by Quarks ØForce increases with distance – binds quarks into proton/neutrons

3 Generations of Matter: ØHeavier ØSame properties and interactions. ØAffects only Quarks ØAffects all particles ØForce increases with distance – binds quarks into proton/neutrons ØResponsible for nuclear/radioactive decay ØMassive bosons?

3 Generations of Matter: ØHeavier ØSame properties and interactions. ØFelt only by Quarks ØAffects all particles ØAffects all charged particles ØForce increases with distance – binds quarks into proton/neutrons ØResponsible for nuclear/radioactive decay ØCauses lightning, magnetic fields

3 Generations of Matter: ØHeavier ØSame properties and interactions. ØFelt only by Quarks ØAffects all particles ØAffects all charged ØTiny effects on individual particles ØForce increases with distance – binds quarks into proton/neutrons ØResponsible for nuclear/radioactive decay ØCauses lightning, magnetic fields ØMassive bosons? ØExplains Chemistry? ? ? ØNot included in the Standard Model

THE HIGGS BOSON One particle predicted by the Standard Model has yet to be discovered: The HIGGS particle

THE HIGGS BOSON One particle predicted by the Standard Model has yet to be discovered: The HIGGS particle ØNeeded to explain how the other particles gain masses ØLEP at CERN excluded masses below 114 Ge. V ØMust have a mass less than 1000 Ge. V for the model to be correct ØMajor motivation for building the LHC at CERN

THE HIGGS BOSON One particle predicted by the Standard Model has yet to be discovered: The HIGGS particle ØNeeded to explain how the other particles gain masses ØLEP at CERN excluded masses below 114 Ge. V ØMust have a mass less than 1000 Ge. V for the model to be correct ØMajor motivation for building the LHC at CERN WILL DISCOVER THE HIGGS PARTICLE OR, IF THE MODEL IS WRONG, SOMETHING ELSE !

UNANSWERED QUESTIONS ØWhy 3 generations? ØWhy 4 forces – can they be unified? ØMany parameters, masses, etc. must be put in by hand ØDifficult to keep the Higgs mass small ØDark Matter – what is it? ØGravity – how do we include it?

UNANSWERED QUESTIONS ØWhy 3 generations? ØWhy 4 forces – can they be unified? ØMany parameters, masses, etc. must be put in by hand ØDifficult to keep the Higgs mass small ØDark Matter – what is it? ØGravity – how do we include it? Theorists have hypothesised many models to explain these, eg. ØSupersymmetry – predicts a heavier partner for each particle in the SM ØExtra dimensions – possibility of producing minute black holes that decay in the detector after 10 -26 s

Backups

The Standard Model 3 Generations of Particles Lightest Heaviest