Particles and Interactions. Marina Cobal Corso Fisica Computazionale 2007/2008. Introduction. What is the world made of?. In the ancient time: 4 elements 19 ° century– atoms Beginning 20 th century – electrons, protons, neutrons Today – quarks and leptons.
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…small, smaller…extremely small!…
> 30 soccer fields
< 1 hair
A small stone
And many others…
My PhD thesis!!
Supervisors: H. Grassmann, G. Bellettini
Study of elementary constituents of matter
How pointlike is pointlike?
Wavelenght of probe radiation should be smaller than the object to be resolved
In optical microscope, resolution: Dr ~ l/sinq
With q = angular aperture of the light beam
But l = h/p (De Broglie)
Dr ~ h/p.sinq~ h/q (q = transferred momentum)
Object Size Radiation E
Atom 10-10 m 0.00001 GeV (e)
Nucleus 10-14 m 0.01 GeV (a)
Nucleon 10-15 m 0.1 GeV (e)
Quarks 10-18 m > 1 GeV (e)
Interactions happen by exchange of one or more particles
(carriers or bosons)
R > 106 m (gravitational force)
R ~ 10-10 m (forza elettromagnetica)
R ~ 10-15 m (forza forte)
- “Introduction to Elementary Particles”, D. Griffiths