Spark image

Quarks

All hadrons (mesons and baryons) are composed of particles called QUARKS.

Quarks have fractional electric charge compared with the charge on the electron of -e.
Their existence was confirmed by high energy electron scattering from the nucleons.
We will only consider two types of quark here:


Up quark with a charge +2/3 e
Down quark with a charge - 1/3 e

Baryons such as protons and neutrons are made of three quarks. The quarks are held together to form a larger particle by the strong force produced by the exchange of gluons between them.



Proton   up up down uud   charge = +2/3 +2/3 -1/3 = +1
Neutron   down down up ddu   charge = -1/3 -1/3 +2/3 = 0


Mesons are composed of one quark and one anti-quark. For example a p+ meson is composed of one up quark and one anti-down quark.


Electrons and neutrinos contain no quarks, they are truly fundamental particles themselves.

When you try and drag a quark out of a particle the strong force field between the quarks gets bigger and bigger rather like the force in a rubber band as it is stretched.

 
 
 
© Keith Gibbs 2011