Asymptotic Freedom of the
Strong Interaction
Matthew Musgrave
At very short distances or very high energies the forces experienced by
strongly interacting particles approaches zero. This phenomenon is
known as asymptotic freedom. For his work Dr. Politzer received the
Nobel Prize in physics in 2004.
In QED the force experience by electrically
charged particles approaches infinity as the
distance between the particles approaches
zero due to the inverse r2 relationship of the
Coulomb force.
The force experience by particles in QCD is
described by the Yang-Mills theory, which
has the property of asymptotic freedom. As
the distance between two quarks
asymptotically approaches zero, the force
becomes arbitrarily weak and the quarks
appear to be free. Similarly quarks at very
high energies appear to exist as free
particles, such as in the quark-gluon plasma.
The beta-function describes how the coupling constant of
the strong force g changes under a renormalization group.
Since the beta-function is negative, the coupling constant g
and therefore the force experienced by quarks or gluons
becomes arbitrarily small at shorter distances and higher
energies.