Gustafson]{}\
\[2mm\] [*Department of Theoretical Physics,*]{}\
[*Lund University, Lund, Sweden*]{}

![image](./lejon1.eps)

Introduction
============

> *It remains that, from the same principles, I now demonstrate the frame of the System of the World.\
> Isaac Newton\
> Book III, Philosophiae Naturalis Principia Mathematica, 1687*

Deep Inelastic Scattering (DIS) is a scattering process where the target particle disintegrates and what comes out is very different from what came in. If on the other hand the system after the collision looks exactly like the system before the collision we call the process elastic. A very common process to study is the collision between an electron and a proton. This process is usually deeply inelastic at high energies, which is due to the fact that the proton is not an elementary particle but is instead made up of even smaller particles, the quarks. This was observed in 1968, and it was found that the proton consist of three quarks, two up-quarks and one down-quark. However, the picture is not as simple as that. Since the quarks interact via the strong force which is mediated by the gluons, there are also a lot of gluons in the proton. These gluons can create quark-antiquark pairs or 