Compared to electric or magnetic field lines, which are spread out because the carrier of the electromagnetic force, the photon, does not interact with itself.
It derived from the 1977 PhD thesis of Carsten Peterson, supervised by Bo Andersson and Gösta Gustafson.
[1] The model was refined by the contributions by researchers of the group like Torbjörn Sjöstrand, Bo Söderberg, Gunnar Ingelman, Hans-Uno Bengtsson and Ulf Pettersson.
[1] In 1979, the model was able to describe gluon jet fragmentation by considered the force field to be similar to a massless relativistic string.
[1] The model successfully predicted a specific asymmetry in the particles produced in electron–positron collisions, observed in 1980.