# Why does the energy density of the gluon field have any connection to electric or magnetic field strength?

In the video Revealing The Origin of Mass Professor Derek Leinweber gives the formula for energy density of the gluon field as simply the electric field strength squared plus the magnetic field strength squared, over the range of the 8 gluons. Why is there any connection between gluon energy density and electric or magnetic field strength. Quarks and electrons have electric charge and thus magnetic fields, but gluons only have color charge or chromoelectric charge, which is not the same as normal electric charge. What is the connection to the electric charge that makes Leinweber's formula appropriate?

• *Chromoelectric and Chromomagnetic fields Aug 18, 2022 at 16:30
• @JeanbaptisteRoux According to this answer, chromooelectric fields are very different from normal electric fields: physics.stackexchange.com/questions/426507/… So can you provide me something that ties them to the electric field strength in a way that makes the formulas suitable? Aug 20, 2022 at 17:47
• They are defined the same way: through the curvature of the gauge field. The difference resides in the difference in their gauge group. Have you read the Wikipedia entry on the gluon field? Aug 20, 2022 at 17:59
• You are misunderstanding the video - the "electric" and "magnetic" fields here are supposed to be the chromo-* fields. There is no "connection to electric charge". Aug 20, 2022 at 17:59
• @ACuriousMind is there some way to see that he is referring to chromo fields in the video? Aug 20, 2022 at 18:21