I am confused about the very step from Eq.(14) to Eq.(15) in the paper(adsbygoogle = window.adsbygoogle || []).push({});

http://arxiv.org/pdf/hep-ph/0308157.pdf

There is one ##ig## in (14), while ##(ig)^2## in (15), where does it come from?

Regards!

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# About the gluon feild and propagator

**Physics Forums | Science Articles, Homework Help, Discussion**