# Symmetries in Sidney Colemans QFT script

by silverwhale
Tags: colemans, script, sidney, symmetries
 P: 67 Hello Everybody, I am learning QFT using Sidney Colemans lecture notes (and the Peskin Schroeder book). They can be found here: http://arxiv.org/abs/1110.5013 Now, in page 40, he introduces in the paragraph Symmetries and Conservation laws some definitions which I don't quite understand. First he writes, $$q^a(t) \rightarrow q^a(t,\lambda).$$ For a transformation of the generalized coordinates. Second he defines, $$Dq^a \equiv \frac{\partial q^a}{\partial \lambda}.$$ Now my question is just, does anybody recognize these definitions? is there some book where I can find, learn and play with them? I never saw such a definition for a symmetry. Well, if no literature exsits, can anybody explain to me what this derivative means? Thanks alot!!