I'm studying Group Theory by myself and I face the basic concept regarding superscript and subscript indices on the Kronecker delta tensor:
What is the meaning (or difference) of these symbols?
I thought I knew what the "Kroneker delta" was but it certainly isn't a tensor! [itex]\delta_{\alpha\beta}[/itex] is the array that is 1 if [itex]\alpha= \beta[/itex] and 0 otherwise. That doesn't depend on any coordinate system and so does not transform as a tensor would under a change of coordinate systems.