Is there a way to do negative lookahead in vim regex?

Question

In Vim, is there a way to search for lines that match say abc but do not also contain xyz later on the line? So the following lines would match:

<

Answer 1

Although your question is about lookahead, I found it while searching for lookbehind. Thus, I post the solution to lookbehind so that others may find it.

If you search for pattern2 not preceded by pattern1, that is negative lookbehind, search for:

\(pattern1\)\@