I have something like
\[a = \langle a + b, c + d, e + f \rangle\]
But I want to stack another vector right above the right hand side, centered horizontally (with respect to corresponding elements of a), but without angle brackets, namely
x y z a = < a + b, c + d, e + f >
\overset but it's not satisfactory because the upper vector will be smaller. I also tried
\genfrac but it pushes the original vector down. (I don't want the angle brackets to extend to cover two lines.) How can I achieve this?