The word is
(α-β) shows the two Greek letters alpha and beta, therefore hinting toward the alphabet.
And indeed, the alphabet is represented by each pair of parenthesized letters... but only partially. For example, (AC)(LZ) represents the letters from A to C, then L to Z. To complete the alphabet, we take the skipped letters: D, E, F, G, H, I, J, and K.
Doing this for each pair of parenthesized letters (going back to A if we reach a Z), we get this:
(AC) D E F G H I J K (LZ)
(AG) H I J K L M N O (PZ)
(SX) Y Z A B C D E F (GR)
(QC) D E F G H I J K (LP)
(XJ) K L M N O P Q R (SW)
(BH) I J K L M N O P (QA)
(JT) U V W X Y Z A B (CI)
(SD) E F G H I J K L (MR)
and so we have an 8x8 grid of letters which corresponds with the given blank 8x8 grid.
And finally, notice that the word "diagonal" is written along the main... diagonal! Hence the title is completed with the answer itself: "You'll find it if you go along the diagonal."