Do whatever is most prevalent in your target journal.
This is a convention of academic publishing.
For a while, two of the major competing medical journals, The Lancet and the BMJ, had different policies on title colons: one journal had colons in most of its titles; the other had colons in very few. If you submitted an article with a title containing a colon, to the wrong journal, it would seriously dent your chance of the article getting submitted.
As with all aspects of language, context is crucial.
In this case, the context is other titles in your target journal. So be consistent with them. Go through the 100 most recently-accepted published papers, and count how many have a colon in the title. If it's over 55, use a colon, if it's under 45, don't. And if it's between, do as you wish.