Note: This is my second answer on this question. It uses much of the same information as my first answer but comes to a different conclusion. I wanted to make sure that votes for my other answer did not erroneously count against this answer. Both answers feel accurate to me, based on slightly different points of view.
##It's not called out, but there's precedent: go for it##
It's not called out, but there's precedent: go for it
###Relevant Excerpts###
Relevant Excerpts
Spellcasting Focus
You can use an arcane focus (found in chapter 5) as a spellcasting focus for your wizard spells.
D&D Basic Rules V0.2, page 30
Arcane Focus. An arcane focus is a special item—an orb, a crystal, a rod, a specially constructed staff, a wand-like length of wood, or some similar item—designed to channel the power of arcane spells. A sorcerer, warlock, or wizard can use such an item as a spellcasting focus, as described in chapter 10.
D&D Basic Rules V0.2, page 47
Analysis
###Analysis### TheThe Adventuring Gear table on page 48 lists 5 possibilities for an Arcane Focus (which mirrors the list on page 47): Crystal, Orb, Rod, Staff, Wand. None of these are bows. None of these even appear to be weapons: initially, I'd rule, "No, it's not possible per RAW."
However, while researching Can the arcane/druidic focus staff double as quarterstaff?, I asked Mike Mearls: "Can the arcane/druidic focus staff double as a quarterstaff?" And received the following response: "yes"
This means that there is precedent for allowing an Arcane Focus as a weapon. Notice, however, that the Arcane Focus Staff is 25 times more expensive than a plain Quarterstaff: make sure your Arcane Focus Bow is significantly more expensive than a regular bow.