By my count, the Journal of Mathematics and Music [subtitled: Mathematical and Computational Approaches to Music Theory, Analysis, Composition, and Performance] from its inception in 2007 contains about five [+/- a few] articles specifically devoted to some theoretical consideration of rhythm and or meter. The to-some [metric theory enthusiasts] well known Toussaint co-authors two of these (2009). In general, the journal contributors seem to hover around popular mathematic watering holes (or water coolers): scale theory, transformation theory, set theory, which places pitch prima inter pares among musical elements. The smallish seeming number is perhaps glibly suggestive: the journal is young, as is the faction it supports; and there are also roughly about three substantial articles per issue thrice annually.
-S P G