Erlewine, Michael Yoshitaka, to appear. “Vietnamese focus particles and derivation by phase.”
Journal of East Asian Linguistics.

I show that the focus-sensitive operator ‘only’ chỉ in Vietnamese is a sentential modifier and required to be as low as possible in its phase while taking its focus associate in its scope. I show that this “as low as possible” requirement cannot be violated even in order to yield a different meaning. Within a phase-based, bottom-up conception of structure-building, I analyze this behavior as the result of sentential focus particles adjoining as early as possible while being interpretable. The fact that this requirement only holds between different adjunction positions in each phase is naturally explained by the theory of derivation by phase (Chomsky, 2000, 2001) and provides a new kind of evidence for this form of cyclic structure-building. This work also provides cross-linguistic support for one aspect of the controversial analysis of German focus particles as sentential modifiers (Jacobs, 1983, 1986; Büring and Hartmann, 2001), which similarly requires an ‘‘as low as possible” requirement on sentential focus particles.

See also “Minimality and focus-sensitive adverb placement” in NELS 45, which discusses various alternative analyses.