  Starting from the $CP^{N-1}$ model description of the thermally disordred
phase of the $D=2$ quantum antiferromagnet, we examine the interaction of the
Schwinger-boson spin-1/2 mean-field excitations with the generated gauge
(chirality) fluctuations in the framework of the 1/N expansion. This
interaction dramatically supresses the one-particle motion, but enhances the
staggered static susceptibility. This means that actual excitations in the
system are represented by the collective spin-1 excitations, whereas
one-particle excitations disappear from the problem. We also show that massive
fluctuations of the constraint field are significant for the susceptibility
calculations. A connection with the problem of a particle in random magnetic
field is discussed.
