  Let $Z$ be a Fano variety satisfying the condition that the rank of the
Grothendieck group of $Z$ is one more than the dimension of $Z$. Let $\omega_Z$
denote the total space of the canonical line bundle of $Z$, considered as a
non-compact Calabi-Yau variety. We use the theory of exceptional collections to
describe t-structures on the derived category of coherent sheaves on
$\omega_Z$. The combinatorics of these t-structures is determined by a natural
action of an affine braid group, closely related to the well-known action of
the Artin braid group on the set of exceptional collections on $Z$.
