Can Theta/N Dependence for Gluodynamics be Compatible with 2 pi Periodicity in Theta ?

In a number of field theoretical models the vacuum angle \theta enters physics in the combination \theta/N, where N stands generically for the number of colors or flavors, in an apparent contradiction with the expected 2 \pi periodicity in \theta. We argue that a resolution of this puzzle is related to the existence of a number of different \theta dependent sectors in a finite volume formulation, which can not be seen in the naive thermodynamic limit V -> \infty. It is shown that, when the limit V -> \infty is properly defined, physics is always 2 \pi periodic in \theta for any integer, and even rational, values of N, with vacuum doubling at certain values of \theta. We demonstrate this phenomenon in both the multi-flavor Schwinger model with the bosonization technique, and four-dimensional gluodynamics with the effective Lagrangian method. The proposed mechanism works for an arbitrary gauge group.Comment: minor changes in the discussion, a few references are adde

Tenacious Domain Walls in Supersymmetric QCD

We study the structure of the tenacious (existing for all values of masses of the matter fields) BPS domain walls interpolating between different chirally asymmetric vacua in supersymmetric QCD in the limit of large masses. We show that the wall consists in this case of three layers: two outer layers form a ``coat'' with the characteristic size determined by \Lambda_{SYM} and there is also the core with width of order of inverse mass. The core always carries a significant fraction of the total wall energy. This fraction depends on $N_f$ and on the ``windings'' of the matter fields.Comment: 14 pages, 5 figures. Some extra discussion and references adde

Governing Boards and Profound Organizational Change in Hospitals

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69047/2/10.1177_107755878904600204.pd