Conjugate boundary condition, hidden particles, and gauge-Higgs
  inflation
  We propose an idea that hidden particles can be separated according to gauge
quantum numbers from the visible ones by the difference of boundary conditions
on extra dimensions. We formulate 5-dimensional gauge theories yielding
conjugate boundary conditions besides ordinary ones on $S^1/Z_2$, and examine
physical implications concerning hidden particles on an extension of the
standard model coexisting different types of boundary conditions. A model with
conjugate boundary conditions is applied on a gauge-Higgs inflation scenario.
