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. 
Yugo Abe, Yuhei Goto, Yoshiharu Kawamura, and Yasunari Nishikawa
hep-ph astro-ph.CO hep-th