Excursions through KK modes
  In this article we study Kaluza-Klein (KK) dimensional reduction of massive
Abelian gauge theories with charged matter fields on a circle. Since local
gauge transformations change position dependence of the charged fields, the
decomposition of the charged matter fields into KK modes is gauge dependent.
While whole KK mass spectrum is independent of the gauge choice, the mode
number depends on the gauge. The masses of the KK modes also depend on the
field value of the zero-mode of the extra dimensional component of the gauge
field. In particular, one of the KK modes in the KK tower of each massless 5D
charged field becomes massless at particular values of the extra-dimensional
component of the gauge field. When the extra-dimensional component of the gauge
field is identified with the inflaton, this structure leads to recursive
cosmological particle productions.
