Gauge Theories on de Sitter Spacetime
  In this paper we will analyse the inner product for gauge theories in de Sitter spacetime. This will be done by analysing an Euclidean version of the de Sitter metric. Thus, the de Sitter metric will be related to the metric on a four-sphere. Then scalar spherical harmonics and vector spherical harmonics on a four-sphere will be analysed. An inner product for the gauge fields will be constructed using these modes. Finally, a two point function will be constructed, for gauge fields on de Sitter spacetime. 
Asloob Ahmad Rather, Ashaq Hussain Sofi, Shabir Ahmad Akhoon, Anil   Maini
physics.gen-ph