Compactification driven hilltop inflation in Einstein-Yang-Mills theory

Starting from Einstein-Yang-Mills theory in higher dimensions with an instanton on a compact sphere, we dimensionally reduce to find an effective four-dimensional action describing "hilltop" inflation. Using recent CMB data, we analyze the parameter space of this model to search for viable setups. One unique feature of this class of inflationary models is that the value of the inflaton field, or alternatively, the size of the compact sphere, is stabilized dynamically during the inflationary process.