On Tannaka duality for vector bundles on p-adic curves
  We prove that a category of degree zero vector bundles with "potentially strongly semistable reduction" on a p-adic curve is a neutral Tannakian category. We also make a first study of the corresponding affine group scheme. In particular, we determine its group of connected components using a theorem of Weil. 
C. Deninger, A. Werner