G.G. Barnafoldi: "Searching Extra Dimensions in Compact Stars" Abstract: The electro-magnetic and particle radiation detected from the direction of Cygnus X3 raise the question of the existence of special long-lived, neutral particles. We investigate the origin of these particles in a special approach: the source object may contain compactified extra dimension and these particles are messengers of this state. We describe hyperon stars in 3+1 dimension and introduce the description of a compact stars in 3+1_c+1 dimensional Kaluza-Klein like space-time.