Unification, KK-thresholds and the top Yukawa coupling in F-theory GUTs G.K. Leontaris, N.D. Tracas and G. Tsamis Eur. Phys. J. C, 71 10 (2011) 1768 Published online: 01 October 2011 DOI: 10.1140/epjc/s10052-011-1768-1