Abundance of real lines on real projective hypersurfaces
  We show that a generic real projective n-dimensional hypersurface of degree 2n-1 contains "many" real lines, namely, not less than (2n-1)!!, which is approximately the square root of the number of complex lines. This estimate is based on the interpretation of a suitable signed count of the lines as the Euler number of an appropriate bundle. 
S.Finashin, V.Kharlamov
math.AG math.GT