Fluctuation of Valley Density Wave in Iron Pnictides

We studied the fluctuations within the U(n)*U(n) [1] theory, which was developed to explain the magnetic and structural transitions in the parent compound of iron pnictides. The self-energy of the fermion contains singularity in low energy scale. It behaves similar to marginal Fermi liquid theory and depends on n. The optical conductivity and spin lattice relaxation time are calculated and compared with some experiment on ``pseudogap'' in iron pnictides. More experiments are proposed to provide a direct view our U(4)*U(4) theory being assembled as one moves from low to high energies. \\[4pt] [1] J. Kang and Z. Tesanovic, Phys. Rev. B 83, 020505(R) (2011).