The emergence of strange metal and topological liquid near quantum critical point in a solvable model

We discuss quantum phase transition by a solvable model in the dual gravity setup. By considering the effect of the scalar condensation on the fermion spectrum near the quantum critical point(QCP), we find that there is a topologically protected fermion zero mode associated with the metal to insulator transition. Unlike the topological insulator, our zero mode is for the bulk of the material, not the edge. We also show that the strange metal phase with T-linear resistivity emerges at high enough temperature as far as a horizon exists. The phase boundaries calculated according to the density of states allow us understanding the structures of the phase diagram near the QCP.

NEUTRINO PHYSICS WITH SMALL EXTRA DIMENSIONS

We study neutrino physics in the context of the localized gravity model with non-factorizable metric proposed by Randall and Sundrum. Identifying the right-handed neutrino with a bulk fermion zero mode, which can be localized on the "hidden" 3-brane in the Randall-Sundrum model, we obtain naturally small Dirac neutrino masses with-out invoking a see-saw mechanism. Our model predicts a strong hierarchy of neutrino masses and generically large mixing angles.