On M-Theory Embedding of Topologically Massive Gravity

We show that topologically massive gravity can be obtained by the consistent Kaluza-Klein reduction from recently constructed seven-dimensional gravity with topological terms. The internal four-manifold should be Einstein with the Pontryagin four-form constantly proportional to the volume form. We also discuss the possible lift of the system to D=11. This enables us to connect the mass parameter \tilde\mu in D=3 to the M5-brane charge. The dimensionless quantity 3/(G\tilde \mu) is discrete and proportional to N, where N is the number of M5-branes.Comment: 8 pages, no figures, references added, version appeared in Int.J.Mod.Phys.

Most General Spherically Symmetric M2-branes and Type IIB Strings

We obtain the most general spherically symmetric M2-branes and type IIB strings, with \R^{1,2}\times SO(8) and \R^{1,1}\times SO(8) isometries respectively. We find that there are twelve different classes of M2-branes, and we study their curvature properties. In particular we obtain new smooth M2-brane wormholes that connect two asymptotic regions: one is flat and the other can be either flat or AdS_4\times S^7. We find that these wormholes are traversable with certain time-like trajectories. We also obtain the most general Ricci-flat solutions in five dimensions with \R^{1,1}\times SO(3) isometries.Comment: 37 pages, 1 table, revised version to appear in PR

Exact Green's Function and Fermi Surfaces from Conformal Gravity

We study the Dirac equation of a charged massless spinor on the general charged AdS black hole of conformal gravity. The equation can be solved exactly in terms of Heun's functions. We obtain the exact Green's function in the phase space (\omega,k). This allows us to obtain Fermi surfaces for both Fermi and non-Fermi liquids. Our analytic results provide a more elegant approach of studying some strongly interacting fermionic systems not only at zero temperature, but also at any finite temperature. At zero temperature, we analyse the motion of the poles in the complex \omega plane and obtain the leading order terms of the dispersion relation, expressed as the Laurent expansion of \omega in terms of k. We illustrate new distinguishing features arising at the finite temperature. The Green's function with vanishing \omega at finite temperature has a fascinating rich structure of spiked maxima in the plane of k and the fermion charge q.Comment: 12 pages, typos corrected, further discussions on the properties of the Green's function and dispersion relation, new figures of the motion of poles added. Version to appear in Phys. Lett.