Quantum Dilaton Gravity in Two Dimensions with Fermionic Matter

Path integral quantization of generic two-dimensional dilaton gravity non-minimally coupled to a Dirac fermion is performed. After integrating out geometry exactly, perturbation theory is employed in the matter sector to derive the lowest order gravitational vertices. Consistency with the case of scalar matter is found and issues of relevance for bosonisation are pointed out.Comment: 27 pages, 3 figures, v2: final version, added references, sec. 2 partially rewritten, some amendments, to be published in Class. Quant. Gra

Ramifications of Lineland

A non-technical overview on gravity in two dimensions is provided. Applications discussed in this work comprise 2D type 0A/0B string theory, Black Hole evaporation/thermodynamics, toy models for quantum gravity, for numerical General Relativity in the context of critical collapse and for solid state analogues of Black Holes. Mathematical relations to integrable models, non-linear gauge theories, Poisson-sigma models, KdV surfaces and non-commutative geometry are presented.Comment: 45 pages, 3 eps figures, proceedings contribution to 5th Workshop on Quantization, Dualities & Integrable Systems in Denizli, Turkey; v2: added refs. and a comment on phase transitions: v3: minor cosmetic chang

Chiral magnetic effect without chirality source in asymmetric Weyl semimetals

We describe a new type of the Chiral Magnetic Effect (CME) that should occur in Weyl semimetals with an asymmetry in the dispersion relations of the left- and right-handed chiral Weyl fermions. In such materials, time-dependent pumping of electrons from a non-chiral external source generates a non-vanishing chiral chemical potential. This is due to the different capacities of the left- and right-handed (LH and RH) chiral Weyl cones arising from the difference in the density of states in the LH and RH cones. The chiral chemical potential then generates, via the chiral anomaly, a current along the direction of an applied magnetic field even in the absence of an external electric field. The source of chirality imbalance in this new setup is thus due to the band structure of the system and the presence of (non-chiral) electron source, and not due to the parallel electric and magnetic fields. We illustrate the effect by an argument based on the effective field theory, and by the chiral kinetic theory calculation for a rotationally invariant Weyl semimetal with different Fermi velocities in the left and right chiral Weyl cones; we also consider the case of a Weyl semimetal with Weyl nodes at different energies. We argue that this effect is generically present in Weyl semimetals with different dispersion relations for LH and RH chiral Weyl cones, such as SrSi2 recently predicted as a Weyl semimetal with broken inversion and mirror symmetries, as long as the chiral relaxation time is much longer than the transport scattering time.Comment: 13 pages, 7 figures; The final publication is available at Springer via http://dx.doi.org/10.1140/epjb/e2018-80418-

Strange Metallic Behaviour and the Thermodynamics of Charged Dilatonic Black Holes

We review a recent holographic analysis arXiv:1005.4690 of charged black holes with scalar hair in view of their applications to the cuprate high temperature superconductors. We show in particular that these black holes show an interesting phase structure including critical behaviour at zero temperature or charge, describe both conductors and insulators (including holographic Mott-like insulators), generically have no residual entropy and exhibit experimentally observed scaling relations between electronic entropy, specific heat and (linear) DC resistivity. Transport properties are discussed in the companion contribution to these proceedings.Comment: 6 pages, 6 figures, to appear in "Proceedings of the XVIth European Workshop on String Theory", Madrid, June 2010, to be published in Fortsch. Phy