247 research outputs found
Holographic duality with a view toward many-body physics
These are notes based on a series of lectures given at the KITP workshop
"Quantum Criticality and the AdS/CFT Correspondence" in July, 2009. The goal of
the lectures was to introduce condensed matter physicists to the AdS/CFT
correspondence. Discussion of string theory and of supersymmetry is avoided to
the extent possible.Comment: 64 pages, many figures; v2: references, clarifications; v3: minor
correction
An analytic Lifshitz black hole
A Lifshitz point is described by a quantum field theory with anisotropic
scale invariance (but not Galilean invariance). In arXiv:0808.1725, gravity
duals were conjectured for such theories. We construct analytically a black
hole which asymptotes to a vacuum Lifshitz solution; this black hole solves the
equations of motion of some simple (but somewhat strange) extensions of the
models of arXiv:0808.1725. We study its thermodynamics and scalar response
functions. The scalar wave equation turns out to be exactly solvable.
Interestingly, the Green's functions do not exhibit the ultralocal behavior
seen previously in the free Lifshitz scalar theory.Comment: 18 page
Remarks on branes, fluxes, and soft SUSY breaking
We review recent work identifying soft SUSY-breaking terms in local type II
string models with branes and magnetic fluxes. We then make a new observation
about the configuration space of D-branes in Calabi-Yau backgrounds, and
identify vevs for nonperturbative charged hypermultiplets in Calabi-Yau
backgrounds with N=2 Fayet-Iliopoulos terms.Comment: 11 pages, 2 figures, uses ws-procs9x6.cls, contribution to conference
proceedings for QTS
Continuous transitions between composite Fermi liquid and Landau Fermi liquid: a route to fractionalized Mott insulators
One of the most successful theories of a non-Fermi liquid metallic state is
the composite Fermi liquid (CFL) theory of the half-filled Landau level. In
this paper, we study continuous quantum phase transitions out of the CFL state
and into a Landau Fermi liquid, in the limit of no disorder and fixed particle
number. This transition can be induced by tuning the bandwidth of the Landau
level relative to the interaction energy, for instance through an externally
applied periodic potential. We find a transition to the Landau Fermi liquid
through a gapless Mott insulator with a Fermi surface of neutral fermionic
excitations. In the presence of spatial symmetries, we also find a direct
continuous transition between the CFL and the Landau Fermi liquid. The
transitions have a number of characteristic observable signatures, including
the presence of two crossover temperature scales, resistivity jumps, and
vanishing compressibility. When the composite fermions are paired instead, our
results imply quantum critical points between various non-Abelian topological
states, including the \nu = 1/2 Moore-Read Pfaffian (Ising x U(1) topological
order), a version of the Kitaev B phase (Ising topological order), and paired
electronic superconductors. To study such transitions, we use a projective
construction of the CFL, which goes beyond the conventional framework of flux
attachment to include a broader set of quantum fluctuations. These
considerations suggest a possible route to fractionalized Mott insulators by
starting with FQH states and tuning the Landau level bandwidth.Comment: 15 page
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