170 research outputs found
Isospin diffusion in thermal AdS/CFT with flavor
We study the gauge/gravity dual of a finite temperature field theory at
finite isospin chemical potential by considering a probe of two coincident
D7-branes embedded in the AdS-Schwarzschild black hole background. The isospin
chemical potential is obtained by giving a vev to the time component of the
non-Abelian gauge field on the brane. The fluctuations of the non-Abelian gauge
field on the brane are dual to the SU(2) flavor current in the field theory.
For the embedding corresponding to vanishing quark mass, we calculate all Green
functions corresponding to the components of the flavor current correlator. We
discuss the physical properties of these Green functions, which go beyond
linear response theory. In particular, we show that the isospin chemical
potential leads to a frequency-dependent isospin diffusion coefficient.Comment: 26 pages, 8 figures, typos correcte
From Maxwell-Chern-Simons theory in towards hydrodynamics in 1+1 dimensions
We study Abelian Maxwell-Chern-Simons theory in three-dimensional black
hole backgrounds for both integer and non-integer Chern-Simons coupling. Such
theories can be derived from various string theory constructions, which we
review in the present work. In particular we find exact solutions in the low
frequency, low momentum limit, (hydrodynamic limit). Using the
holographic principle, we translate our results into correlation functions of
vector and scalar operators in the dual strongly coupled 1+1-dimensional
quantum field theory with a chiral anomaly at non-zero temperature .
Starting from the conformal case we show applicability of the hydrodynamic
limit and discuss extensions to the non-conformal case. Correlation functions
in the conformal case are compared to an exact field theoretic computation.Comment: 41 pages + appendix, 4 figures, 1 tabl
Fermionic Operator Mixing in Holographic p-wave Superfluids
We use gauge-gravity duality to compute spectral functions of fermionic
operators in a strongly-coupled defect field theory in p-wave superfluid
states. The field theory is (3+1)-dimensional N=4 supersymmetric SU(Nc)
Yang-Mills theory, in the 't Hooft limit and with large coupling, coupled to
two massless flavors of (2+1)-dimensional N=4 supersymmetric matter. We show
that a sufficiently large chemical potential for a U(1) subgroup of the global
SU(2) isospin symmetry triggers a phase transition to a p-wave superfluid
state, and in that state we compute spectral functions for the fermionic
superpartners of mesons valued in the adjoint of SU(2) isospin. In the spectral
functions we see the breaking of rotational symmetry and the emergence of a
Fermi surface comprised of isolated points as we cool the system through the
superfluid phase transition. The dual gravitational description is two
coincident probe D5-branes in AdS5 x S5 with non-trivial worldvolume SU(2)
gauge fields. We extract spectral functions from solutions of the linearized
equations of motion for the D5-branes' worldvolume fermions, which couple to
one another through the worldvolume gauge field. We develop an efficient method
to compute retarded Green's functions from a system of coupled bulk fermions.
We also perform the holographic renormalization of free bulk fermions in any
asymptotically Euclidean AdS space.Comment: 68 pages, 25 eps files in 9 figures; v2 minor corrections, added two
references, version published in JHE
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