112 research outputs found
Intersecting Flavor Branes
We consider an instance of the AdS/CFT duality where the bulk theory contains
an open string tachyon, and study the instability from the viewpoint of the
boundary field theory. We focus on the specific example of the AdS_5 X S^5
background with two probe D7 branes intersecting at general angles. For generic
angles supersymmetry is completely broken and there is an open string tachyon
between the branes. The field theory action for this system is obtained by
coupling to N =4 super Yang-Mills two N =2 hyper multiplets in the fundamental
representation of the SU(N) gauge group, but with different choices of
embedding of the two N=2 subalgebras into N=4. On the field theory side we find
a one-loop Coleman-Weinberg instability in the effective potential for the
fundamental scalars. We identify a mesonic operator as the dual of the open
string tachyon. By AdS/CFT, we predict the tachyon mass for small 't Hooft
coupling (large bulk curvature) and confirm that it violates the AdS stability
bound.Comment: 36 page
Flavor from M5-branes
We study various aspects of the defect conformal field theory that arises
when placing a single M5-brane probe in AdS_4 x S^7. We derive the full set of
fluctuation modes and dimensions of the corresponding dual operators. We argue
that the latter does not depend on the presence of a non-trivial magnetic flux
on the M5-brane world-volume. Finally we give a mass to the hypermultiplet
living on the defect, and compute the resulting mesonic spectrum.Comment: 19 page
Low-Energy Theorems from Holography
In the context of gauge/gravity duality, we verify two types of gauge theory
low-energy theorems, the dilation Ward identities and the decoupling of heavy
flavor. First, we provide an analytic proof of non-trivial dilation Ward
identities for a theory holographically dual to a background with gluon
condensate (the self-dual Liu--Tseytlin background). In this way an important
class of low-energy theorems for correlators of different operators with the
trace of the energy-momentum tensor is established, which so far has been
studied in field theory only. Another low-energy relationship, the so-called
decoupling theorem, is numerically shown to hold universally in three
holographic models involving both the quark and the gluon condensate. We show
this by comparing the ratio of the quark and gluon condensates in three
different examples of gravity backgrounds with non-trivial dilaton flow. As a
by-product of our study, we also obtain gauge field condensate contributions to
meson transport coefficients.Comment: 32 pages, 4 figures, two references added, typos remove
Thermodynamics of Holographic Defects
Using the AdS/CFT correspondence, we study the thermodynamic properties and
the phase diagram of matter fields on (2+1)-dimensional defects coupled to a
(3+1)-dimensional N=4 SYM "heat bath". Considering a background magnetic field,
(net) quark density, defect "magnitude" and the mass of the
matter, we study the defect contribution to the thermodynamic potentials and
their first and second derivatives to map the phases and study their physical
properties.
We find some features that are qualitatively similar to other systems e.g. in
(3+1) dimensions and a number of features that are particular to the defect
nature, such as its magnetic properties, unexpected properties at T->0 and
finite density; and the finite effects, e.g. a diverging
susceptibility and vanishing density of states at small temperatures, a
physically consistent negative heat capacity and new types of consistent
phases.Comment: 33 pages, 16 figures (jpg and pdf), typos fixed and references added,
final version published in JHE
Probe Branes, Time-dependent Couplings and Thermalization in AdS/CFT
We present holographic descriptions of thermalization in conformal field
theories using probe D-branes in AdS X S space-times. We find that the induced
metrics on Dp-brane worldvolumes which are rotating in an internal sphere
direction have horizons with characteristic Hawking temperatures even if there
is no black hole in the bulk AdS. The AdS/CFT correspondence applied to such
systems indeed reveals thermal properties such as Brownian motions and AC
conductivities in the dual conformal field theories. We also use this framework
to holographically analyze time-dependent systems undergoing a quantum quench,
where parameters in quantum field theories, such as a mass or a coupling
constant, are suddenly changed. We confirm that this leads to thermal behavior
by demonstrating the formation of apparent horizons in the induced metric after
a certain time.Comment: LaTeX, 47 pages, 14 figures; Typos corrected and references added
(v2); minor corrections, references added(v3
Rigidity of SU(2,2|2)-symmetric solutions in Type IIB
We investigate the existence of half-BPS solutions in Type IIB supergravity
which are invariant under the superalgebra SU(2,2|2) realized on either AdS_5 x
S^2 x S^1 or AdS_5 x S^3 warped over a Riemann surface \Sigma with boundary. We
prove that, in both cases, the only solution is AdS_5 x S^5 itself. We argue
that this result provides evidence for the non-existence of fully back-reacted
intersecting D3/D7 branes with either AdS_5 x S^2 x S^1 x \Sigma or AdS_5 x S^3
x \Sigma near-horizon limits.Comment: 55 page
Instanton operators in five-dimensional gauge theories
This article is distributed under the terms of the Creative Commons
Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in
any medium, provided the original author(s) and source are creditedN.L. is supported in part by STFC grant ST/J002798/1. C.P. is a Royal Society Research Fellow.N.L. is supported in part by STFC grant ST/J002798/1. C.P. is a Royal Society Research Fellow.N.L. is supported in part by STFC grant ST/J002798/1. OPen Aceess funded by SCOAP
On Non-linear Action for Gauged M2-brane
We propose a non-linear extension of U(1) \times U(1) (abelian) ABJM model
including T_{M2} (higher derivative) corrections. The action proposed here is
expected to describe a single M2-brane proving C^4/Z_k target space. The model
includes couplings with the 3-form background in the eleven-dimensional
supergravity which is consistent with the orbifold projection. We show that the
novel higgs mechanism proposed by Mukhi and Papageorgakis does work even in the
presence of higher derivative corrections and couplings with the background
field, giving the correct structure of the Dirac-Born-Infeld action with
Wess-Zumino term for a D2-brane. We also find half BPS solutions in the full
non-linear theory which is interpreted as an another M2-brane intersecting with
the original M2-brane. A possible generalization to U(N) \times U(N) gauge
group is briefly discussed.Comment: 19 pages, no figure, references added, typos correcte
Chiral primary one-point functions in the D3-D7 defect conformal field theory
JHEP is an open-access journal funded by SCOAP3 and licensed under CC BY 4.0archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2012-81 slaccitation: %%CITATION = ARXIV:1210.7015;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2012-81 slaccitation: %%CITATION = ARXIV:1210.7015;%%C.F.K. and D.Y. were supported in part by FNU through grant number 272-08-0329.
G.W.S. is supported by NSERC of Canada and by the Villum foundation through their
Velux Visiting Professor program
Gauge invariant perturbation theory and non-critical string models of Yang-Mills theories
We carry out a gauge invariant analysis of certain perturbations of
-branes solutions of low energy string theories. We get generically a
system of second order coupled differential equations, and show that only in
very particular cases it is possible to reduce it to just one differential
equation. Later, we apply it to a multi-parameter, generically singular family
of constant dilaton solutions of non-critical string theories in
dimensions, a generalization of that recently found in arXiv:0709.0471[hep-th].
According to arguments coming from the holographic gauge theory-gravity
correspondence, and at least in some region of the parameters space, we obtain
glue-ball spectra of Yang-Mills theories in diverse dimensions, putting special
emphasis in the scalar metric perturbations not considered previously in the
literature in the non critical setup. We compare our numerical results to those
studied previously and to lattice results, finding qualitative and in some
cases, tuning properly the parameters, quantitative agreement. These results
seem to show some kind of universality of the models, as well as an irrelevance
of the singular character of the solutions. We also develop the analysis for
the T-dual, non trivial dilaton family of solutions, showing perfect agreement
between them.Comment: A new reference added
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