Physics Letters B 746 (2015) 318–324
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Physics Letters B
www.elsevier.com/locate/physletb
Lifshitz space–times for Schrödinger holography
Jelle Hartong
a
, Elias Kiritsis
b,c
, Niels A. Obers
a,∗
a
The Niels Bohr Institute, Copenhagen University, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark
b
Crete Center for Theoretical Physics, Department of Physics, University of Crete, 71003 Heraklion, Greece
c
APC, Université Paris 7, CNRS/IN2P3, CEA/IRFU, Obs. de Paris, Sorbonne Paris Cité, Bâtiment Condorcet, F-75205, Paris Cedex 13, (UMR du CNRS 7164), France
a r t i c l e i n f o a b s t r a c t
Article history:
Received
15 March 2015
Received
in revised form 5 May 2015
Accepted
7 May 2015
Available
online 9 May 2015
Editor:
M. Cveti
ˇ
c
We show that asymptotically locally Lifshitz space–times are holographically dual to field theories that
exhibit Schrödinger invariance. This involves a complete identification of the sources, which describe
torsional Newton–Cartan geometry on the boundary and transform under the Schrödinger algebra. We
furthermore identify the dual vevs from which we define and construct the boundary energy–momentum
tensor and mass current and show that these obey Ward identities that are organized by the Schrödinger
algebra. We also point out that even though the energy flux has scaling dimension larger than z + 2, it
can be expressed in terms of computable vev/source pairs.
© 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
1. Introduction
Many systems in nature exhibit critical points with non-
relativistic
scale invariance. Such systems typically have Lifshitz
symmetries, which include anisotropic scaling between time and
space, characterized by a dynamical critical exponent z. A larger
symmetry group that also displays non-relativistic scale invari-
ance,
which contains the Lifshitz group, is the Schrödinger group
which possesses as additional symmetries the Galilean boosts and
a particle number symmetry. Over the last six years, following the
success of holography in describing strongly coupled relativistic
field theories, there has been a growing interest in applying sim-
ilar
techniques to strongly coupled systems with non-relativistic
symmetries [1–4]. In this letter we show that, when applying
holography to asymptotically locally Lifshitz space–times, the re-
sulting
dual field theories exhibit Schrödinger invariance.
Our
development builds on the recent works [5,6] in which, for
a specific action supporting z = 2 Lifshitz geometries, the Lifshitz
UV completion was identified by solving for the most general so-
lution
near the Lifshitz boundary. A key ingredient in these works
is the use of a vielbein formalism enabling the identification of
all the sources as the leading components of well-chosen bulk
fields. This includes in particular two linear combinations of the
timelike vielbein and the bulk gauge field, where one asymptotes
*
Corresponding author.
E-mail
addresses: hartong@nbi.dk (J. Hartong), kiritsis@physics.uoc.gr (E. Kiritsis),
obers@nbi.dk (N.A. Obers).
to the boundary timelike vielbein and the other to the boundary
gauge field. The latter plays a crucial role in the resulting geom-
etry
that is induced from the bulk onto the boundary, which in
[5,6] was shown to be a novel extension of Newton–Cartan geom-
etry
with a specific torsion tensor, called torsional Newton–Cartan
(TNC) geometry. By considering the coupling of this geometry to
the boundary field theory, the vevs dual to the sources were com-
puted
and moreover their Ward identities were written down in a
TNC covariant form. Among others, this includes the gauge invari-
ant
boundary energy–momentum tensor, from which the energy
density, momentum flux, energy flux and stress can be computed
by appropriate tangent space projections.
We
consider in this work a large class of Lifshitz models for
arbitrary values of z (focusing on 1 < z ≤ 2), where we find that
the above results generalize, and moreover that there is an un-
derlying
Schrödinger symmetry that acts on the sources and vevs,
revealing that the boundary theory has a Schrödinger invariance.
The arguments of this letter are furthermore supported by a com-
plementary
analysis of bulk versus boundary Killing symmetries
in [7]. This approach employs the TNC analogue of a conformal
Killing vector, which was identified for the first time in [6] by de-
riving
the conditions for the boundary theory to admit conserved
currents. We also note that details of the present work and [7]
along
with further results are given in [8,9]. Finally in a compan-
ion
paper [10] it is shown how to obtain all the details of the TNC
geometry by gauging the Schrödinger algebra. The notation among
the papers [7,10,8,9] together with the current one is fully com-
patible.
http://dx.doi.org/10.1016/j.physletb.2015.05.010
0370-2693/
© 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by
SCOAP
3
.