Christopher P. Herzog, Mukund
Rangamani, Simon F. Ross talk with ScienceWatch.com
and answer a few questions about this month's New Hot Papers in
the field of *Physics.

Article Title: Heating up Galilean
holography
Authors: Herzog, CP;Rangamani, M;Ross,
SF
Journal: J HIGH ENERGY PHYS, Volume: (11), Page: art. no.-080,
Year: NOV 2008
* Princeton Univ, Dept Phys, Princeton, NJ 08544 USA.
* Princeton Univ, Dept Phys, Princeton, NJ 08544 USA.
* Univ Durham, Ctr Particle Theory, Durham DH1 3LE,
England.
* Univ Durham, Dept Math Sci, Sci Labs, Durham DH1 3LE,
England.

*Note: two articles for
the field of Physics were tied by total citations in this
month's New Hot Papers.

Why do you think your paper is highly
cited?

There has been considerable excitement recently about applying techniques
from string theory to condensed matter systems. Our work was a contribution
to this activity, helping to open up a new line of research involving a new
class of symmetries which are important in condensed matter physics. The
fact that we provide a technique for constructing solutions has also led to
many papers applying this technique.

It is worth noting that similar work was performed simultaneously by other
groups (Allan Adams, Koushik Balasubramanian, and John McGreevy, "Hot
spacetimes for cold atoms," JHEP:11, article 059, 2008; and Juan
Maldacena, Dario Martelli, and Yuji Tachikawa, "Comments on string theory
backgrounds with non-relativistic conformal symmetry," JHEP:10,
article 072, 2008).

Does it describe a new discovery, methodology, or
synthesis of knowledge?

Coauthor:
Mukund Rangamani

Coauthor:
Simon F. Ross

Our paper represents both a new discovery (that these new symmetries are
realized in string theory) and a methodology (a solution-generating
technique for constructing geometries describing non-trivial states in a
theory with this symmetry).

Would you summarize the significance of your paper
in layman's terms?

Atomic physicists working the lab with dilute gases of atoms such as
lithium-6 have made an interesting strongly interacting form of matter
called fermions at unitarity. It is notoriously difficult to gain a good
theoretical understanding of strongly interacting systems.

It is believed that the large-scale dynamics of such materials under
certain conditions can have a simple description, in terms of a continuum
theory where the results of measurements are independent of the length
scale on which measurements are made (a conformal field theory).

In string theory, it is understood that some conformal field theories with
strong interactions have an effective description in terms of a
gravitational theory in one higher dimension (this relation is referred to
as a holographic duality).

This had been understood for conformal field theories where the scale
symmetry treats the time and spatial directions in the same way, and many
tests of this duality in particular cases have been performed.

Our work was inspired by an earlier proposal of Dam T. Son, Koushik
Balasubramanian, and John McGreevy to extend the holographic picture to
theories where the scale symmetry treats the time and spatial directions
differently (an anisotropic scaling symmetry).

We showed how such scalings could arise in string theory, and, in
particular, were able to construct solutions describing theories with
anisotropic scaling symmetry by a mapping on the space of solutions to
string theory (a solution-generating transformation).

This solution-generating transformation enabled us to construct a
gravitational solution corresponding to the field theory at non-zero
temperature, and extract predictions for the behavior of the theory at
finite temperature. We were thereby able to considerably extend the
understanding of the duality for this interesting new class of theories.

How did you become involved in this research, and
were there any problems along the way?

We became involved when we realized that the geometries with the required
symmetries were closely related to solutions in string theory some of us
had studied earlier, which led us to expect that they could be constructed
by solution-generating transformations.

This worked out pretty much as expected with no real difficulties, but
understanding the physics of the finite-temperature solutions was more
difficult, and we got stuck on parts of that calculation for some time.

Where do you see your research leading in the
future?

Further work on the gravitational description of these anisotropic scaling
symmetries should shed light on condensed matter physics or, at least, on
the general properties of strongly coupled field theories. Studying these
new examples can also help us to better understand the general features of
the relations between field theories and the dual gravitational
description.

Do you foresee any social or political
implications for your research?

No; this is purely theoretical research.

Christopher P. Herzog, Ph.D.
Department of Physics
Princeton University
Princeton, NJ, USA Web

Mukund Rangamani, Ph.D.
Department of Mathematical Sciences
Durham University
Durham, UK Web

Professor Simon F. Ross
Department of Mathematical Sciences
Durham University
Durham, UK Web

KEYWORDS: ADS-CFT CORRESPONDENCE; BLACK HOLES IN STRING THEORY;
FIELD-THEORY; SUPERGRAVITY; WAVES; GAS.