We construct an analytic solution for a one-parameter family of holographic
superconductors in asymptotically Lifshitz spacetimes. We utilize this solution
to explore various properties of the systems such as (1) the superfluid phase
background an...

The Kibble-Zurek (KZ) mechanism describes the generations of topological
defects when a system undergoes a second-order phase transition via quenches.
We study the holographic KZ scaling using holographic superconductors. The
scaling can be unders...

It is known that time-dependent perturbations can enhance superconductivity
and increase the critical temperature. If this phenomenon happens to high-T_c
superconductors, one could obtain room-temperature superconductors, but this is
still an open...

We study the proposal by Bredberg et al. (1006.1902), where the fluid is
defined by the Brown-York tensor on a timelike surface at r=r_c in black hole
backgrounds. We consider both Rindler space and the Schwarzschild-AdS (SAdS)
black hole. The for...

We study the ratio of the shear viscosity to the entropy density for various
holographic superfluids. For the s-wave case, the ratio has the universal value
1/(4pi) as in various holographic models. For the p-wave case, there are two
shear viscosi...

We review black holes with second-order phase transition in string theory
(R-charged black holes and holographic superconductors) and review their static
and dynamic critical phenomena. Holographic superconductors have conventional
mean-field valu...

In the AdS/CFT duality, it is often said that a local symmetry in a bulk
theory corresponds to a global symmetry in the corresponding boundary theory,
but the global symmetry can become local when one couples with an external
source. As a result, ...

We investigate the vortex lattice solution in a (2+1)-dimensional holographic
model of superconductors constructed from a charged scalar condensate. The
solution is obtained perturbatively near the second-order phase transition and
is a holographi...

We study "holographic superconductors" in various spacetime dimensions. We
compute most of the static critical exponents in the linear perturbations and
show that they take the standard mean-field values. We also consider the
dynamic universality ...

In critical phenomena, singular behaviors arise not only for thermodynamic
quantities but also for transport coefficients. We study this dynamic critical
phenomenon in the AdS/CFT duality. We consider black holes with a single
R-charge in various ...

We obtain the relaxation time for the shear viscous stress for various
geometries using the "membrane paradigm" formula proposed recently. We consider
the generic Schwarzschild-AdS black holes (SAdS), the generic Dp-brane, the
Klebanov-Tseytlin (K...

We obtain new transport coefficients of causal hydrodynamics for the M2 and
the M5-brane using a Kubo-like formula proposed by Baier, Romatschke, Son,
Starinets, and Stephanov (arXiv:0712.2451 [hep-th]). The relaxation times agree
with the ones ob...

Phys.Rev.D77:066014,2008; Erratum-ibid.D78:089902,2008 Dec 2007

We study causal hydrodynamics (Israel-Stewart theory) of gauge theory plasmas
from the AdS/CFT duality. Causal hydrodynamics requires new transport
coefficients (relaxation times) and we compute them for a number of
supersymmetric gauge theories i...

This is a comment to hep-th/0703243. The paper determined the relaxation time
tau_pi of the shear viscous stress for the N=4 SYM from AdS/CFT correspondence.
The purpose of this comment is to point out that the value of tau_pi is 3 times
larger th...

We study the screening length of a heavy quark-antiquark pair in strongly
coupled gauge theory plasmas flowing at velocity v following a proposal by Liu,
Rajagopal, and Wiedemann. We analyze the screening length as the direction of
the plasma wind...

We review the AdS/CFT description of gauge theory plasmas for non-experts. We
discuss the low shear viscosity, jet quenching, and J/psi-suppression, which
are three major signatures for the quark-gluon plasma observed at RHIC
experiments.

We study the screening length L_s of a heavy quark-antiquark pair in strongly
coupled gauge theory plasmas flowing at velocity v. Using the AdS/CFT
correspondence we investigate, analytically, the screening length in the
ultra-relativistic limit. ...

In AdS/CFT duality, it is often argued that information behind the event
horizon is encoded even in boundary correlators. However, its implication is
not fully understood. We study a simple model which can be analyzed explicitly.
The model is a tw...

We compute the strong coupling limit of the shear viscosity for the N=4
super-Yang-Mill theory with a chemical potential. We use the five-dimensional
Reissner-Nordstrom-anti-deSitter black hole, so the chemical potential is the
one for the R-charg...

We re-examine physical state representations in the covariant quantization of
bosonic string. We especially consider one parameter family of gauge fixing
conditions for the residual gauge symmetry due to null states (or BRST exact
states), and obt...

The nonextreme Dp-brane solutions in type II supergravity(in the near-horizon
limit) are expected to be dual to (p+1)-dimensional noncompact supersymmetric
Yang-Mills theories at finite temperature. We study the translationally
invariant perturbat...

In our previous papers, we prove the no-ghost theorem without light-cone
directions (hep-th/0005002, hep-th/0303051). We point out that our results are
valid for more general backgrounds. In particular, we prove the no-ghost
theorem for AdS_3 in t...

It is well-known that the standard no-ghost theorem is valid as long as the
background has the light-cone directions. We prove the no-ghost theorem for the
NSR string when only the timelike direction is flat. This is done by the BRST
quantization,...

The enhancon mechanism is studied in the heterotic string theory. We consider
the N_L=0 winding strings with momentum (NS1-W*) and the Kaluza-Klein dyons
(KK5-NS5*). The NS1-W* and KK5-NS5* systems are dualized to the D4-D0* and
D6-D2* systems, re...

We review the current status of the singularity problem in string theory for
non-experts. After the problem is discussed from the point of view of
supergravity, we discuss classic examples and recent examples of singularity
resolution in string th...

It is well-known that the standard no-ghost theorem can be extended
straightforwardly to the general c=26 CFT on R^{d-1,1} \times K, where 2 \leq d
\leq 26 and K is a compact unitary CFT of appropriate central charge. We prove
the no-ghost theorem...

We propose that Strominger's method to derive the BTZ black hole entropy is
in fact applicable to other asymptotically AdS_3 black holes and gives the
correct functional form of entropies. We discuss various solutions in the
Einstein-Maxwell theor...

Strominger has derived the Bekenstein-Hawking entropy of the BTZ black hole
using asymptotic Virasoro algebra. We apply Strominger's method to a black hole
solution found by Martinez and Zanelli (MZ). This is a solution of
three-dimensional gravit...

We investigate the string theory on three dimensional black holes discovered
by Bañados, Teitelboim and Zanelli in the framework of conformal field
theory. The model is described by an orbifold of the WZW
model. The spect...

The WZW orbifold describes the (2+1)-dimensional black hole
which approaches anti-de~Sitter space asymptotically. We study the tachyon scattering off the rotating black hole background and
calculate the Hawking tempe...

We study the order correction to the string black hole found by
Garfinkle, Horowitz, and Strominger. We include all operators of dimension up
to four in the Lagrangian, and use the field redefinition technique which
facilitates the analy...

The matrix model is equivalent to dimensional string theory.
However, the tachyon self-interaction in the former is local, while in the
latter it is nonlocal due to the gravitational, dilaton and higher string
fields. By studying scatt...

For string theory, the perturbative -matrices are not well-defined
due to a zero mode divergence. Although there exist formal procedures to make
the integral convergent, their physical meanings are unclear. We describe a
method to obtain f...

The similarity between tree-level string theory scalar amplitudes, the
Koba-Nielsen form () and the Virasoro-Shapiro form () suggests a
natural generalization for a scalar amplitude. It is shown that the
amplitude sha...

This is the draft/updated version of a textbook on "real-world" applications
of the AdS/CFT duality for beginning graduate students in particle physics and
for researchers in the other fields. The aim of this book is to provide
background material...

According to string theory, there is an intimate relation between a gauge theory and a black hole. Thus, gauge theory plasmas have been studied using black holes. In the meantime, quark-gluon plasma experiments have been done by the RHIC machine a...

We review the AdS/CFT description of gauge theory plasmas. We discuss the low shear viscosity, the jet quenching, and the J/ψ-suppression, which are three major signatures for the quark-gluon plasma observed at RHIC experiments.