660 research outputs found

### Matching the circular Wilson loop with dual open string solution at 1-loop in strong coupling

We compute the 1-loop correction to the effective action for the string
solution in AdS_5 x S^5 dual to the circular Wilson loop. More generically, the
method we use can be applied whenever the two dimensional spectral problem
factorizes, to regularize and define the fluctuation determinants in terms of
solutions of one-dimensional differential equations. A such it can be applied
to non-homogeneous solutions both for open and closed strings and to various
boundary conditions. In the case of the circular Wilson loop, we obtain, for
the 1-loop partition function a result which up to a factor of two matches the
expectation from the exact gauge theory computation. The discrepancy can be
attributed to an overall constant in the string partition function coming from
the normalization of zero modes, which we have not fixed.Comment: 32 pages; v2: typos corrected, acknowledgments added; v3: minor
corrections, references adde

### Spiky strings, light-like Wilson loops and pp-wave anomaly

We consider rigid rotating closed strings with spikes in AdS5 dual to certain
higher twist operators in N=4 SYM theory. In the limit of large spin when the
spikes reach the boundary of AdS5, the solutions with different numbers of
spikes are related by conformal transformations, implying that their energy is
determined by the same function of the `t Hooft coupling f(lambda) that appears
in the anomalous dimension of twist 2 operators or in the cusp anomaly. In the
limit when the number of spikes goes to infinity, we find an equivalent
description in terms of a string moving in an AdS pp-wave background. From the
boundary theory point of view, the corresponding description is based on the
gauge theory living in a 4d pp-wave space. Then, considering a charge moving at
the speed of light, or a null Wilson line, we find that the integrated energy
momentum tensor has a logarithmic UV divergence whose coefficient we call the
"pp-wave anomaly". The AdS/CFT correspondence implies that, for N=4 SYM, this
pp-wave anomaly should have the same value as the cusp anomaly. We verify this
at lowest order in SYM perturbation theory. As a side result of our string
theory analysis, we find new open string solutions in the Poincare patch of the
standard AdS space which end on a light-like Wilson line and also in two
parallel light-like Wilson lines at the boundary.Comment: 28 pages, 2 eps figures, LaTeX. v2: typos correcte

### Meson mass and confinement force driven by dilaton

Meson spectra given as fluctuations of a D7 brane are studied under the
background driven by the dilaton. This leads to a dual gauge theory with quark
confinement due to the gauge condensate. We find that the effect of the gauge
condensate on the meson spectrum is essential in order to make a realistic
hadron spectrum in the non-supersymmetric case. In the supersymmetric case,
however, only the spectra of the scalars are affected, but they are changed in
an opposite way compared to the non-supersymmetric case.Comment: 11 pages, 2 figure

### Collective Dynamics of Solitons and Inequivalent Quantizations

The collective dynamics of solitons with a coset space G/H as moduli space is
studied. It is shown that the collective band for a vibrational state is given
by the inequivalent coset space quantization corresponding to the
representation of H carried by the vibration.Comment: 6 pages, revte

### Aspects of the Screening Length and Drag Force in Two Alternative Gravity Duals of the Quark-gluon Plasma

We compute the screening length of mesons with different angular momentum $J$
from two gravity dual theories. Both the asymptotically $AdS_{5}$ and
Sakai-Sugimoto metrics are considered in the calculations. Using the dual
description of the quark as a classical string ending on the probe brane, we
obtain the interacting potential between the heavy quark and antiquark after
rotating the background metric. The result shows that the screening length of
mesons with different $J$ is well fit to $a_{J}/T$. The constant $a_{J}$ is
determined for $J=0,1,2$ by taking advantage of numerical techniques. Finally,
we calculate the drag force and relaxation times from the Sakai-Sugimoto metric
and compare with the ones obtained in the $AdS_{5}$. The application of our
result to charmonium and bottomonium at RHIC and LHC is briefly discussed.Comment: 18 pages, 6 figures, 2 tables, version to appear in JHEP,
acknowledgment adde

### Strong-coupling expansion of cusp anomaly and gluon amplitudes from quantum open strings in AdS_5 x S^5

An important ``observable'' of planar N=4 SYM theory is the scaling function
f(lambda) that appears in the anomalous dimension of large spin twist 2
operators and also in the cusp anomaly of light-like Wilson loops. The
non-trivial relation between the anomalous dimension and the Wilson
interpretations of f(lambda) is well-understood on the perturbative gauge
theory side of the AdS/CFT duality. In the first part of this paper we present
the dual string-theory counterpart of this relation, to all orders in
lambda^(-1/2) expansion. As a check, we explicitly compute the leading 1-loop
string sigma model correction to the cusp Wilson loop, reproducing the same
subleading coefficient in f(lambda) as found earlier in the spinning closed
string case. The same function f(lambda) appears also in the resummed form of
the 4-gluon amplitude as discussed at weak coupling by Bern, Dixon and Smirnov
and recently found at the leading order at strong coupling by Alday and
Maldacena (AM). Here we attempt to extend this approach to subleading order in
lambda^(-1/2) by computing the IR singular part of 1-loop string correction to
the corresponding T-dual Wilson loop. We discuss explicitly the 1-cusp case and
comment on apparent problems with the dimensional regularization proposal of AM
when directly applied order by order in strong coupling (inverse string
tension) expansion.Comment: 35 pages. v2: minor corrections, references adde

### Correspondence principle for a brane in Minkowski space and vector mesons

We consider a 3-brane of positive cosmological constant (de Sitter) in
D-dimensional Minkowski space. We show that the Poincare algebra in the bulk
yields a SO(4,2) algebra when restricted to the brane. In the limit of zero
cosmological constant (flat brane), this algebra turns into the conformal
algebra on the brane. We derive a correspondence principle for Minkowski space
analogous to the AdS/CFT correspondence. We discuss explicitly the cases of
scalar and gravitational fields. For a 3-brane of finite thickness in the
transverse directions, we obtain a spectrum for vector gravitational
perturbations which correspond to vector mesons. The spectrum agrees with the
one obtained in truncated AdS space by de Teramond and Brodsky provided D=10
and the bulk mass scale M is of order the geometric mean of the Planck mass
($\bar M$) on the brane and $\Lambda_{QCD}$ ($M \sim (\bar M
\Lambda_{QCD})^{1/2} \sim 10^9$ GeV).Comment: 8 pages in two-column ReVTeX

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