6 research outputs found
Rotating Strings in Confining AdS/CFT Backgrounds
We study semiclassical rotating strings in AdS/CFT backgrounds that exhibit
both confinement and finite-size effects. The energy versus spin dispersion
relation for short strings is the expected Regge trajectory behaviour, with the
same string tension as is measured by the Wilson loop. Long strings probe the
interplay between confinement and finite-size effects. In particular, the
dispersion relation for long strings shows a characteristic dependence on the
string tension and the finite-size scale.Comment: 18 pages, 3 figures. v2: minor changes, refs. adde
Orbiting strings in AdS black holes and N=4 SYM at finite temperature
Following Gubser, Klebanov and Polyakov [hep-th/0204051], we study strings in
AdS black hole backgrounds. With respect to the pure AdS case, rotating strings
are replaced by orbiting strings. We interpret these orbiting strings as CFT
states of large spin similar to glueballs propagating through a gluon plasma.
The energy and the spin of the orbiting string configurations are associated
with the energy and the spin of states in the dual finite temperature N=4 SYM
theory. We analyse in particular the limiting cases of short and long strings.
Moreover, we perform a thermodynamic study of the angular momentum transfer
from the glueball to the plasma by considering string orbits around rotating
AdS black holes. We find that standard expectations, such as the complete
thermal dissociation of the glueball, are borne out after subtle properties of
rotating AdS black holes are taken into account.Comment: 17 pages, 1 figure. v2,3 minor refinements. JHEP versio
A note on the extensivity of the holographic entanglement entropy
We consider situations where the renormalized geometric entropy, as defined
by the AdS/CFT ansatz of Ryu and Takayanagi, shows extensive behavior in the
volume of the entangled region. In general, any holographic geometry that is
`capped' in the infrared region is a candidate for extensivity provided the
growth of minimal surfaces saturates at the capping region, and the induced
metric at the `cap' is non-degenerate. Extensivity is well-known to occur for
highly thermalized states. In this note, we show that the holographic ansatz
predicts the persistence of the extensivity down to vanishing temperature, for
the particular case of conformal field theories in 2+1 dimensions with a
magnetic field and/or electric charge condensates.Comment: 12 pages and 2 figures; one reference added; Significant additions to
section 3, involving new results and a more pedagogical presentatio
Closed-String Tachyons and the Hagedorn Transition in AdS Space
We discuss some aspects of the behaviour of a string gas at the Hagedorn
temperature from a Euclidean point of view. Using AdS space as an infrared
regulator, the Hagedorn tachyon can be effectively quasi-localized and its
dynamics controled by a finite energetic balance. We propose that the off-shell
RG flow matches to an Euclidean AdS black hole geometry in a generalization of
the string/black-hole correspondence principle. The final stage of the RG flow
can be interpreted semiclassically as the growth of a cool black hole in a
hotter radiation bath. The end-point of the condensation is the large Euclidean
AdS black hole, and the part of spacetime behind the horizon has been removed.
In the flat-space limit, holography is manifest by the system creating its own
transverse screen at infinity. This leads to an argument, based on the
energetics of the system, explaining why the non-supersymmetric type 0A string
theory decays into the supersymmetric type IIB vacuum. We also suggest a notion
of `boundary entropy', the value of which decreases along the line of flow.Comment: 24 pages, Harvmac. 2 Figures. Typos corrected and reference adde
Holographic entanglement entropy probes (non)locality
We study the short-distance structure of geometric entanglement entropy in
certain theories with a built-in scale of nonlocality. In particular we examine
the cases of Little String Theory and Noncommutative Yang-Mills theory, using
their AdS/CFT descriptions. We compute the entanglement entropy via the
holographic ansatz of Ryu and Takayanagi to conclude that the area law is
violated at distance scales that sample the nonlocality of these models, being
replaced by an extensive volume law. In the case of the noncommutative model,
the critical length scale that reveals the area/volume law transition is
strongly affected by UV/IR mixing effects. We also present an argument showing
that Lorentz symmetry tends to protect the area law for theories with
field-theoretical density of states.Comment: 24 pages and 8 figures; added references, corrected some typos and
added a full NEW SECTION with an explicit result linking holography, Lorentz
invariance and area law of entanglement entrop