110 research outputs found
A note on the universality of the Hagedorn behavior of pp-wave strings
Following on from recent studies of string theory on a one-parameter family
of integrable deformations of proposed by Lunin and
Maldacena, we carry out a systematic analysis of the high temperature
properties of type IIB strings on the associated pp-wave geometries. In
particular, through the computation of the thermal partition function and free
energy we find that not only does the theory exhibit a Hagedorn transition in
both the and class of pp-waves, but that the Hagedorn
temperature is insensitive to the deformation suggesting an interesting
universality in the high temperature behaviour of the pp-wave string theory. We
comment also on the implications of this universality on the
confinement/deconfinement transition in the dual
Leigh-Strassler deformation of Yang-Mills theory.Comment: 25 pages; fixed minor typo; added reference
Integrable twists in AdS/CFT
A class of marginal deformations of four-dimensional N=4 super Yang-Mills
theory has been found to correspond to a set of smooth, multiparameter
deformations of the S^5 target subspace in the holographic dual on AdS_5 x S^5.
We present here an analogous set of deformations that act on global toroidal
isometries in the AdS_5 subspace. Remarkably, certain sectors of the string
theory remain classically integrable in this larger class of so-called
gamma-deformed AdS_5 x S^5 backgrounds. Relying on studies of deformed
su(2)_gamma models, we formulate a local sl(2)_gamma Lax representation that
admits a classical, thermodynamic Bethe equation (based on the Riemann-Hilbert
interpretation of Bethe's ansatz) encoding the spectrum in the deformed AdS_5
geometry. This result is extended to a set of discretized, asymptotic Bethe
equations for the twisted string theory. Near-pp-wave energy spectra within
sl(2)_gamma and su(2)_gamma sectors provide a useful and stringent test of such
equations, demonstrating the reliability of this technology in a wider class of
string backgrounds. In addition, we study a twisted Hubbard model that yields
certain predictions of the dual beta-deformed gauge theory.Comment: v2: references and clarifications added, 46 page
Giants On Deformed Backgrounds
We study giant graviton probes in the framework of the three--parameter
deformation of the AdS_5 x S^5 background. We examine both the case when the
brane expands in the deformed part of the geometry and the case when it blows
up into AdS. Performing a detailed analysis of small fluctuations around the
giants, the configurations turn out to be stable. Our results hold even for the
supersymmetric Lunin-Maldacena deformation.Comment: LaTex, 28 pages, uses JHEP3; v2: minor corrections, references added;
v3: final version accepted for publication in JHE
Open Spinning Strings and AdS/dCFT Duality
We consider open spinning string solutions on an AdS_4 x S^2-brane (D5-brane)
in the bulk AdS_5 x S^5 background. By taking account of the breaking of
SO(6)_R to SO(3)_H x SO(3)_V due to the presence of the AdS-brane, the open
rotating string ansatz is discussed. We construct the elliptic folded/circular
open string solutions in the SU(2) and the SL(2) sectors, so that they satisfy
the appropriate boundary conditions. On the other hand, in the SU(2) sector of
the gauge theory, we compute the matrix of anomalous dimension of the defect
operator, which turns out to be the Hamiltonian of an open integrable spin
chain. Then we consider the coordinate Bethe ansatz with arbitrary number of
impurities, and compare the boundary condition of the Bethe wavefunction with
that of the corresponding open string solution. We also discuss the Bethe
ansatz for the open SL(2) spin chain with several supports from the string
theory side. Then, in both SU(2) and SL(2) sectors, we analyze the Bethe
equations in the thermodynamic limit and formulate the `doubling trick' on the
Riemann surface associated with the gauge theory.Comment: 1+50 pages, 7 figures, JHEP style, references adde
BPS Operators in N=4 SYM: Calogero Models and 2D Fermions
A connection between the gauge fixed dynamics of protected operators in
superconformal Yang-Mills theory in four dimensions and Calogero systems is
established. This connection generalizes the free Fermion description of the
chiral primary operators of the gauge theory formed out of a single complex
scalar to more general operators. In particular, a detailed analysis of
protected operators charged under an su(1|1)contained in psu(2,2|4) is carried
out and a class of operators is identified, whose dynamics is described by the
rational super-Calogero model. These results are generalized to arbitrary BPS
operators charged under an su(2|3) of the superconformal algebra. Analysis of
the non-local symmetries of the super-Calogero model is also carried out, and
it is shown that symmetry for a large class of protected operators is a
contraction of the corresponding Yangian algebra to a loop algebra.Comment: 29 pages, 3 figure
Rotating Strings with Two Unequal Spins in Lunin-Maldacena Background
We study a string motion in the Lunin-Maldacena background, that is, the
\beta-deformed AdS_5 \times \tilde{S}^5 background dual to a \beta-deformation
of \mathcal{N} = 4 super Yang-Mills theory. For real \beta we construct a
rotating and wound string solution which has two unequal spins in \tilde{S}^5.
The string energy is expressed in terms of the spins, the winding numbers and
the deformation parameter. In the expansion of \lambda/J^2 with the total spin
J and the string tension \sqrt{\lambda} we present ``one-loop" and ``two-loop"
energy corrections. The ``one-loop" one agrees with the one-loop anomalous
dimension of the corresponding gauge-theory scalar operators obtained in
hep-th/0503192 from the \beta-deformed Bethe equation as well as the
anisotropic Landau-Lifshitz equation.Comment: 13 pages, LaTeX, no figure
Convex central configurations of the 4-body problem with two pairs of equal masses
Agraïments: The first and third authors are partially supported by FAPEMIG grant APQ-001082/14. The third author is partially supported by CNPq grant 472321/2013-7 and by FAPEMIG grant PPM-00516-15. The second and third autors are supported by CAPES CSF-PVE grant 88881.030454/2013-01.MacMillan and Bartky in 1932 proved that there is a unique isosceles trapezoid central configuration of the 4--body problem when two pairs of equal masses are located at adjacent vertices. After this result the following conjecture was well known between people working on central configurations: The isosceles trapezoid is the unique convex central configuration of the planar 4--body problem when two pairs of equal masses are located at adjacent vertices. We prove this conjecture
Vacuum fluctuations and topological Casimir effect in Friedmann-Robertson-Walker cosmologies with compact dimensions
We investigate the Wightman function, the vacuum expectation values of the
field squared and the energy-momentum tensor for a massless scalar field with
general curvature coupling parameter in spatially flat
Friedmann-Robertson-Walker universes with an arbitrary number of toroidally
compactified dimensions. The topological parts in the expectation values are
explicitly extracted and in this way the renormalization is reduced to that for
the model with trivial topology. In the limit when the comoving lengths of the
compact dimensions are very short compared to the Hubble length, the
topological parts coincide with those for a conformal coupling and they are
related to the corresponding quantities in the flat spacetime by standard
conformal transformation. In the opposite limit of large comoving lengths of
the compact dimensions, in dependence of the curvature coupling parameter, two
regimes are realized with monotonic or oscillatory behavior of the vacuum
expectation values. In the monotonic regime and for nonconformally and
nonminimally coupled fields the vacuum stresses are isotropic and the equation
of state for the topological parts in the energy density and pressures is of
barotropic type. In the oscillatory regime, the amplitude of the oscillations
for the topological part in the expectation value of the field squared can be
either decreasing or increasing with time, whereas for the energy-momentum
tensor the oscillations are damping.Comment: 20 pages, 2 figure
Green-Schwarz Strings in TsT-transformed backgrounds
We consider classical strings propagating in a background generated by a
sequence of TsT transformations. We describe a general procedure to derive the
Green-Schwarz action for strings. We show that the U(1) isometry variables of
the TsT-transformed background are related to the isometry variables of the
initial background in a universal way independent of the details of the
background. This allows us to prove that strings in the TsT-transformed
background are described by the Green-Schwarz action for strings in the initial
background subject to twisted boundary conditions. Our construction implies
that a TsT transformation preserves integrability properties of the string
sigma model. We discuss in detail type IIB strings propagating in the
\g_i-deformed AdS_5 x S^5 space-time, find the twisted boundary conditions for
bosons and fermions, and use them to write down an explicit expression for the
monodromy matrix. We also discuss string zero modes whose dynamics is governed
by a fermionicgeneralization of the integrable Neumann model.Comment: 33 pages, latex, v2: typos correcte
Splitting of Folded Strings in AdS_4*CP^3
We study classically splitting of two kinds of folded string solutions in
AdS_4*CP^3. Conserved charges of the produced fragments are computed for each
case. We find interesting patterns among these conserved charges.Comment: minor changes, 14 pages, no figure
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