145 research outputs found
Spinning Pulsating String Solitons in AdS_5 x S^5
We point out the existence of some simple string solitons in AdS_5 x S^5,
which at the same time are spinning in AdS_5 and pulsating in S^5, or
vice-versa. This introduces an additional arbitrary constant into the scaling
relations between energy and spin or R-charge. The arbitrary constant is not an
angular momentum, but can be related to the amplitude of the pulsation. We
discuss the solutions in detail and consider the scaling relations. Pulsating
multi spin or multi R-charge solutions can also be constructed.Comment: 15 pages, Late
Open String Fluctuations in AdS with and without Torsion
The equations of motion and boundary conditions for the fluctuations around a
classical open string, in a curved space-time with torsion, are considered in
compact and world-sheet covariant form. The rigidly rotating open strings in
Anti de Sitter space with and without torsion are investigated in detail. By
carefully analyzing the tangential fluctuations at the boundary, we show
explicitly that the physical fluctuations (which at the boundary are
combinations of normal and tangential fluctuations) are finite, even though the
world-sheet is singular there. The divergent 2-curvature thus seems less
dangerous than expected, in these cases. The general formalism can be
straightforwardly used also to study the (bosonic part of the) fluctuations
around the closed strings, recently considered in connection with the AdS/CFT
duality, on AdS_5 \times S^5 and AdS_3 \times S^3 \times T^4.Comment: 19 pages, Late
Vector Bin Packing with Multiple-Choice
We consider a variant of bin packing called multiple-choice vector bin
packing. In this problem we are given a set of items, where each item can be
selected in one of several -dimensional incarnations. We are also given
bin types, each with its own cost and -dimensional size. Our goal is to pack
the items in a set of bins of minimum overall cost. The problem is motivated by
scheduling in networks with guaranteed quality of service (QoS), but due to its
general formulation it has many other applications as well. We present an
approximation algorithm that is guaranteed to produce a solution whose cost is
about times the optimum. For the running time to be polynomial we
require and . This extends previous results for vector
bin packing, in which each item has a single incarnation and there is only one
bin type. To obtain our result we also present a PTAS for the multiple-choice
version of multidimensional knapsack, where we are given only one bin and the
goal is to pack a maximum weight set of (incarnations of) items in that bin
Precision Spectroscopy of AdS/CFT
We extend recent remarkable progress in the comparison of the dynamical
energy spectrum of rotating closed strings in AdS_5xS^5 and the scaling weights
of the corresponding non-near-BPS operators in planar N=4 supersymmetric gauge
theory. On the string side the computations are feasible, using semiclassical
methods, if angular momentum quantum numbers are large. This results in a
prediction of gauge theory anomalous dimensions to all orders in the `t Hooft
coupling lambda. On the gauge side the direct computation of these dimensions
is feasible, using a recently discovered relation to integrable (super) spin
chains, provided one considers the lowest order in lambda. This one-loop
computation then predicts the small-tension limit of the string spectrum for
all (i.e. small or large) quantum numbers. In the overlapping window of large
quantum numbers and small effective string tension, the string theory and gauge
theory results are found to match in a mathematically highly non-trivial
fashion. In particular, we compare energies of states with (i) two large
angular momenta in S^5, and (ii) one large angular momentum in AdS_5 and S^5
each, and show that the solutions are related by an analytic continuation.
Finally, numerical evidence is presented on the gauge side that the agreement
persists also at higher (two) loop order.Comment: 26 pages, 1 figure, v2: typos correcte
Proof of the Julia-Zee Theorem
It is a well accepted principle that finite-energy static solutions in the
classical relativistic gauge field theory over the -dimensional
Minkowski spacetime must be electrically neutral. We call such a statement the
Julia--Zee theorem. In this paper, we present a mathematical proof of this
fundamental structural property
Mesons and baryons in a soft-wall holographic approach
We discuss a holographic soft-wall model developed for the description of
mesons and baryons with adjustable quantum numbers n, J, L, S. This approach is
based on an action which describes hadrons with broken conformal invariance and
which incorporates confinement through the presence of a background dilaton
field.Comment: 6 pages, Presented by Valery E. Lyubovitskij at LIGHTCONE 2011, 23 -
27 May, 2011, Dalla
Radiative Correction to the Dirichlet Casimir Energy for Theory in Two Spatial Dimensions
In this paper, we calculate the next to the leading order Casimir energy for
real massive and massless scalar fields within theory,
confined between two parallel plates with the Dirichlet boundary condition in
two spatial dimensions. Our results are finite in both cases, in sharp contrast
to the infinite result reported previously for the massless case. In this paper
we use a renormalization procedure introduced earlier, which naturally
incorporates the boundary conditions. As a result our radiative correction term
is different from the previously calculated value. We further use a
regularization procedure which help us to obtain the finite results without
resorting to any analytic continuation techniques.Comment: 8 pages, 3 figure
Deep inelastic scattering of baryons in a modified soft wall model
We calculate the structure functions for unpolarized deep inelastic
scattering of baryons using an AdS/QCD soft wall model that considers a dressed
mass for the bulk fermionic fields. Considering the regime of large Bjorken
parameter x, we compare the results for the proton structure function
with experimental results.Comment: We improved the comparison with experimental data and included more
references, version to appear in EPJ
Boson-fermion unification, superstrings, and Bohmian mechanics
Bosonic and fermionic particle currents can be introduced in a more unified
way, with the cost of introducing a preferred spacetime foliation. Such a
unified treatment of bosons and fermions naturally emerges from an analogous
superstring current, showing that the preferred spacetime foliation appears
only at the level of effective field theory, not at the fundamental superstring
level. The existence of the preferred spacetime foliation allows an objective
definition of particles associated with quantum field theory in curved
spacetime. Such an objective definition of particles makes the Bohmian
interpretation of particle quantum mechanics more appealing. The superstring
current allows a consistent Bohmian interpretation of superstrings themselves,
including a Bohmian description of string creation and destruction in terms of
string splitting. The Bohmian equations of motion and the corresponding
probabilistic predictions are fully relativistic covariant and do not depend on
the preferred foliation.Comment: 30 pages, 1 figure, revised, to appear in Found. Phy
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
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