666 research outputs found
Constraints on Conformal Windows from Holographic Duals
We analyze a beta function with the analytic form of
Novikov-Shifman-Vainshtein-Zakharov result in the five dimensional
gravity-dilaton environment. We show how dilaton inherits poles and fixed
points of such beta function through the zeros and points of extremum in its
potential. Super Yang-Mills and supersymmetric QCD are studied in detail and
Seiberg's electric-magnetic duality in the dilaton potential is explicitly
demonstrated. Non-supersymmetric proposals of similar functional form are
tested and new insights into the conformal window as well as determinations of
scheme-independent value of the anomalous dimension at the fixed point are
presented.Comment: Fig. 5b is corrected to match the discussion in the tex
Torsional Newton Cartan gravity from non-relativistic strings
We study propagation of closed bosonic strings in torsional Newton-Cartan
geometry based on a recently proposed Polyakov type action derived by
dimensional reduction of the ordinary bosonic string along a null direction. We
generalize the Polyakov action proposal to include matter, i.e. the 2-form and
the 1-form that originates from the Kalb-Ramond field and the dilaton. We
determine the conditions for Weyl invariance which we express as the
beta-function equations on the worldsheet, in analogy with the usual case of
strings propagating on a pseudo-Riemannian manifold. The critical dimension of
the TNC space-time turns out to be 25. We find that Newton's law of gravitation
follows from the requirement of quantum Weyl invariance in the absence of
torsion. Presence of the 1-form requires torsion to be non vanishing. Torsion
has interesting consequences, in particular it yields a mass term and an
advection term in the generalized Newton's law. U(1) mass invariance of the
theory is an important ingredient in deriving the beta functions.Comment: Summary of results added. Reorganization and generalization of
results. Typos fixe
The Penrose limit of AdS*S space and holography
In the Penrose limit, AdS*S space turns into a Cahen-Wallach (CW) space whose
Killing vectors satisfy a Heisenberg algebra. This algebra is mapped onto the
holographic screen on the boundary of AdS. I show that the Heisenberg algebra
on the boundary of AdS may be obtained directly from the CW space by
appropriately constraining the states defined on it. The transformations
generated by the constraint are similar to gauge transformations. The
``holographic screen'' on the CW space is thus obtained as a ``gauge-fixing''
condition.Comment: 12 pages, improved discussion, to appear in Mod. Phys. Lett.
Effective Capacity in Broadcast Channels with Arbitrary Inputs
We consider a broadcast scenario where one transmitter communicates with two
receivers under quality-of-service constraints. The transmitter initially
employs superposition coding strategies with arbitrarily distributed signals
and sends data to both receivers. Regarding the channel state conditions, the
receivers perform successive interference cancellation to decode their own
data. We express the effective capacity region that provides the maximum
allowable sustainable data arrival rate region at the transmitter buffer or
buffers. Given an average transmission power limit, we provide a two-step
approach to obtain the optimal power allocation policies that maximize the
effective capacity region. Then, we characterize the optimal decoding regions
at the receivers in the space spanned by the channel fading power values. We
finally substantiate our results with numerical presentations.Comment: This paper will appear in 14th International Conference on
Wired&Wireless Internet Communications (WWIC
Improved Holographic QCD
We provide a review to holographic models based on Einstein-dilaton gravity
with a potential in 5 dimensions. Such theories, for a judicious choice of
potential are very close to the physics of large-N YM theory both at zero and
finite temperature. The zero temperature glueball spectra as well as their
finite temperature thermodynamic functions compare well with lattice data. The
model can be used to calculate transport coefficients, like bulk viscosity, the
drag force and jet quenching parameters, relevant for the physics of the
Quark-Gluon Plasma.Comment: LatEX, 65 pages, 28 figures, 9 Tables. Based on lectures given at
several Schools. To appear in the proceedinds of the 5th Aegean School
(Milos, Greece
pp-waves in 11-dimensions with extra supersymmetry
The Killing spinor equations for pp-wave solutions of eleven dimensional
supergravity are analysed and it is shown that there are solutions that
preserve 18,20,22 and 24 supersymmetries, in addition to the generic solution
preserving 16 supersymmetries and the Kowalski-Glikman solution preserving 32
supersymmetries.Comment: 13 pages. Reference added, typos corrected, new examples of
7-parameter case presente
The Bethe-Ansatz for N=4 Super Yang-Mills
We derive the one loop mixing matrix for anomalous dimensions in N=4 Super
Yang-Mills. We show that this matrix can be identified with the Hamiltonian of
an integrable SO(6) spin chain with vector sites. We then use the Bethe ansatz
to find a recipe for computing anomalous dimensions for a wide range of
operators. We give exact results for BMN operators with two impurities and
results up to and including first order 1/J corrections for BMN operators with
many impurities. We then use a result of Reshetikhin's to find the exact
one-loop anomalous dimension for an SO(6) singlet in the limit of large bare
dimension. We also show that this last anomalous dimension is proportional to
the square root of the string level in the weak coupling limit.Comment: 35 pages, 3 figures, LaTeX; v2 references added, typos corrected,
\Lambda fixed; v3 expanded discussion of higher loops in conclusion, matches
published versio
Orbiting Membranes in M-theory on AdS_7 x S^4 Background
We study classical solutions describing rotating and boosted membranes on
AdS_7 x S^4 background in M-theory. We find the dependence of the energy on the
spin and R-charge of these solutions. In the flat space limit we get E ~
S^{2/3}, while for AdS at leading order E-S grows as S^{1/3}. The membranes on
AdS_4 x S^7 background have briefly been studied as well.Comment: 13 pages, latex, v2: a note and refs. added, some typos correcte
Ethyl 4-(2-furÂyl)-2-oxochroman-3-carboxylÂate
The title compound, C16H14O5, was prepared from the reaction of 3-carbethoxyÂcoumarin with furan in the presence of AlCl3 as catalyst. In the crystal, interÂmolecular C—H⋯O hydrogen-bonding interÂactions between four molÂecules lead to a tetraÂmer in the unit cell. The furan ring is antiÂperiplanar [C—C—C—O = 167.9 (13)°] and the ethoxyÂcarbonyl group is (−)antiÂclinal [C—C—C—O = −128.6 (14)°] to the lactone ring
Marginal deformation of N=4 SYM and Penrose limits with continuum spectrum
We study the Penrose limit about a null geodesic with 3 equal angular momenta
in the recently obtained type IIB solution dual to an exactly marginal
-deformation of N=4 SYM. The resulting background has non-trivial NS
3-form flux as well as RR 5- and 3-form fluxes. We quantise the light-cone
Green-Schwarz action and show that it exhibits a continuum spectrum. We show
that this is related to the dynamics of a charged particle moving in a Landau
plane with an extra interaction induced by the deformation. We interpret the
results in the dual N=1 SCFT.Comment: 26 pages, 2 figures; v2: typos corrected, field theory interpretation
extende
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