747 research outputs found
Data dependence results of a new multistep and S-iterative schemes for contractive-like operators
In this paper, we prove that convergence of a new iteration and S-iteration
can be used to approximate to the fixed points of contractive-like operators.
We also prove some data dependence results of this new iteration and
S-iteration schemes for contractive-like operators. Our results extend and
improve some known results in the literature.Comment: arXiv admin note: text overlap with arXiv:1211.570
Conductance properties of rough quantum wires with colored surface disorder
Effects of correlated disorder on wave localization have attracted
considerable interest. Motivated by the importance of studies of quantum
transport in rough nanowires, here we examine how colored surface roughness
impacts the conductance of two-dimensional quantum waveguides, using direct
scattering calculations based on the reaction matrix approach. The
computational results are analyzed in connection with a theoretical relation
between the localization length and the structure factor of correlated
disorder. We also examine and discuss several cases that have not been treated
theoretically or are beyond the validity regime of available theories. Results
indicate that conductance properties of quantum wires are controllable via
colored surface disorder.Comment: 19 pages, 7 figure
Thermodynamics of AdS/QCD within the 5D dilaton-gravity model
We calculate the pressure, entropy density, trace anomaly and speed of sound
of the gluon plasma using the dilaton potential of Ref. arXiv:0911.0627[hep-ph]
in the dilaton-gravity theory of AdS/QCD. The finite temperature observables
are calculated from the Black Hole solutions of the Einstein equations, and
using the Bekenstein-Hawking equality of the entropy with the area of the
horizon. Renormalization is well defined, because the T=0 theory has asymptotic
freedom. Comparison with lattice simulations is made.Comment: 4 pages, 4 figures. To appear in the proceedings of 15th
International Conference in Quantum Chromodynamics (QCD 10), Montpellier,
France, 28 Jun - 3 Jul 201
Phenomenology of AdS/QCD and Its Gravity Dual
We construct the dilaton potential in the gravity dual theory of AdS/QCD for
the warp factor of Refs.{1,2}. Using this AdS_5-metric with properties similar
to QCD, we find that the gravity dual leads to a meaningful gauge coupling in
the region between the charmonium and bottonium mass, but differs slightly from
QCD in the extreme UV. When we fix the ultraviolet behavior in accord with the
beta-function, we can obtain good agreement with the overall heavy
quark-antiquark potential. Although the leading order proportional to
-\alpha^{4/3}/r differs from perturbative QCD, the full potential agrees quite
well with the short distance QCD potential in NNLO.Comment: 42 pages, 13 figures, 1 tabl
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
Polyakov Loops in Strongly-Coupled Plasmas with Gravity Duals
We study the properties of the Polyakov loop in strongly-coupled gauge
plasmas that are conjectured to be dual to five dimensional theories of gravity
coupled to a nontrivial single scalar field. We find a gravity dual that can
describe the thermodynamic properties and also the expectation value of the
Polyakov loop in the deconfined phase of quenched SU(3) QCD up to .Comment: 7 pages, 2 figures, talk presented at the International Conference on
Strangeness in Quark Matter, Buzios, Rio de Janeiro, Brazil, Sept. 27 - oct.
2, 200
Dressed spectral densities for heavy quark diffusion in holographic plasmas
We analyze the large frequency behavior of the spectral densities that govern
the generalized Langevin diffusion process for a heavy quark in the context of
the gauge/gravity duality. The bare Langevin correlators obtained from the
trailing string solution have a singular short-distance behavior. We argue that
the proper dressed spectral functions are obtained by subtracting the
zero-temperature correlators. The dressed spectral functions have a
sufficiently fast fall-off at large frequency so that the Langevin process is
well defined and the dispersion relations are satisfied. We identify the cases
in which the subtraction does not modify the associated low-frequency transport
coefficients. These include conformal theories and the non-conformal,
non-confining models. We provide several analytic and numerical examples in
conformal and non-conformal holographic backgrounds.Comment: 51 pages, 2 figure
Improved Holographic Yang-Mills at Finite Temperature: Comparison with Data
The semi-phenomenological improved holographic model for QCD is confronted
with data of the pure glue, large-Nc gauge theory. After fitting two
phenomenological parameters in the potential, the model can reproduce in detail
all thermodynamic functions at finite temperature. It also reproduces in detail
all known spin-0 and spin-2 glueball observables at zero temperature and
predicts the rest of the 0++ and 2++ towers. A similar two parameter fit in the
CP-odd sector postdicts the correct second 0+- glueball mass, and predicts the
rest of the 0+- tower.Comment: 36 pages, 10 figures; references added, minor typos corrected; v3:
corrected numerical mistake in section 5.4
Holography and Thermodynamics of 5D Dilaton-gravity
The asymptotically-logarithmically-AdS black-hole solutions of 5D dilaton
gravity with a monotonic dilaton potential are analyzed in detail. Such
theories are holographically very close to pure Yang-Mills theory in four
dimensions. The existence and uniqueness of black-hole solutions is shown. It
is also shown that a Hawking-Page transition exists at finite temperature if
and only if the potential corresponds to a confining theory. The physics of the
transition matches in detail with that of deconfinement of the Yang-Mills
theory. The high-temperature phase asymptotes to a free gluon gas at high
temperature matching the expected behavior from asymptotic freedom. The thermal
gluon condensate is calculated and shown to be crucial for the existence of a
non-trivial deconfining transition. The condensate of the topological charge is
shown to vanish in the deconfined phase.Comment: LaTeX, 61 pages (main body) + 58 pages (appendix), 25 eps figures.
Revised version, published in JHEP. Two equations added in Section 7.4; typos
corrected; references adde
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