979,189 research outputs found
Renormalization Group Flow in Scalar-Tensor Theories. II
We study the UV behaviour of actions including integer powers of scalar
curvature and even powers of scalar fields with Functional Renormalization
Group techniques. We find UV fixed points where the gravitational couplings
have non-trivial values while the matter ones are Gaussian. We prove several
properties of the linearized flow at such a fixed point in arbitrary dimensions
in the one-loop approximation and find recursive relations among the critical
exponents. We illustrate these results in explicit calculations in for
actions including up to four powers of scalar curvature and two powers of the
scalar field. In this setting we notice that the same recursive properties
among the critical exponents, which were proven at one-loop order, still hold,
in such a way that the UV critical surface is found to be five dimensional. We
then search for the same type of fixed point in a scalar theory with minimal
coupling to gravity in including up to eight powers of scalar curvature.
Assuming that the recursive properties of the critical exponents still hold,
one would conclude that the UV critical surface of these theories is five
dimensional.Comment: 14 pages. v.2: Minor changes, some references adde
The economics of defence in France and the UK
France and the UK face similar geostrategic circumstances: both were once Great Powers and still retain their positions among the five permanent members of the UN Security Council. During the Cold War both were dwarfed by the super-powers and were thus extremely sensitive about their status: what the French called their grandeur and the British called their seat at the top table. Despite their strategic similarities, they have differed in many of their defence policy choices and in particular how they balanced their strategic aspirations with their limited financial resources. Thus a comparison of British and French defence policies provides a revealing case study of military choices
Reconstruction of the primordial fluctuation spectrum from the five-year WMAP data by the cosmic inversion method with band-power decorrelation analysis
The primordial curvature fluctuation spectrum is reconstructed by the cosmic
inversion method using the five-year WMAP data of the cosmic microwave
background temperature anisotropy. We apply the covariance matrix analysis and
decompose the reconstructed spectrum into statistically independent
band-powers. The statistically significant deviation from a simple power-law
spectrum suggested by the analysis of the first-year data is not found in the
five-year data except possibly at one point near the border of the wavenumber
domain where accurate reconstruction is possible.Comment: 9page
Laurent series expansion of sunrise-type diagrams using configuration space techniques
We show that configuration space techniques can be used to efficiently
calculate the complete Laurent series \eps-expansion of sunrise-type diagrams
to any loop order in D-dimensional space-time for any external momentum and for
arbitrary mass configurations. For negative powers of \eps the results are
obtained in analytical form. For positive powers of \eps including the finite
\eps^0 contribution the result is obtained numerically in terms of
low-dimensional integrals. We present general features of the calculation and
provide exemplary results up to five loop order which are compared to available
results in the literature.Comment: 20 pages, 3 eps-figures include
Open Spinning Strings
We find classical open string solutions in the AdS_5\times S^5/\Zop_2
orientifold with angular momenta along the five-sphere. The energy of these
solutions has an expansion in integral powers of with sigma-model
corrections suppressed by inverse powers of - the total angular momentum.
This gives a prediction for the exact anomalous dimensions of operators in the
large limit of an Super-Yang-Mills theory with matter.
We also find a simple map between open and closed string solutions. This gives
a prediction for an all-loop planar relationship between the anomalous
dimensions of single-trace and two-quark operators in the dual gauge theory
Primary electric power generation systems for advanced-technology engines
The advantages of the all electric airplane are discussed. In the all electric airplane the generator is the sole source of electric power; it powers the primary and secondary flight controls, the environmentals, and the landing gear. Five candidates for all electric power systems are discussed and compared. Cost benefits of the all electric airplane are discussed
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