5,374 research outputs found
Infrared finitness and analyticity properties of the loop-loop scattering amplitudes in gauge theories
We shall discuss about the infrared finitness and some analyticity properties
of the loop-loop scattering amplitudes in gauge theories, when going from
Minkowskian to Euclidean theory, and we shall see how they can be related to
the still unsolved problem of the s-dependence of the hadron-hadron total
cross-sections.Comment: Talk given at the ``International Workshop on Diffraction in
High-Energy Physics'' (DIFFRACTION 2004), Cala Gonone (Sardinia, Italy),
18-23 September 2004; 3 pages, LaTeX fil
Direct solution of the hard pomeron problem for arbitrary conformal weight
A new method is applied to solve the Baxter equation for the one dimensional
system of noncompact spins. Dynamics of such an ensemble is equivalent to that
of a set of reggeized gluons exchanged in the high energy limit of QCD
amplitudes. The technique offers more insight into the old calculation of the
intercept of hard Pomeron, and provides new results in the odderon channel.Comment: Contribution to the ICHEP96 Conference, July 1996, Warsaw, Poland.
LaTeX, 4 pages, 3 epsf figures, includes modified stwol.sty file. Some
references were revise
The AdS_5xS^5 superstring worldsheet S-matrix and crossing symmetry
An S-matrix satisying the Yang-Baxter equation with symmetries relevant to
the AdS_5xS^5 superstring has recently been determined up to an unknown scalar
factor. Such scalar factors are typically fixed using crossing relations,
however due to the lack of conventional relativistic invariance, in this case
its determination remained an open problem.
In this paper we propose an algebraic way to implement crossing relations for
the AdS_5xS^5 superstring worldsheet S-matrix. We base our construction on a
Hopf-algebraic formulation of crossing in terms of the antipode and introduce
generalized rapidities living on the universal cover of the parameter space
which is constructed through an auxillary, coupling constant dependent,
elliptic curve. We determine the crossing transformation and write functional
equations for the scalar factor of the S-matrix in the generalized rapidity
plane.Comment: 27 pages, no figures; v2: sign typo fixed in (24), everything else
unchange
Solution of the Odderon Problem
The intercept of the odderon trajectory is derived, by finding the spectrum
of the second integral of motion of the three reggeon system in high energy
QCD. When combined with earlier solution of the appropriate Baxter equation,
this leads to the determination of the low lying states of that system. In
particular, the energy of the lowest state gives the intercept of the odderon
alpha_O(0)=1-0.2472 alpha_s N_c/pi.Comment: 11 pages, 2 Postscript figure
A hybrid approach to space power control
Conventional control systems have traditionally been utilized for space-based power designs. However, the use of expert systems is becoming important for NASA applications. Rocketdyne has been pursuing the development of expert systems to aid and enhance control designs of space-based power systems. The need for integrated expert systems is vital for the development of autonomous power systems
Flavors in an expanding plasma
We consider the effect of an expanding plasma on probe matter by determining
time-dependent D7 embeddings in the holographic dual of an expanding viscous
plasma. We calculate the chiral condensate and meson spectra including
contributions of viscosity. The chiral condensate essentially confirms the
expectation from the static black hole. For the meson spectra we propose a
scheme that is in agreement with the adiabatic approximation. New contributions
arise for the vector mesons at the order of the viscosity terms.Comment: 15 pages, 7 figures; v2: accepted for publ. in Phys. Rev. D; revised
mass definition agrees with adiabatic approximatio
Supergravitons from one loop perturbative N=4 SYM
We determine the partition function of 1/16 BPS operators in N=4 SYM at weak
coupling at the one-loop level in the planar limit. This partition function is
significantly different from the one computed at zero coupling. We find that it
coincides precisely with the partition function of a gas of 1/16 BPS
`supergravitons' in AdS_5xS^5.Comment: 22 pages; v2: references adde
Viscous hydrodynamics relaxation time from AdS/CFT
We consider an expanding boost-invariant plasma at strong coupling using the
AdS/CFT correspondence for N=4 SYM. We determine the relaxation time in second
order viscous hydrodynamics and find that it is around thirty times shorter
than weak coupling expectations. We find that the nonsingularity of the dual
geometry in the string frame necessitates turning on the dilaton which leads to
a nonvanishing expectation value for tr F^2 behaving like tau^(-10/3).Comment: 10 pages, Mathematica script included in the source; v2: typo in (28)
fixed, statement about electric/magnetic modes correcte
Asymptotic perfect fluid dynamics as a consequence of AdS/CFT
We study the dynamics of strongly interacting gauge-theory matter (modelling
quark-gluon plasma) in a boost-invariant setting using the AdS/CFT
correspondence. Using Fefferman-Graham coordinates and with the help of
holographic renormalization, we show that perfect fluid hydrodynamics emerges
at large times as the unique nonsingular asymptotic solution of the nonlinear
Einstein equations in the bulk. The gravity dual can be interpreted as a black
hole moving off in the fifth dimension. Asymptotic solutions different from
perfect fluid behaviour can be ruled out by the appearance of curvature
singularities in the dual bulk geometry. Subasymptotic deviations from perfect
fluid behaviour remain possible within the same framework.Comment: 19 pages, 1 figure; v2: free streaming example changed to s=1;
conclusions unchange
Dynamical tachyons on fuzzy spheres
We study the spectrum of off-diagonal fluctuations between displaced fuzzy
spheres in the BMN plane wave matrix model. The displacement is along the plane
of the fuzzy spheres. We find that when two fuzzy spheres intersect at angles
classical tachyons develop and that the spectrum of these modes can be computed
analytically. These tachyons can be related to the familiar Nielsen-Olesen
instabilities in Yang-Mills theory on a constant magnetic background. Many
features of the problem become more apparent when we compare with maximally
supersymmetric Yang-Mills on a sphere, of which this system is a truncation. We
also set up a simple oscillatory trajectory on the displacement between the
fuzzy spheres and study the dynamics of the modes as they become tachyonic for
part of the oscillations. We speculate on their role regarding the possible
thermalization of the system.Comment: 34 pages, 4 figures; v2: 35 pages, expanded sec. 4.3, added
reference
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