491 research outputs found
Challenges of D=6 N=(1,1) SYM Theory
Maximally supersymmetric Yang-Mills theories have several remarkable
properties, among which are the cancellation of UV divergences, factorization
of higher loop corrections and possible integrability. Much attention has been
attracted to the N=4 D=4 SYM theory. The N=(1,1) D=6 SYM theory possesses
similar properties but is nonrenomalizable and serves as a toy model for
supergravity. We consider the on-shell four point scattering amplitude and
analyze its perturbative expansion within the spin-helicity and superspace
formalism. The integrands of the resulting diagrams coincide with those of the
N=4 D=4 SYM and obey the dual conformal invariance. Contrary to 4 dimensions,
no IR divergences on mass shell appear. We calculate analytically the leading
logarithmic asymptotics in all loops. Their summation leads to a Regge
trajectory which is calculated exactly. The leading powers of s are calculated
up to six loops. Their summation is performed numerically and leads to a smooth
function of s. The leading UV divergences are calculated up to 5 loops. The
result suggests the geometrical progression which ends up in a finite
expression. This leads us to a radical point of view on nonrenormalizable
theories.Comment: 11 pages, 2 figures, Late
Divergences in maximal supersymmetric Yang-Mills theories in diverse dimensions
The main aim of this paper is to study the scattering amplitudes in gauge
field theories with maximal supersymmetry in dimensions D=6,8 and 10. We
perform a systematic study of the leading ultraviolet divergences using the
spinor helicity and on-shell momentum superspace framework. In D=6 the first
divergences start at 3 loops and we calculate them up to 5 loops, in D=8,10 the
first divergences start at 1 loop and we calculate them up to 4 loops. The
leading divergences in a given order are the polynomials of Mandelstam
variables. To be on the safe side, we check our analytical calculations by
numerical ones applying the alpha-representation and the dedicated routines.
Then we derive an analog of the RG equations for the leading pole that allows
us to get the recursive relations and construct the generating procedure to
obtain the polynomials at any order of (perturbation theory) PT. At last, we
make an attempt to sum the PT series and derive the differential equation for
the infinite sum. This equation possesses a fixed point which might be stable
or unstable depending on the kinematics. Some consequences of these fixed
points are discussed.Comment: 43 pages, 13 figures, pdf LaTex, v2 minor changes and references
adde
Политическая стабильность и нестабильность как элемент политической системы древневосточных государств (на примере Древнего Египта).
Власенко Д.И.Политическая стабильность и нестабильность как элемент политической системы древневосточных государств (на примере Древнего Египта). / Д.И.Власенко // Актуальні проблеми політики : зб. наук. пр. / редкол. : С. В. Ківалов (голов. ред.), Л. І. Кормич (заст. голов. ред.), Ю. П. Аленін [та ін.] ; МОНмолодьспорт України, НУ ОЮА. – Одеса : Фенікс, 2011. – Вип. 12-18 . С.294 - 305.In the work the questions connected with all aspects of a stable and unstable
condition of political system of Ancient Egypt are considered. The expediency
of studying of political system of Ancient Egypt proves, classifi cation of vari-
ous conditions of political stability-instability is offered
Horizontal dispersion in shelf seas: High resolution modelling as an aid to sparse sampling
The ability of a hydrodynamic model to reproduce the results of a dye release experiment conducted in a wide shelf sea environment was investigated with the help of the Massachusetts Institute of Technology general circulation model (MITgcm). In the field experiment a fluorescent tracer, Rhodamine WT, was injected into the seasonal pycnocline, and its evolution was tracked for two days using a towed undulating vehicle equipped with a fluorometer and a CTD. With a 50. m horizontal resolution grid, and with three different forcings initialized in the model (viz: tides, stationary current, and wind stress on the free surface), it was possible to replicate the dye patch evolution quite accurately. The mechanisms responsible for the enhancement of horizontal dispersion were investigated on the basis of the model results. It was found that enhancement of the dye dispersion was controlled by vertically sheared currents that, in combination with vertical diapycnal mixing, led to a substantial increase in the "effective" horizontal mixing. The values of "effective" horizontal mixing found from the model runs were in good agreement with those obtained from in-situ data, and the probable degree to which the observational techniques undersampled the dye patch was revealed
- …