Search results for "Variant"
showing 10 items of 1267 documents
Nearly-integrable dissipative systems and celestial mechanics
2010
The influence of dissipative effects on classical dynamical models of Celestial Mechanics is of basic importance. We introduce the reader to the subject, giving classical examples found in the literature, like the standard map, the Hénon map, the logistic mapping. In the framework of the dissipative standard map, we investigate the existence of periodic orbits as a function of the parameters. We also provide some techniques to compute the breakdown threshold of quasi-periodic attractors. Next, we review a simple model of Celestial Mechanics, known as the spin-orbit problem which is closely linked to the dissipative standard map. In this context we present the conservative and dissipative KA…
Comparison of woods-saxon and double-folding potentials forα-particle scattering from54Fe at 24.5 MeV
1988
Inelastic-scattering data are presented forα-particles of 24.5 MeV from54Fe over the range 15° to 175° in the centre-of-mass system. The real part of the optical potential is calculated microscopically using the M3Y effective interaction of Bertschet al. and the DDM3Y density-dependent interaction. Elastic scattering has been analysed by using as real part of the optical potential M3Y, DDM3Y and Woods-Saxon forms (WS), taking in all three cases as imaginary part a WS potential. To fit the data the double-folding potential needs to be normalized by a factor of ⋍1.6 for the M3Y interaction and of ⋍1.13 for the DDM3Y interaction. By the study of the invariant-point ambiguity it has been observ…
Study of the DKK and DKK¯ systems
2017
Using the fixed center approximation to Faddeev equations, we investigate the $DKK$ and $DK\overline{K}$ three-body systems, considering that the $DK$ dynamically generates, through its $I=0$ component, the ${D}_{s0}^{*}(2317)$ molecule. According to our findings, for the $DK\overline{K}$ interaction we find evidence of a state $I({J}^{P})=1/2({0}^{\ensuremath{-}})$ just above the ${D}_{s0}^{*}(2317)\overline{K}$ threshold and around the $D{f}_{0}(980)$ threshold, with mass of about 2833--2858 MeV, made mostly of $D{f}_{0}(980)$. On the other hand, no evidence related to a state from the $DKK$ interaction is found. The state found could be seen in the $\ensuremath{\pi}\ensuremath{\pi}D$ inv…
A three body state with J=3 in the ρB*B̅N* interaction
2016
We study the ρB * BN * system solving the Faddeev equations in the fixed center approximation. The B * BN * system will be considered forming a cluster, and using the two-body ρB * unitarized scattering amplitudes in the local Hidden Gauge approach we find a new I ( J PC ) = 1(3 −− ) state. The mass of the new state corresponds to a two particle invariant mass of the ρB * system close to the resonant energy of the B * 2 (5747), indicating that the role of this J = 2 resonance is important in the dynamical generation of the new state.
Aligned Electric and Magnetic Weyl Fields
2003
We analyze the spacetimes admitting a direction for which the relative electric and magnetic Weyl fields are aligned. We give an invariant characterization of these metrics and study the properties of its Debever null vectors. The directions 'observing' aligned electric and magnetic Weyl fields are obtained for every Petrov type. The results on the no existence of purely magnetic solutions are extended to the wider class having homothetic electric and magnetic Weyl fields.
A covariant determination of the Weyl canonical frames in Petrov type I spacetimes
1997
A covariant algorithm is given to obtain principal 2-forms, Debever null directions and canonical frames associated with Petrov type I Weyl tensors. The relationship between these Weyl elements is explained, and their explicit expressions depending on Weyl invariants are obtained. These results are used to determine a cosmological observer in type I universes, and their usefulness in spacetime intrinsic characterization is shown.
Backlund transformations in 2-D dilaton gravity
1998
We give a B\"acklund transformation connecting a generic 2D dilaton gravity theory to a generally covariant free field theory. This transformation provides an explicit canonical transformation relating both theories.
Schwinger mechanism in linear covariant gauges
2016
In this work we explore the applicability of a special gluon mass generating mechanism in the context of the linear covariant gauges. In particular, the implementation of the Schwinger mechanism in pure Yang-Mills theories hinges crucially on the inclusion of massless bound-state excitations in the fundamental nonperturbative vertices of the theory. The dynamical formation of such excitations is controlled by a homogeneous linear Bethe-Salpeter equation, whose nontrivial solutions have been studied only in the Landau gauge. Here, the form of this integral equation is derived for general values of the gauge-fixing parameter, under a number of simplifying assumptions that reduce the degree of…
Generalized curvature and the equations of D=11 supergravity
2005
It is known that, for zero fermionic sector, the bosonic equations of Cremmer-Julia-Scherk eleven-dimensional supergravity can be collected in a compact expression which is a condition on the curvature of the generalized connection. Here we peresent the equation which collects all the bosonic equations of D=11 supergravity when the gravitino is nonvanishing.
Local BRST cohomology in gauge theories
2000
The general solution of the anomaly consistency condition (Wess-Zumino equation) has been found recently for Yang-Mills gauge theory. The general form of the counterterms arising in the renormalization of gauge invariant operators (Kluberg-Stern and Zuber conjecture) and in gauge theories of the Yang-Mills type with non power counting renormalizable couplings has also been worked out in any number of spacetime dimensions. This Physics Report is devoted to reviewing in a self-contained manner these results and their proofs. This involves computing cohomology groups of the differential introduced by Becchi, Rouet, Stora and Tyutin, with the sources of the BRST variations of the fields ("antif…